Sky at Night - April 2014

the biggest name in astronomy

solar system hotspot

New insights into the volcanic moon Io

preserving the night

The UK’s newest Dark Sky areas uncovered

aPriL 2014 #107www.skyatnightmagazine.com

see mars at its brightest and best

Discover why this once wet world is now a desert

the worLD’s

biggest & best

night-sky guiDe

Sky at Night

life in low

earth orbitThe challenges of living and working on the ISS

scope test

light unlocked

steady on

The new instruments that will reveal the secrets of starlight

Expert techniques to hold binoculars higher for longer

also in

this issue

Meade’s new LX600 telescope with automatic guiding built in

planet

return oF thered

create a stunning moon mosaic image

the biggest name in astronomy

solar system hotspot

New insights into the volcanic moon Io

preserving the night

The UK’s newest Dark Sky areas uncovered

aPriL 2014 #107www.skyatnightmagazine.com

see mars at its brightest and best

Discover why this once wet world is now a desert

the worLD’s

biggest & best

night-sky guiDe

Sky at Night

life in low

earth orbitThe challenges of living and working on the ISS

scope test

light unlocked

steady on

The new instruments that will reveal the secrets of starlight

Expert techniques to hold binoculars higher for longer

also in

this issue

Meade’s new LX600 telescope with automatic guiding built in

planet

return oF thered

create a stunning moon mosaic image

TECHNOLOGICALLYSUPERIOR

Celestron’s innovative new SkyQ Link WiFi Module turns your iPhone or iPad into your own personal planetarium and observatory!

Automatically align your Celestron telescope with our StarSense Accessory!The revolutionary technology in the award-winning SkyProdigy telescope is now available for almost every Celestron computerised telescope.

Celestron®, SkyQTM and StarSenseTM are trademarks or registered trademarks of Celestron Acquisition, LLC in the United States and in dozens of other countries around the world.

All rights reserved. David Hinds Ltd is an authorised distributor and reseller of Celestron products. The iPhone® and iPad® are trademarks of Apple Inc., registered in the U.S. and other countries.

AppStore is a trademark of Apple Inc.

www.celestron.uk.comImagine the possibilities

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TECHNOLOGICALLYSUPERIOR

Celestron’s innovative new SkyQ Link WiFi Module turns your iPhone or iPad into your own personal planetarium and observatory!

Automatically align your Celestron telescope with our StarSense Accessory!The revolutionary technology in the award-winning SkyProdigy telescope is now available for almost every Celestron computerised telescope.

Celestron®, SkyQTM and StarSenseTM are trademarks or registered trademarks of Celestron Acquisition, LLC in the United States and in dozens of other countries around the world.

All rights reserved. David Hinds Ltd is an authorised distributor and reseller of Celestron products. The iPhone® and iPad® are trademarks of Apple Inc., registered in the U.S. and other countries.

AppStore is a trademark of Apple Inc.

www.celestron.uk.comImagine the possibilities

StarSenseAccessory

F1 Telescopes

Sittingbourne

01795 432702

Green Witch (North)

West Yorkshire

01924 477719

Astronomia

Dorking

01306 640714

Green Witch (South)

Bedfordshire

01767 677025

Widescreen Centre

Central London

020 7935 2580

SkyQ LinkWiFi Module

Align and control your Celestron telescope wirelessly using your iPhone or iPad!

and specialist dealers nationwide

Special Offer! Big Savings now available on

all NexStar SE telescopes.Contact your local Celestron Dealer

for more information.

Letter from the editor APRIL 03

skyatnightmagazine.com 2014

Welcome

HoW to contact usSubscriptions, binders, CD cases and back issues0844 844 0254 Mon to Fri 8am to 8pm; Sat 9am to 1pm for ordersEditorial enquiries0117 314 7411 9.30am to 5.30pm, Mon to Fri Advertising enquiries0117 314 8365

Subscription email enquiries [email protected] [email protected] enquirieshttp://apps.immediate.co.uk/support [email protected]

Editorial enquiries BBC Sky at Night Magazine, Immediate Media Co Bristol Ltd, Tower House, Fairfax Street, Bristol, BS1 3BN

stepHen tonkin

Binocular oBserver

Stephen dispenses his top tips on how to get steadier

views when observing with binoculars in this month’s How to. Page 90

Will Gater

astronomy author

Will marks the invention of the spectroscope with a look

at how its modern-day equivalents continue to aid astronomers. Page 73

Martin leWis

Planetary imager

Martin explains how to make the most of the

Red Planet its brightest and best for the current apparition. Page 41

sean Blair

sPace writer

Sean tackles a planetary murder mystery:

what happened to the atmosphere of the Red Planet? 4

ps Next issue goes on sale 17 April.

this month’s contributors include...

Chris Bramley editor

Everything you need to know about Mars’s opposition

sky at night lots of ways to enjoy the night sky...

poDcast

The BBC Sky at Night Magazine team discuss the latest astro news in our monthly podcast

tWitter

Follow @skyatnightmag to keep up with the latest space stories and tell us what you think

online Visit our website for reviews, competitions, astrophotos, observing guides and our forum

television Find out what The Sky at Night team will be exploring in this month’s episode on page 19

ipaD

Get each month’s issue on your iPad, now with bonus video and extra images

FaceBook

All the details of our latest issue, plus news from the magazine and updates to our website

how to capture the images, then process and stitch them together to create a fnal masterpiece rich in detail. And on page 73, there’s the fascinating tale of one of astronomy’s most unsung tools – the spectroscope. To tie in with the 200th anniversary of its invention, we look at how this instrument continues to unlock the secrets of starlight.

Enjoy the issue!

From Mariner 4’s frst visit in 1964 to Curiosity’s present-day explorations, Mars is the most visited destination for space probes. Now two new spacecraft are on their way to the Red Planet to uncover

more about its atmosphere. The data NASA’s MAVEN and India’s Mars Orbiter Mission will send back is set to give us new insights into the planet’s protective envelope, why it disappeared and the impact this had on the planet’s potentially life-sustaining supply of water. Find out more on page 34.

Though Mars’s dust storms and carbon dioxide ice are visible with a telescope, its tenuous atmosphere is one thing you won’t see, even with the planet at its brightest this month. April’s opposition is a great time to see the raft of details visible on the planet. From the dark markings that break up Mars’s red-hued globe to the white polar caps, Martin Lewis’s feature on page 41 shows you how to get the most out of observing and imaging the Red Planet this apparition. You’ll also fnd expert advice on imaging Mars on page 64, and on page 93, Carol Lakomiak explains how to sketch the planet.

Elsewhere this month, on page 80 you’ll fnd a detailed guide to creating a lunar mosaic. Pete Lawrence takes you through

Letter from the editor APRIL 03


Welcome

HoW to contact usSubscriptions, binders, CD cases and back issues0844 844 0254 Mon to Fri 8am to 8pm; Sat 9am to 1pm for ordersEditorial enquiries0117 314 7411 9.30am to 5.30pm, Mon to Fri Advertising enquiries0117 314 8365

Subscription email enquiries [email protected] [email protected] enquirieshttp://apps.immediate.co.uk/support [email protected]

Editorial enquiries BBC Sky at Night Magazine, Immediate Media Co Bristol Ltd, Tower House, Fairfax Street, Bristol, BS1 3BN

stepHen tonkin

Binocular oBserver

Stephen dispenses his top tips on how to get steadier

views when observing with binoculars in this month’s How to. Page 90

Will Gater

astronomy author

Will marks the invention of the spectroscope with a look

at how its modern-day equivalents continue to aid astronomers. Page 73

Martin leWis

Planetary imager

Martin explains how to make the most of the

Red Planet its brightest and best for the current apparition. Page 41

sean Blair

sPace writer

Sean tackles a planetary murder mystery:

what happened to the atmosphere of the Red Planet? Page 34

ps Next issue goes on sale 17 April.

this month’s contributors include...

Chris Bramley editor

Everything you need to know about Mars’s opposition

sky at night lots of ways to enjoy the night sky...

poDcast

The BBC Sky at Night Magazine team discuss the latest astro news in our monthly podcast

tWitter

Follow @skyatnightmag to keep up with the latest space stories and tell us what you think

online Visit our website for reviews, competitions, astrophotos, observing guides and our forum

television Find out what The Sky at Night team will be exploring in this month’s episode on page 19

ipaD

Get each month’s issue on your iPad, now with bonus video and extra images

FaceBook

All the details of our latest issue, plus news from the magazine and updates to our website

how to capture the images, then process and stitch them together to create a fnal masterpiece rich in detail. And on page 73, there’s the fascinating tale of one of astronomy’s most unsung tools – the spectroscope. To tie in with the 200th anniversary of its invention, we look at how this instrument continues to unlock the secrets of starlight.

Enjoy the issue!

From Mariner 4’s frst visit in 1964 to Curiosity’s present-day explorations, Mars is the most visited destination for space probes. Now two new spacecraft are on their way to the Red Planet to uncover

more about its atmosphere. The data NASA’s MAVEN and India’s Mars Orbiter Mission will send back is set to give us new insights into the planet’s protective envelope, why it disappeared and the impact this had on the planet’s potentially life-sustaining supply of water. Find out more on page 34.

Though Mars’s dust storms and carbon dioxide ice are visible with a telescope, its tenuous atmosphere is one thing you won’t see, even with the planet at its brightest this month. April’s opposition is a great time to see the raft of details visible on the planet. From the dark markings that break up Mars’s red-hued globe to the white polar caps, Martin Lewis’s feature on page 41 shows you how to get the most out of observing and imaging the Red Planet this apparition. You’ll also fnd expert advice on imaging Mars on page 64, and on page 93, Carol Lakomiak explains how to sketch the planet.

Elsewhere this month, on page 80 you’ll fnd a detailed guide to creating a lunar mosaic. Pete Lawrence takes you through

04


mosaicing the moon80

mars at opposition41

First Light102

80

On the cOver

features

34

90

16

66

98

regulars

Inthemagazine New to astroNomy?See The guide on page 88 and our online glossary

at www.skyatnightmagazine.com/dictionary

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06Eye on the skyStunning new images of space.

34 Mars’s missing atmosphere

The greatest whodunnit of them all: we explore

the mystery of the disappearing atmosphere.

41 Mars at oppositionThe ultimate guide to viewing and imaging

the Red Planet as it comes to opposition.

66 Dark skies recognisedHow two more UK sites gained Dark Sky status.

73 Unlocking the secrets of light

How the humble spectroscope will lead the James

Webb Space Telescope into a new era of astronomy.

80 Mosaicing the MoonAll you need to know to create your frst lunar

mosaic, from image acquisition to completion.

73

88Skills88The guide The Local Group of galaxies.

90How to Get steadier binocular views.

93Sketching Mars at opposition.

95Scope Doctor

97ReviewsFirst Light

98 Meade LX600-ACF

12-inch Schmidt-Cassegrain.

102 William Optics GTF 102

fve-element astrograph.

Tried & Tested106QSI 683 WSG-8 CCD camera.

110Books 112Gear

114What I really want to know is…What is life like on the ISS?

11Bulletin

19What’s on

21A passion for spaceSky at Night presenter Maggie

Aderin-Pocock tells us what

we can learn from the sounds of space.

23Jon CulshawJon’s off-world travelogue continues.

24sUBscriBe get your issues at a discount

26Interactive

28Hotshots

51the sky iN

aPriL Your 15-page guide to the

night sky featuring the top

sights, an all-sky chart, a

deep-sky tour and more…

114

51

NEW

04


mosaicing the moon80

mars at opposition41

First Light102

80

On the cOver

features

34

90

16

66

98

regulars

Inthemagazine New to astroNomy?See The guide on page 88 and our online glossary

at www.skyatnightmagazine.com/dictionary

co

ver

: th

ink

sto

ck

. n

asa

, th

is p

ag

e: d

am

ian

pea

ch

, pe

te l

aw

ren

ce,

ww

w.t

hes

ecre

tstu

dio

.net

06Eye on the skyStunning new images of space.

34 Mars’s missing atmosphere

The greatest whodunnit of them all: we explore

the mystery of the disappearing atmosphere.

41 Mars at oppositionThe ultimate guide to viewing and imaging

the Red Planet as it comes to opposition.

66 Dark skies recognisedHow two more UK sites gained Dark Sky status.

73 Unlocking the secrets of light

How the humble spectroscope will lead the James

Webb Space Telescope into a new era of astronomy.

80 Mosaicing the MoonAll you need to know to create your frst lunar

mosaic, from image acquisition to completion.

73

88Skills88The guide The Local Group of galaxies.

90How to Get steadier binocular views.

93Sketching Mars at opposition.

95Scope Doctor

97ReviewsFirst Light

98 Meade LX600-ACF

12-inch Schmidt-Cassegrain.

102 William Optics GTF 102

fve-element astrograph.

Tried & Tested106QSI 683 WSG-8 CCD camera.

110Books 112Gear

114What I really want to know is…What is life like on the ISS?

11Bulletin

19What’s on

21A passion for spaceSky at Night presenter Maggie

Aderin-Pocock tells us what

we can learn from the sounds of space.

23Jon CulshawJon’s off-world travelogue continues.

24sUBscriBe get your issues at a discount

26Interactive

28Hotshots

51the sky iN

aPriL Your 15-page guide to the

night sky featuring the top

sights, an all-sky chart, a

deep-sky tour and more…

114

51

NEW

skyatnightmagazine.com 2012 skyatnightmagazine.com 2012

aVaiLaBLe noW on itUnes – onLy £3.99 to download visit www.skyatnightmagazine.com/man-in-space-ipad-app

the Man In Space app is more than a digital book – it’s a complete multimedia experience. tap the screen to play videos, rotate spacecraft views and bring interactive

elements into play. you’ll never feel closer to being in space.

MAN IN SPACE iPAD APPcelebrate 50 years of mankind’s adventure in space

this app features: 3D views of legendary spacecraft, allowing you to examine them from different angles themed photo galleries featuring amazing images historic video footage interactive diagrams 360º panoramic views of the moon a foreword by sir patrick moore

skyatnightmagazine.com 2012 skyatnightmagazine.com 2012

aVaiLaBLe noW on itUnes – onLy £3.99 to download visit www.skyatnightmagazine.com/man-in-space-ipad-app

the Man In Space app is more than a digital book – it’s a complete multimedia experience. tap the screen to play videos, rotate spacecraft views and bring interactive

elements into play. you’ll never feel closer to being in space.

MAN IN SPACE iPAD APPcelebrate 50 years of mankind’s adventure in space

this app features: 3D views of legendary spacecraft, allowing you to examine them from different angles themed photo galleries featuring amazing images historic video footage interactive diagrams 360º panoramic views of the moon a foreword by sir patrick moore

There are more than 100 asteroids visible in this image from NASA’s Wide-feld Infrared Survey Explorer (WISE). Although it is not easy to spot them all, some do stand out as a series of dots – like asteroid (2415) Ganesa, which can be seen just left of centre.

The asteroids, located within our Solar System, sit against an infrared view of a background star feld around 30 lightyears across. Along with bright clusters, like NGC

2158 to the centre right, this star feld is home to vast, billowing clouds of gas and dust revealed in infrared light. The data used to create this image was captured during WISE’s primary all-sky survey. The spacecraft went into hibernation shortly afterwards in 2011 but was revived last year, renamed NEOWISE and commissioned to hunt down more of the elusive space rocks captured so brilliantly in this image.

WIdE-fIEld INfrArEd SurvEy ExplOrEr, 23 JANuAry 2014

Against gas clouds and star clusters, an armada of space rocks sails silently through the darkness

amassAsteroids

There are more than 100 asteroids visible in this image from NASA’s Wide-feld Infrared Survey Explorer (WISE). Although it is not easy to spot them all, some do stand out as a series of dots – like asteroid (2415) Ganesa, which can be seen just left of centre.

The asteroids, located within our Solar System, sit against an infrared view of a background star feld around 30 lightyears across. Along with bright clusters, like NGC

2158 to the centre right, this star feld is home to vast, billowing clouds of gas and dust revealed in infrared light. The data used to create this image was captured during WISE’s primary all-sky survey. The spacecraft went into hibernation shortly afterwards in 2011 but was revived last year, renamed NEOWISE and commissioned to hunt down more of the elusive space rocks captured so brilliantly in this image.

WIdE-fIEld INfrArEd SurvEy ExplOrEr, 23 JANuAry 2014

Against gas clouds and star clusters, an armada of space rocks sails silently through the darkness

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▲ A grand spiral in the southern sky

HubblE SpACE TElESCOpE 9 JANuAry 2014

This image of M83, the Southern pinwheel galaxy, shows off a beautiful range of vivid hues. The reason for such vibrancy: a vast number of stars in the throngs of birth and death. M83 is a barred spiral, the same type of galaxy as the Milky Way, but unlike our home in space it has a ‘double nucleus’ at its heart.

Engaging rings

CASSINI SpACECrAfT 20 JANuAry 2014

Saturn’s famous ring system takes centre stage in this infrared image from Cassini. Taken from a distance of 1.1 million km, it reveals a bright spot in the rings – look for it just left of centre – called an opposition surge. This occurs when the Sun is directly behind the probe. Astronomers will analyse the size and magnitude of the surge to learn more about the properties of the ring particles.


▲ A grand spiral in the southern sky

HubblE SpACE TElESCOpE 9 JANuAry 2014

This image of M83, the Southern pinwheel galaxy, shows off a beautiful range of vivid hues. The reason for such vibrancy: a vast number of stars in the throngs of birth and death. M83 is a barred spiral, the same type of galaxy as the Milky Way, but unlike our home in space it has a ‘double nucleus’ at its heart.

Engaging rings

CASSINI SpACECrAfT 20 JANuAry 2014

Saturn’s famous ring system takes centre stage in this infrared image from Cassini. Taken from a distance of 1.1 million km, it reveals a bright spot in the rings – look for it just left of centre – called an opposition surge. This occurs when the Sun is directly behind the probe. Astronomers will analyse the size and magnitude of the surge to learn more about the properties of the ring particles.

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eye on the sky APRIL 09


Rose tinted gasses

EurOpEAN SOuTHErN ObSErvATOry, 22 JANuAry 2014

ESO’s very large Telescope captured the lagoon Nebula in exquisite, pale pink detail in this stunning new image. The nebula, a vast stellar factory where new stars are born, spans almost 100 lightyears in diameter, and lies between 4,000 and 6,000 lightyears from Earth.

The leftover lake

MArS ExprESS SpACECrAfT, 12 dECEMbEr 2013

Giant mounds of layered deposits sit surrounded by soft sand and dust in Mars’s Juventae Chasma. New observations like the one from ESA’s Mars Express indicate that running water may have been responsible for moulding these mounds – scientists believe the numerous layers were mainly built up from lake deposits.

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eye on the sky APRIL 09


Rose tinted gasses

EurOpEAN SOuTHErN ObSErvATOry, 22 JANuAry 2014

ESO’s very large Telescope captured the lagoon Nebula in exquisite, pale pink detail in this stunning new image. The nebula, a vast stellar factory where new stars are born, spans almost 100 lightyears in diameter, and lies between 4,000 and 6,000 lightyears from Earth.

The leftover lake

MArS ExprESS SpACECrAfT, 12 dECEMbEr 2013

Giant mounds of layered deposits sit surrounded by soft sand and dust in Mars’s Juventae Chasma. New observations like the one from ESA’s Mars Express indicate that running water may have been responsible for moulding these mounds – scientists believe the numerous layers were mainly built up from lake deposits.

THE ASPEN SERIES IS OUR NEWEST AND

MOST ADVANCED CCD CAMERA EVER.

Image of Ghost Nebula (vdB 141) shot using our new Aspen CG16m CCD camera

©2013 Apogee Imaging Systems Inc. Aspen is a trademark of Apogee Imaging Systems, Inc.

Aspen delivers industry-leading performance with both its cooling (up to -70 degrees C) and its shutter with

reliability rated at 5 million cycles. All this is achieved within a smaller form factor. Aspen also delivers improved

stray light baffling to minimize internal reflections and its back-focus requirements have been reduced to

accommodate more OTAs and accessories. Aspen Series cameras come standard with 2 interfaces, USB 2

and an Ethernet interface with a built-in web server. Read out rates up to 16Mhz are supported. All our cameras

are backed by a full 2-year warranty on the camera and lifetime warranty on the CCD chamber integrity.

Our new Aspen Series delivers quality and reliability so you can focus on innovation and discovery.

THE ASPEN SERIES IS OUR NEWEST AND

MOST ADVANCED CCD CAMERA EVER.

Image of Ghost Nebula (vdB 141) shot using our new Aspen CG16m CCD camera

©2013 Apogee Imaging Systems Inc. Aspen is a trademark of Apogee Imaging Systems, Inc.

Aspen delivers industry-leading performance with both its cooling (up to -70 degrees C) and its shutter with

reliability rated at 5 million cycles. All this is achieved within a smaller form factor. Aspen also delivers improved

stray light baffling to minimize internal reflections and its back-focus requirements have been reduced to

accommodate more OTAs and accessories. Aspen Series cameras come standard with 2 interfaces, USB 2

and an Ethernet interface with a built-in web server. Read out rates up to 16Mhz are supported. All our cameras

are backed by a full 2-year warranty on the camera and lifetime warranty on the CCD chamber integrity.

Our new Aspen Series delivers quality and reliability so you can focus on innovation and discovery.

Comment by Chris LintottThe key to understanding this bizarre new system is that it orbits not one, but two stars – one of a handful of ‘circumbinary’ planets known.

Since the discovery of the frst such world, a hardy group of theorists and computer modellers have been trying to fgure out the rules that dictate how such planets might form. Their results suggested that the gravitational pull of the binary star would wrench any protoplanetary disc and hence any subsequent planets into alignment.

That process clearly wasn’t effective here, leaving Kepler-413b on an orbit that only sometimes produces transits. Its inclination is only a couple of degrees – not unprecedented, but enough in this case to make a big difference to what we see. With planets around binary stars already proving much more common than anyone would have suspected a few years ago, this window onto what we might be missing is hugely signifcant.

ChrIS LInToTT co-presents The Sky at Night

The latest astronomy and space news written by Hazel Muir

Our experts examine the hottest new astronomy research papers

CUttInG

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Circumbinary planets are rare, with only a handful found so far

Bulletin APRIL 11


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14 CHris LintOtt 16 Lewis DartneLL

Wobbly planet circles

double starNASA ScieNtiStS hAve discovered a strange

world that wobbles wildly on its axis, much like

a child’s spinning top. its tilt may change by as

much as 30º over 11 years, resulting in extreme

and rapid climate changes.

the planet, a gas giant known as Kepler-413b,

is about 65 times as massive as earth and sits in

the constellation of cygnus. it orbits a close pair

of dwarf stars every 66 days, causing them to

dim slightly as it passes in front. this should

happen like clockwork but – as the Kepler space

telescope revealed – the gas giant’s transits are

unusually irregular.

“Looking at the Kepler data over the course of

1,500 days, we saw three transits in the first 180

days, then we had 800 days with no transits at all,”

says team leader veselin Kostov from the Space

telescope Science institute (StSci) in Maryland.

“After that, we saw five more transits in a row.”

the planet’s orbit is tilted by 2.5º in relation

to the orbit of the binary stellar pair; these

observations suggest that the planet’s orbit

wobbles too, so much that the planet often

fails to pass in front of the stars from our

perspective on earth.

intriguingly, the finding may also mean that

many transiting planets may go undetected

because their transits are rare. “Presumably

there are planets out there like this one that

we’re not seeing because we’re in the

unfavourable period,” says Peter Mccullough,

also from StSci. “is there a silent majority

that we’re not seeing?”

> See Comment, right

Is this the frst member of a ‘silent majority’ of unseen planets?

Comment by Chris LintottThe key to understanding this bizarre new system is that it orbits not one, but two stars – one of a handful of ‘circumbinary’ planets known.

Since the discovery of the frst such world, a hardy group of theorists and computer modellers have been trying to fgure out the rules that dictate how such planets might form. Their results suggested that the gravitational pull of the binary star would wrench any protoplanetary disc and hence any subsequent planets into alignment.

That process clearly wasn’t effective here, leaving Kepler-413b on an orbit that only sometimes produces transits. Its inclination is only a couple of degrees – not unprecedented, but enough in this case to make a big difference to what we see. With planets around binary stars already proving much more common than anyone would have suspected a few years ago, this window onto what we might be missing is hugely signifcant.

ChrIS LInToTT co-presents The Sky at Night

The latest astronomy and space news written by Hazel Muir

Our experts examine the hottest new astronomy research papers

CUttInG

eDGe

plUs

Circumbinary planets are rare, with only a handful found so far

Bulletin APRIL 11


Bulletin N

ASA

/JPL

-CA

LteC

h

14 CHris LintOtt 16 Lewis DartneLL

Wobbly planet circles

double starNASA ScieNtiStS hAve discovered a strange

world that wobbles wildly on its axis, much like

a child’s spinning top. its tilt may change by as

much as 30º over 11 years, resulting in extreme

and rapid climate changes.

the planet, a gas giant known as Kepler-413b,

is about 65 times as massive as earth and sits in

the constellation of cygnus. it orbits a close pair

of dwarf stars every 66 days, causing them to

dim slightly as it passes in front. this should

happen like clockwork but – as the Kepler space

telescope revealed – the gas giant’s transits are

unusually irregular.

“Looking at the Kepler data over the course of

1,500 days, we saw three transits in the first 180

days, then we had 800 days with no transits at all,”

says team leader veselin Kostov from the Space

telescope Science institute (StSci) in Maryland.

“After that, we saw five more transits in a row.”

the planet’s orbit is tilted by 2.5º in relation

to the orbit of the binary stellar pair; these

observations suggest that the planet’s orbit

wobbles too, so much that the planet often

fails to pass in front of the stars from our

perspective on earth.

intriguingly, the finding may also mean that

many transiting planets may go undetected

because their transits are rare. “Presumably

there are planets out there like this one that

we’re not seeing because we’re in the

unfavourable period,” says Peter Mccullough,

also from StSci. “is there a silent majority

that we’re not seeing?”

> See Comment, right

Is this the frst member of a ‘silent majority’ of unseen planets?

12


Newly discovered gas streams may explain vigorous star formation

An intriguing river of hydrogen fowing

through space has been spotted by a radio

telescope in West virginia. Astronomers say

such flaments, never seen before because they

are so faint, could explain how some spiral

galaxies manage to maintain constant, vigorous

star formation.

Spiral galaxies like our own Milky Way

typically have rather tranquil, but steady,

star formation. But the star formation in some

others is more lively. these galaxies often

have warm shrouds of hydrogen gas, but

astronomers suspected they must also have

cold hydrogen infows to explain the high

star-formation rates.

“We knew that the fuel for star formation had

to come from somewhere,” says Daniel Pisano

from West virginia university in Morgantown.

“So far, however, we’ve detected only about 10

per cent of what would be necessary to explain

what we observe in many galaxies.”

One leading theory is that rivers of gas,

known as cold fows, ferry hydrogen through

intergalactic space, with large galaxies

Odyssey gets a new quest NASA is gradually altering the orbit of its Mars Odyssey spacecraft to allow the probe to view the planet’s surface in morning daylight. It will reach its intended new orbit in November 2015 and make the frst systematic observations of how morning fogs, clouds and surface frost develop.

Its measurements could help demystify temperature- driven processes, such as fows forming on slopes during warm seasons.

“We’re teaching an old spacecraft new tricks,” says Jeffrey Plaut from NASA’s Jet Propulsion Laboratory in California. “Odyssey will be in position to see Mars in a different light than ever before.”

effectively siphoning cold gas away from

their smaller neighbours. the cold gas then

becomes fuel for new stars. “But this tenuous

hydrogen has been simply too diffuse to

detect, until now,” says Pisano.

He has discovered one of the hypothesised

rivers of hydrogen after studying a galaxy called

ngC 6946. this galaxy lies about 22 million

lightyears away on the border of the Cepheus

and Cygnus. Observations using the 100m green

Bank telescope revealed the faint glow of a

neutral hydrogen stream connecting ngC 6946

with neighbouring galaxies, suggesting it does

indeed siphon hydrogen off its smaller neighbours.

An alternative possibility is that the cold

hydrogen stream exists because ngC 6946 had

a close encounter with another galaxy in the

distant past. this interaction could have left a

ribbon of neutral atomic hydrogen in its wake.

if that were the case, however, astronomers

would expect to see a small but observable

population of stars in the flament, which

have not been detected.

www.gb.nrao.edu

NA

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news in

brief

Rivers of hydrogen fuel galaxies

ngC 6946 and its companions appear to be linked by a trail of diffuse hydrogen, shown in red

extreme blaCk hOle disCOveredA black hole in an elliptical galaxy about 3.9 billion lightyears away may be the most powerful ever found.

Julie Hlavacek-Larrondo from Stanford University in California and colleagues made the discovery using NASA’s Chandra X-ray Observatory and other telescopes. They estimate that the black hole is about a thousand trillion times as massive as the Sun. Energetic jets sprouting out from it seem to have created two large cavities, each as wide as our Milky Way, severely curtailing star formation.

12


Newly discovered gas streams may explain vigorous star formation

An intriguing river of hydrogen fowing

through space has been spotted by a radio

telescope in West virginia. Astronomers say

such flaments, never seen before because they

are so faint, could explain how some spiral

galaxies manage to maintain constant, vigorous

star formation.

Spiral galaxies like our own Milky Way

typically have rather tranquil, but steady,

star formation. But the star formation in some

others is more lively. these galaxies often

have warm shrouds of hydrogen gas, but

astronomers suspected they must also have

cold hydrogen infows to explain the high

star-formation rates.

“We knew that the fuel for star formation had

to come from somewhere,” says Daniel Pisano

from West virginia university in Morgantown.

“So far, however, we’ve detected only about 10

per cent of what would be necessary to explain

what we observe in many galaxies.”

One leading theory is that rivers of gas,

known as cold fows, ferry hydrogen through

intergalactic space, with large galaxies

Odyssey gets a new quest NASA is gradually altering the orbit of its Mars Odyssey spacecraft to allow the probe to view the planet’s surface in morning daylight. It will reach its intended new orbit in November 2015 and make the frst systematic observations of how morning fogs, clouds and surface frost develop.

Its measurements could help demystify temperature- driven processes, such as fows forming on slopes during warm seasons.

“We’re teaching an old spacecraft new tricks,” says Jeffrey Plaut from NASA’s Jet Propulsion Laboratory in California. “Odyssey will be in position to see Mars in a different light than ever before.”

effectively siphoning cold gas away from

their smaller neighbours. the cold gas then

becomes fuel for new stars. “But this tenuous

hydrogen has been simply too diffuse to

detect, until now,” says Pisano.

He has discovered one of the hypothesised

rivers of hydrogen after studying a galaxy called

ngC 6946. this galaxy lies about 22 million

lightyears away on the border of the Cepheus

and Cygnus. Observations using the 100m green

Bank telescope revealed the faint glow of a

neutral hydrogen stream connecting ngC 6946

with neighbouring galaxies, suggesting it does

indeed siphon hydrogen off its smaller neighbours.

An alternative possibility is that the cold

hydrogen stream exists because ngC 6946 had

a close encounter with another galaxy in the

distant past. this interaction could have left a

ribbon of neutral atomic hydrogen in its wake.

if that were the case, however, astronomers

would expect to see a small but observable

population of stars in the flament, which

have not been detected.

www.gb.nrao.edu

NA

SA

/JPL

, D

.J.

PiSA

No

(W

VU

) B.

SA

xto

N (

NR

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PA

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AN

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Ste

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news in

brief

Rivers of hydrogen fuel galaxies

ngC 6946 and its companions appear to be linked by a trail of diffuse hydrogen, shown in red

extreme blaCk hOle disCOveredA black hole in an elliptical galaxy about 3.9 billion lightyears away may be the most powerful ever found.

Julie Hlavacek-Larrondo from Stanford University in California and colleagues made the discovery using NASA’s Chandra X-ray Observatory and other telescopes. They estimate that the black hole is about a thousand trillion times as massive as the Sun. Energetic jets sprouting out from it seem to have created two large cavities, each as wide as our Milky Way, severely curtailing star formation.

Bulletin APRIL 13


gALACTIC fAMILy TrEES NO LONgEr A MySTEryRigoRous obseRvations by world-leading

telescopes, including Hubble and Herschel, have

unravelled the history of the most massive galaxies

in the universe. the results show how early galaxies

evolved via initial violent bursts of star formation

into extremely high-density galaxy cores, then

fnally collided to form giant elliptical galaxies.

the timeline solves a decade-long mystery

about how compact elliptical galaxies that existed

when the universe was only three billion years old

– less than a quarter of its current age – but had

already completed most of their star formation.

Asteroid’s odd interior revealed

asteRoids can Have a highly varied internal

structure, scientists say. observations of peanut-

shaped near-earth asteroid 25143 itokawa suggest

that its density is more than 60 per cent higher on

one side than it is on the other. it’s the frst time

that such a difference has been found.

stephen Lowry from the university of Kent

and colleagues studied the space rock – visited by

the Japanese spacecraft Hayabusa in 2005 – using

a telescope at the La silla observatory in chile.

their measurements of its spin rate combined

with theoretical models hint that itokawa has two

distinct densities. one possibility for this could

be that it formed from two rocks that merged.

“this is the frst time we have ever been able to

determine what it is like inside an asteroid,” says

Lowry, who calls it “a signifcant step” forward.

www.eso.org/lasilla

nasa and FranCe plan mars prObeThe US has teamed up with france to launch a lander to Mars in 2016. Space offcials from both nations have signed an agreement to join forces on the InSight mission, which will measure seismic activity on Mars and reveal structural details of its deep interior.

“The research generated by this collaborative mission will give our agencies more information about the early formation of Mars, which will help us understand more about how Earth evolved,” says NASA administrator Charles Bolden.

saturn’s aurOrae in Full glOryUsing images from Hubble and NASA’s Cassini spacecraft from April and May 2013, astronomers have compiled a movie of aurorae at Saturn’s poles. It should clarify how the giant planet’s polar light shows evolve following solar outbursts.

“In 2013, we were treated to a veritable smorgasbord of dancing aurorae, from steadily shining rings to super-fast bursts of light shooting across the pole,” says Jonathan Nichols from the University of Leicester, who led the work on the Hubble images.

news in

brief The density of a space rock can be extremely variable

the two parts of asteroid itokawa have markedly different densities

the study directly shows they’re descendants of

an earlier population of dusty ‘starburst’ galaxies

that voraciously used up available gas for star

formation very quickly.

“We at last show how these compact galaxies can

form, how it happened and when it happened,” says

sune toft from the niels bohr institute in copenhagen,

denmark, whose team confrmed the evolutionary

tree through detailed studies of many galaxies of

different ages. after the compact phase, the galaxies

grew slowly through mergers into giant ellipticals.

www.hubblesite.org

2,850kg/m3

1,750kg/m3

the evolution of giant ellipticals has been laid bare

tOday

13.7 billion years 5 billion years3 billion years

2 billion years1.5 billion years

1 billion years

local elliptical galaxymerging galaxies

Compact galaxy

quasardusty starburst

galaxy

merger

big bang

Bulletin APRIL 13


gALACTIC fAMILy TrEES NO LONgEr A MySTEryRigoRous obseRvations by world-leading

telescopes, including Hubble and Herschel, have

unravelled the history of the most massive galaxies

in the universe. the results show how early galaxies

evolved via initial violent bursts of star formation

into extremely high-density galaxy cores, then

fnally collided to form giant elliptical galaxies.

the timeline solves a decade-long mystery

about how compact elliptical galaxies that existed

when the universe was only three billion years old

– less than a quarter of its current age – but had

already completed most of their star formation.

Asteroid’s odd interior revealed

asteRoids can Have a highly varied internal

structure, scientists say. observations of peanut-

shaped near-earth asteroid 25143 itokawa suggest

that its density is more than 60 per cent higher on

one side than it is on the other. it’s the frst time

that such a difference has been found.

stephen Lowry from the university of Kent

and colleagues studied the space rock – visited by

the Japanese spacecraft Hayabusa in 2005 – using

a telescope at the La silla observatory in chile.

their measurements of its spin rate combined

with theoretical models hint that itokawa has two

distinct densities. one possibility for this could

be that it formed from two rocks that merged.

“this is the frst time we have ever been able to

determine what it is like inside an asteroid,” says

Lowry, who calls it “a signifcant step” forward.

www.eso.org/lasilla

nasa and FranCe plan mars prObeThe US has teamed up with france to launch a lander to Mars in 2016. Space offcials from both nations have signed an agreement to join forces on the InSight mission, which will measure seismic activity on Mars and reveal structural details of its deep interior.

“The research generated by this collaborative mission will give our agencies more information about the early formation of Mars, which will help us understand more about how Earth evolved,” says NASA administrator Charles Bolden.

saturn’s aurOrae in Full glOryUsing images from Hubble and NASA’s Cassini spacecraft from April and May 2013, astronomers have compiled a movie of aurorae at Saturn’s poles. It should clarify how the giant planet’s polar light shows evolve following solar outbursts.

“In 2013, we were treated to a veritable smorgasbord of dancing aurorae, from steadily shining rings to super-fast bursts of light shooting across the pole,” says Jonathan Nichols from the University of Leicester, who led the work on the Hubble images.

news in

brief The density of a space rock can be extremely variable

the two parts of asteroid itokawa have markedly different densities

the study directly shows they’re descendants of

an earlier population of dusty ‘starburst’ galaxies

that voraciously used up available gas for star

formation very quickly.

“We at last show how these compact galaxies can

form, how it happened and when it happened,” says

sune toft from the niels bohr institute in copenhagen,

denmark, whose team confrmed the evolutionary

tree through detailed studies of many galaxies of

different ages. after the compact phase, the galaxies

grew slowly through mergers into giant ellipticals.

www.hubblesite.org

2,850kg/m3

1,750kg/m3

the evolution of giant ellipticals has been laid bare

tOday

13.7 billion years 5 billion years3 billion years

2 billion years1.5 billion years

1 billion years

local elliptical galaxymerging galaxies

Compact galaxy

quasardusty starburst

galaxy

merger

big bang

NA

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14

Most of the buzz surrounding the recent

supernova 2014J in relatively local

M82 is due to its status as the nearest

Type Ia event in more than a century.

We normally hear about Type Ia supernovae when

they’re used to measure the expansion of the

Universe and the effects of ‘dark energy’, but all of

this cosmological excitement hides the embarrassing

truth that these supernovae are poorly understood.

The standard picture of a Type Ia supernova

depends on the transfer of material between two

stars, locked in a mutual gravitational embrace in a

binary system. If one of the stars is a white dwarf,

and the two are close enough, then material will be

pulled off the larger star and build up on the

smaller one. Once enough material has accreted,

then thermonuclear ignition becomes inevitable,

and we see a supernova.

This seems right – the need for a set amount of

material to trigger ignition explains why Type Ia

supernovae have roughly the same luminosity

wherever they occur, with some adjustment for

factors such as the composition of the material. But

not all Type Ia supernovae ft this pattern. Suggestions

include exotic models of stellar evolution, interactions

between two white dwarfs or even mergers in triple

star systems. Whatever is going on, a growing body

of evidence suggests an important role is played by

so-called ‘prompt’ Type Ia supernovae, which occur

less than 500 million years into a system’s lifetime.

A new Hubble Space Telescope survey of 24 Type

Ia supernovae sets out to understand how the

distribution of prompt and standard supernovae

has changed over cosmic time. Given that this

survey looks more than 10 billion years into the

past, to a time when star formation was much more

prevalent than it is today, we should expect the

number of progenitors capable of producing either

prompt or standard supernovae to be different from

that in the local Universe. Previous surveys had

suggested that such analysis would reveal that the

prompt variant might account for as many as half

of all Type Ia supernovae. Given the rising star-

formation rate as we look back in time, that should

mean plenty of supernovae for us to observe.

In fact, few supernovae were found in the most

distant galaxies included in the survey, which

suggests that prompt supernovae accounting for

half of all such events might be an overestimation.

The data favour a much lower fraction, perhaps as

small as one in 20, albeit with small error bars.

Far from understanding what prompt Type Ia

supernovae are, we’re still struggling to count them.

More observations will help, and large Hubble surveys

are already underway. Given M82’s status as a

prolifc star-forming system, though, and the

chance that 2014J is a prompt event, perhaps the

best way to study these objects is to look closer to

home, fun though staring at the distant Universe is.

Chris Lintott is an astrophysicist and co-presenter of The Sky at Night on BBC TV. He is also the director of the Zooniverse project.

Chris Lintott was reading… Type Ia Supernova Rate Measurements to Redshift 2.5 from CANDELS: Searching for Prompt Explosions in the Early Universe by Steven A Rodney et alread it online at http://arxiv.org/abs/1401.7978

our experts examine the hottest new research

the type ia supernova designated 2014J exploded in M82, 11.5 million lightyears from Earth. it was the closest supernova of this type discovered in the past few decades

The prompt supernovaeType Ia supernovae appear to be more varied then we originally thought

CUTTING

EDGE

“A growing body of evidence suggests an important role is played by prompt Type Ia supernovae”

NA

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14

Most of the buzz surrounding the recent

supernova 2014J in relatively local

M82 is due to its status as the nearest

Type Ia event in more than a century.

We normally hear about Type Ia supernovae when

they’re used to measure the expansion of the

Universe and the effects of ‘dark energy’, but all of

this cosmological excitement hides the embarrassing

truth that these supernovae are poorly understood.

The standard picture of a Type Ia supernova

depends on the transfer of material between two

stars, locked in a mutual gravitational embrace in a

binary system. If one of the stars is a white dwarf,

and the two are close enough, then material will be

pulled off the larger star and build up on the

smaller one. Once enough material has accreted,

then thermonuclear ignition becomes inevitable,

and we see a supernova.

This seems right – the need for a set amount of

material to trigger ignition explains why Type Ia

supernovae have roughly the same luminosity

wherever they occur, with some adjustment for

factors such as the composition of the material. But

not all Type Ia supernovae ft this pattern. Suggestions

include exotic models of stellar evolution, interactions

between two white dwarfs or even mergers in triple

star systems. Whatever is going on, a growing body

of evidence suggests an important role is played by

so-called ‘prompt’ Type Ia supernovae, which occur

less than 500 million years into a system’s lifetime.

A new Hubble Space Telescope survey of 24 Type

Ia supernovae sets out to understand how the

distribution of prompt and standard supernovae

has changed over cosmic time. Given that this

survey looks more than 10 billion years into the

past, to a time when star formation was much more

prevalent than it is today, we should expect the

number of progenitors capable of producing either

prompt or standard supernovae to be different from

that in the local Universe. Previous surveys had

suggested that such analysis would reveal that the

prompt variant might account for as many as half

of all Type Ia supernovae. Given the rising star-

formation rate as we look back in time, that should

mean plenty of supernovae for us to observe.

In fact, few supernovae were found in the most

distant galaxies included in the survey, which

suggests that prompt supernovae accounting for

half of all such events might be an overestimation.

The data favour a much lower fraction, perhaps as

small as one in 20, albeit with small error bars.

Far from understanding what prompt Type Ia

supernovae are, we’re still struggling to count them.

More observations will help, and large Hubble surveys

are already underway. Given M82’s status as a

prolifc star-forming system, though, and the

chance that 2014J is a prompt event, perhaps the

best way to study these objects is to look closer to

home, fun though staring at the distant Universe is.

Chris Lintott is an astrophysicist and co-presenter of The Sky at Night on BBC TV. He is also the director of the Zooniverse project.

Chris Lintott was reading… Type Ia Supernova Rate Measurements to Redshift 2.5 from CANDELS: Searching for Prompt Explosions in the Early Universe by Steven A Rodney et alread it online at http://arxiv.org/abs/1401.7978

our experts examine the hottest new research

the type ia supernova designated 2014J exploded in M82, 11.5 million lightyears from Earth. it was the closest supernova of this type discovered in the past few decades

The prompt supernovaeType Ia supernovae appear to be more varied then we originally thought

CUTTING

EDGE

“A growing body of evidence suggests an important role is played by prompt Type Ia supernovae”

As pulsars spin, their

radiation beams sweep

across the cosmos


April 1983On 10 April 1983, The Sky at Night broadcast discussed a bizarre new sighting in the night sky. Astronomers had discovered a pulsar, known as PSR B1937+21, spinning 642 times a second.

A pulsar is a neutron star, which forms when a massive star explodes in a supernova, leaving behind a superdense core roughly 15km wide. Neutron stars can emit intense radiation from their magnetic poles, and if their radiation beams sweep

Mars gains a fresh crater

GAiA OPeNS itS eyeS

Spacecraft images reveal a spectacular new impact

ESA’S GAiA SpAcEcrAft has taken a stunning

test image following its launch in December 2013.

the shot, shown right, shows a dense cluster of

stars within the Large Magellanic cloud, a

satellite galaxy of the Milky Way.

“it provides just a tiny taste of the excellence

and challenges ahead, to turn Gaia data into

human understanding of the Milky Way’s

origins,” says Gaia scientist Gerry Gilmore from

the University of cambridge. “One substantial

step for astronomy, one huge leap still to come.”

Gaia will observe a billion stars around

70 times every year in an attempt to build our

most accurate map of the Milky Way.

http://sci.esa.int/gaia

NASA’S MArS rEcONNAiSSANcE Orbiter has

spotted a dramatic new crater on the red planet.

the impact scar, which is around 30km wide,

did not exist in images dating back to July 2010,

but turned up in shots taken in May 2012. After

noticing the change, scientists used the orbiter’s

HiriSE camera to take a closer look at the

region in November 2013 – capturing the image

shown on the left.

it’s been estimated that more than 200 of the

space rocks that hit Mars every year create craters at

least 3.9m wide, but few of the impacts look as striking

as this one, which is surrounded a radial burst of

debris that few out over a distance of about 15km.

NASA launched the Mars reconnaissance Orbiter

in August 2005. it entered Mars’s orbit in March 2006.

www.nasa.gov/mroThe new crater is not really blue; this tint is a result of enhanced colourisation to remove reddish dust

Looking back

Bulletin APRIL 15

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We’re unlikely to see many images like this from Gaia – its main role is that of a galactic cartographer

across earth as they rotate, we can observe regular pulses from them.

the discovery of PSR B1937+21 was extraordinary – how could a pulsar possibly spin that fast? Astronomers concluded that they can be spun up to enormous speeds when companion stars dump material onto them, delivering angular momentum. the spin rate of PSR B1937+21 has since been surpassed by only one other known pulsar, spinning 716 times a second.

BroWn dWArf hAs red skiesUsing the Very Large telescope in Chile, astronomers have found a nearby brown dwarf star with curiously red skies.

Brown dwarfs are stars that are too small to ignite hydrogen fusion in their cores but too large to be considered planets. One brown dwarf that lies at least 100 lightyears away caught the attention of Federico Marocco from the University of Hertfordshire and his colleagues due to its unusually red atmosphere.

“the thick clouds on this particular brown dwarf are mostly made of mineral dust,” says Marocco. the compounds include the magnesium-rich mineral enstatite and a crystalline form of aluminium oxide.

news in

brief

Mercury iMAGes MounT upNASA’s Messenger spacecraft, launched in 2004, has now returned more than 200,000 images of the planet Mercury – 200 times the number promised in the mission proposal. the probe will now have its orbit lowered so it can take high-resolution images of the rocky world’s surface.

As pulsars spin, their

radiation beams sweep

across the cosmos


April 1983On 10 April 1983, The Sky at Night broadcast discussed a bizarre new sighting in the night sky. Astronomers had discovered a pulsar, known as PSR B1937+21, spinning 642 times a second.

A pulsar is a neutron star, which forms when a massive star explodes in a supernova, leaving behind a superdense core roughly 15km wide. Neutron stars can emit intense radiation from their magnetic poles, and if their radiation beams sweep

Mars gains a fresh crater

GAiA OPeNS itS eyeS

Spacecraft images reveal a spectacular new impact

ESA’S GAiA SpAcEcrAft has taken a stunning

test image following its launch in December 2013.

the shot, shown right, shows a dense cluster of

stars within the Large Magellanic cloud, a

satellite galaxy of the Milky Way.

“it provides just a tiny taste of the excellence

and challenges ahead, to turn Gaia data into

human understanding of the Milky Way’s

origins,” says Gaia scientist Gerry Gilmore from

the University of cambridge. “One substantial

step for astronomy, one huge leap still to come.”

Gaia will observe a billion stars around

70 times every year in an attempt to build our

most accurate map of the Milky Way.

http://sci.esa.int/gaia

NASA’S MArS rEcONNAiSSANcE Orbiter has

spotted a dramatic new crater on the red planet.

the impact scar, which is around 30km wide,

did not exist in images dating back to July 2010,

but turned up in shots taken in May 2012. After

noticing the change, scientists used the orbiter’s

HiriSE camera to take a closer look at the

region in November 2013 – capturing the image

shown on the left.

it’s been estimated that more than 200 of the

space rocks that hit Mars every year create craters at

least 3.9m wide, but few of the impacts look as striking

as this one, which is surrounded a radial burst of

debris that few out over a distance of about 15km.

NASA launched the Mars reconnaissance Orbiter

in August 2005. it entered Mars’s orbit in March 2006.

www.nasa.gov/mroThe new crater is not really blue; this tint is a result of enhanced colourisation to remove reddish dust

Looking back

Bulletin APRIL 15

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We’re unlikely to see many images like this from Gaia – its main role is that of a galactic cartographer

across earth as they rotate, we can observe regular pulses from them.

the discovery of PSR B1937+21 was extraordinary – how could a pulsar possibly spin that fast? Astronomers concluded that they can be spun up to enormous speeds when companion stars dump material onto them, delivering angular momentum. the spin rate of PSR B1937+21 has since been surpassed by only one other known pulsar, spinning 716 times a second.

BroWn dWArf hAs red skiesUsing the Very Large telescope in Chile, astronomers have found a nearby brown dwarf star with curiously red skies.

Brown dwarfs are stars that are too small to ignite hydrogen fusion in their cores but too large to be considered planets. One brown dwarf that lies at least 100 lightyears away caught the attention of Federico Marocco from the University of Hertfordshire and his colleagues due to its unusually red atmosphere.

“the thick clouds on this particular brown dwarf are mostly made of mineral dust,” says Marocco. the compounds include the magnesium-rich mineral enstatite and a crystalline form of aluminium oxide.

news in

brief

Mercury iMAGes MounT upNASA’s Messenger spacecraft, launched in 2004, has now returned more than 200,000 images of the planet Mercury – 200 times the number promised in the mission proposal. the probe will now have its orbit lowered so it can take high-resolution images of the rocky world’s surface.

NA

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16

Io is the most volcanically active body in

the Solar System. It’s a fractious and violent

little world, and fascinating to study as its

face is constantly changing. We learned a

lot about Io from the Galileo probe’s tour of the

Jovian system between 1996 and 2001, and got

a feeting glimpse most recently when the New

Horizons probe swung past Jupiter on its journey

towards Pluto.

For a few days around 28 February 2007, New

Horizons was able to train its cameras on Io. It took

200 photos of Jupiter’s moon during this fyby and

Dr Julie Rathbun of the Planetary Science Institute

in Tuscon and colleagues have written a paper

about what they show. Many of the photos were

taken when Jupiter was eclipsing Io, casting a

shadow over the moon’s surface – perfect for

hunting for glowing volcanic areas.

Most of the volcanoes observed by the Galileo

probe were still active when New Horizons few

past, six years later. One of them, Pele, is among

Io’s most enduring hotspots – it was glowing when

it was frst detected by Voyager in 1979 and Rathbun

found that it was still going strong in 2007. New

Horizons was able to photograph several volcanoes

repeatedly and found no variability in their

brightness – they’re very stable in their intensity.

By far the brightest hotspot seen by New

Horizons was a volcano called Tvashtar. It was such

an intense thermal source that it didn’t just show up

in images taken using an infrared flter, but also those

taken in the red band. This was important because it

allowed Rathbun to work out Tvashtar’s temperature.

The hotter an object is, the shorter the

wavelength of light it emits. The human body glows

in the far-infrared at about 10μm; a red-hot poker

emits light at wavelengths a few microns long; light

emitted by the Sun peaks at about 0.5μm, shining

brilliantly at visible and ultraviolet wavelengths. By

comparing the brightness of Tvashtar at both

infrared and red wavelengths, Rathbun was able to

calculate the hotspot’s temperature to be about

950°C, which is the same as lava fows on Earth.

Curiously, East Girru, the second-brightest

thermal source seen on Io by New Horizons wasn’t

seen by Voyager in 1979, or Galileo in the late 1990s,

or indeed from any ground-based telescopes. East

Girru lies 200km from a hotspot that was seen by

Galileo, and so Rathbun has concluded that it’s a

new eruption. But, when comparing the highest-

resolution photos from Galileo and New Horizons

of the landscape around East Girru, she couldn’t

see any noticeable changes between the two, nor

any lighter region of the type that’s normally seen

around volcanic sites on Io. So this new intense

hotspot is something of a mystery: what’s the

source of all that activity?

Lewis DartneLL is an astrobiology research fellow at the University of Leicester. His new book The Knowledge will be published in April.

Lewis DartneLL was reading… Io’s active volcanoes during the New Horizons era: Insights from New Horizons imaging by J A rathbun et al. read it online at http://dx.doi.org/10.1016/ j.icarus.2013.12.002

Our experts examine the hottest new research

io seen through three new Horizons instruments; the tvashtar volcano near the moon’s north pole is the brightest hotspot in each image, with a temperature of 950°C

The violence of IoImages taken by the New Horizons probe are giving us a greater insight into this highly volcanic moon

CUTTING

EDGE

“Pele was glowing when it was frst detected by Voyager in 1979 and was still going strong in 2007”

NA

SA/J

oh

NS

ho

pkiN

S U

Niv

erSi

ty A

ppli

ed p

hyS

icS

lAbo

rA

tory

/So

Uth

weS

t re

SeA

rch

iNSt

itU

te


16

Io is the most volcanically active body in

the Solar System. It’s a fractious and violent

little world, and fascinating to study as its

face is constantly changing. We learned a

lot about Io from the Galileo probe’s tour of the

Jovian system between 1996 and 2001, and got

a feeting glimpse most recently when the New

Horizons probe swung past Jupiter on its journey

towards Pluto.

For a few days around 28 February 2007, New

Horizons was able to train its cameras on Io. It took

200 photos of Jupiter’s moon during this fyby and

Dr Julie Rathbun of the Planetary Science Institute

in Tuscon and colleagues have written a paper

about what they show. Many of the photos were

taken when Jupiter was eclipsing Io, casting a

shadow over the moon’s surface – perfect for

hunting for glowing volcanic areas.

Most of the volcanoes observed by the Galileo

probe were still active when New Horizons few

past, six years later. One of them, Pele, is among

Io’s most enduring hotspots – it was glowing when

it was frst detected by Voyager in 1979 and Rathbun

found that it was still going strong in 2007. New

Horizons was able to photograph several volcanoes

repeatedly and found no variability in their

brightness – they’re very stable in their intensity.

By far the brightest hotspot seen by New

Horizons was a volcano called Tvashtar. It was such

an intense thermal source that it didn’t just show up

in images taken using an infrared flter, but also those

taken in the red band. This was important because it

allowed Rathbun to work out Tvashtar’s temperature.

The hotter an object is, the shorter the

wavelength of light it emits. The human body glows

in the far-infrared at about 10μm; a red-hot poker

emits light at wavelengths a few microns long; light

emitted by the Sun peaks at about 0.5μm, shining

brilliantly at visible and ultraviolet wavelengths. By

comparing the brightness of Tvashtar at both

infrared and red wavelengths, Rathbun was able to

calculate the hotspot’s temperature to be about

950°C, which is the same as lava fows on Earth.

Curiously, East Girru, the second-brightest

thermal source seen on Io by New Horizons wasn’t

seen by Voyager in 1979, or Galileo in the late 1990s,

or indeed from any ground-based telescopes. East

Girru lies 200km from a hotspot that was seen by

Galileo, and so Rathbun has concluded that it’s a

new eruption. But, when comparing the highest-

resolution photos from Galileo and New Horizons

of the landscape around East Girru, she couldn’t

see any noticeable changes between the two, nor

any lighter region of the type that’s normally seen

around volcanic sites on Io. So this new intense

hotspot is something of a mystery: what’s the

source of all that activity?

Lewis DartneLL is an astrobiology research fellow at the University of Leicester. His new book The Knowledge will be published in April.

Lewis DartneLL was reading… Io’s active volcanoes during the New Horizons era: Insights from New Horizons imaging by J A rathbun et al. read it online at http://dx.doi.org/10.1016/ j.icarus.2013.12.002

Our experts examine the hottest new research

io seen through three new Horizons instruments; the tvashtar volcano near the moon’s north pole is the brightest hotspot in each image, with a temperature of 950°C

The violence of IoImages taken by the New Horizons probe are giving us a greater insight into this highly volcanic moon

CUTTING

EDGE

“Pele was glowing when it was frst detected by Voyager in 1979 and was still going strong in 2007”

Bulletin APRIL 17


Heavy isotope titanium-44, imaged by NuSTAR and shown in blue, is clearly clustered at the centre of the explosion

What makes stars explode?NASA’s NuSTAR may have uncovered why stars become violently unstable

The mysTery of how stars explode might fnally

be solved. X-ray observations taken by NAsA’s

Nuclear spectroscopic Telescope Array (NusTAr)

suggest material in soon-to-explode stars sloshes

around violently, energising a shock wave

that blows the star to smithereens.

NusTAr was launched into

low-earth orbit in June

2012. Now it has created

the frst map of

radioactive material

in a supernova

remnant,

Cassiopeia A,

which lies

about 11,000

lightyears

from us.

Cassiopeia A

formed when

a massive star

exploded after

running out of

fuel; the light of this

detonation reached

earth roughly 300 years

ago. During the blast, high

temperatures made lighter

elements fuse into heavier ones,

and now NusTAr has created a

map of one of the heavy isotopes

in Cassiopeia A, titanium-44.

The map resolves some puzzles about

supernovae. During the explosion, a shock wave

somehow blasts the star apart, yet previous

computer simulations of this process failed to

replicate this. Instead they suggested that the

NA

SA

/JPL

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main shock wave would stall, preventing the star

from shattering. NusTAr revealed that titanium

is concentrated in clumps at Cassiopeia A’s centre.

Astronomers conclude from this that material in

the former star sloshed around, re-energising

the shock wave that fnally made it

blast off its outer layers.

“stars are spherical

balls of gas, so you

might think that

when they end their

lives and explode,

that explosion

would look like

a uniform ball

expanding

out,” says

NusTAr

scientist fiona

harrison from

the California

Institute of

Technology. “our

new results show

how the explosion’s

engine is distorted,

possibly because the inner

regions literally slosh around

before detonating.”

The NusTAr map also casts

doubt on another model of

supernovae, in which a star

rotates rapidly enough to launch energetic jets

of gas that drive the explosion. Although there’s

evidence of jets in Cassiopeia A, NusTAr’s

observations suggest they did not trigger the blast.

www.nasa.gov/nustar

JoiN THe HuNT foR plANeTARy SySTemSNASA is asking for help in fnding embryonic planetary systems in observations from the Wide-feld Infrared Survey Explorer (WISE) spacecraft. There may be thousands lurking in the data, but they can only be found through human inspection, which poses a huge challenge.

“Volunteers will help the astronomical community discover new planetary nurseries that will become future targets for NASA’s Hubble Space Telescope and its successor, the James Webb Space Telescope,” says James Garvin from NASA’s Goddard Space Flight Center in Maryland.www.diskdetective.org

news in

brief

AT lAST: A GlobAl mAp of GANymedeMore than four centuries after its discovery, the Solar System’s largest moon – Jupiter’s Ganymede – fnally has a global map. Wes Patterson from the Johns Hopkins University in Maryland and colleagues compiled it using images from NASA’s Voyager and Galileo missions.

HoW STARS CARVE STRANGE NEbUlAELow-mAss sTArs like the sun can end their

lives as double-lobed planetary nebulae if they

have close companions, a new study suggests.

sun-like stars eventually puff out their

atmospheres to form a ghostly glowing cloud

of gas – a ‘planetary nebula’ – while the core

shrinks. These were once thought to be mostly

spherical, but some possess bipolar jets.

This, theorises eric Blackman of the University

of rochester in New york, could be due to the

gravitational infuence of a companion star or

massive planet. The crucial factor is that the pair

must be very close together.

www.rochester.eduimaged by the Hubble Space Telescope, this pre-planetary nebula’s bipolar jets are clear to see

Bulletin APRIL 17


Heavy isotope titanium-44, imaged by NuSTAR and shown in blue, is clearly clustered at the centre of the explosion

What makes stars explode?NASA’s NuSTAR may have uncovered why stars become violently unstable

The mysTery of how stars explode might fnally

be solved. X-ray observations taken by NAsA’s

Nuclear spectroscopic Telescope Array (NusTAr)

suggest material in soon-to-explode stars sloshes

around violently, energising a shock wave

that blows the star to smithereens.

NusTAr was launched into

low-earth orbit in June

2012. Now it has created

the frst map of

radioactive material

in a supernova

remnant,

Cassiopeia A,

which lies

about 11,000

lightyears

from us.

Cassiopeia A

formed when

a massive star

exploded after

running out of

fuel; the light of this

detonation reached

earth roughly 300 years

ago. During the blast, high

temperatures made lighter

elements fuse into heavier ones,

and now NusTAr has created a

map of one of the heavy isotopes

in Cassiopeia A, titanium-44.

The map resolves some puzzles about

supernovae. During the explosion, a shock wave

somehow blasts the star apart, yet previous

computer simulations of this process failed to

replicate this. Instead they suggested that the

NA

SA

/JPL

-CA

LteC

h/C

XC

/SA

O,

NA

SA

/eSA

& V

ALe

Nti

N B

uJA

rr

ABA

L (O

BSer

VA

tOriO

AStr

ON

Om

iCO

NA

CiO

NA

L/SPA

iN)

NA

SA

/h

uBBLe

/StS

Ci,

uSG

S

main shock wave would stall, preventing the star

from shattering. NusTAr revealed that titanium

is concentrated in clumps at Cassiopeia A’s centre.

Astronomers conclude from this that material in

the former star sloshed around, re-energising

the shock wave that fnally made it

blast off its outer layers.

“stars are spherical

balls of gas, so you

might think that

when they end their

lives and explode,

that explosion

would look like

a uniform ball

expanding

out,” says

NusTAr

scientist fiona

harrison from

the California

Institute of

Technology. “our

new results show

how the explosion’s

engine is distorted,

possibly because the inner

regions literally slosh around

before detonating.”

The NusTAr map also casts

doubt on another model of

supernovae, in which a star

rotates rapidly enough to launch energetic jets

of gas that drive the explosion. Although there’s

evidence of jets in Cassiopeia A, NusTAr’s

observations suggest they did not trigger the blast.

www.nasa.gov/nustar

JoiN THe HuNT foR plANeTARy SySTemSNASA is asking for help in fnding embryonic planetary systems in observations from the Wide-feld Infrared Survey Explorer (WISE) spacecraft. There may be thousands lurking in the data, but they can only be found through human inspection, which poses a huge challenge.

“Volunteers will help the astronomical community discover new planetary nurseries that will become future targets for NASA’s Hubble Space Telescope and its successor, the James Webb Space Telescope,” says James Garvin from NASA’s Goddard Space Flight Center in Maryland.www.diskdetective.org

news in

brief

AT lAST: A GlobAl mAp of GANymedeMore than four centuries after its discovery, the Solar System’s largest moon – Jupiter’s Ganymede – fnally has a global map. Wes Patterson from the Johns Hopkins University in Maryland and colleagues compiled it using images from NASA’s Voyager and Galileo missions.

HoW STARS CARVE STRANGE NEbUlAELow-mAss sTArs like the sun can end their

lives as double-lobed planetary nebulae if they

have close companions, a new study suggests.

sun-like stars eventually puff out their

atmospheres to form a ghostly glowing cloud

of gas – a ‘planetary nebula’ – while the core

shrinks. These were once thought to be mostly

spherical, but some possess bipolar jets.

This, theorises eric Blackman of the University

of rochester in New york, could be due to the

gravitational infuence of a companion star or

massive planet. The crucial factor is that the pair

must be very close together.

www.rochester.eduimaged by the Hubble Space Telescope, this pre-planetary nebula’s bipolar jets are clear to see

Events season continues. At the

end of March (28th-31st) we are

at Kelling Heath in Norfolk for

the Spring Equinox Star Party -

see www.starparty.org Then April

26th-27th sees us at Astrocamp

in Wales - great fun, for details

see www.astrocamp.org.uk

June 7-8th is the International

Astronomy Show in Warwick-

shire - www.ukastroshow.com

- and Sunday June 22nd will be

International Sun Day - and we

will be in Regent’s Park in cen-

tral London with the Baker Street

Irregular Astronomers - see

www.bakerstreetastro.org.uk

Rest assured that we at The

Widescreen Centre learn from

every show that we do, and at all

the events we have lined up for

2014 (including the SW Astron-

omy Fair, Autumn Kelling Heath,

Kielder Star Camp and more..)

we will have some very special

offers, great new products, and

the best advice there is. Visit

www.widescreen-centre.co.uk

The Widescreen CentreAll the major brands

under one roof!

London’s Astronomy Showroom,

In Marylebone since 1971.

The widest range of telescopes

and Astronomy products in the

UK - and the best advice in

the industry, from experienced,

enthusiastic staff with a practical,

thorough understanding of how

to get you out there exploring the

Universe the way you want.

London’s Coolest

Astronomical Society

Kelling Heath Star Party, Norfolk

In Store. In the feld. At exhibitions.

At Star Parties. In the Park. On site.

Online. By phone. By email.

Relentlessly bringing you the latest,

the greatest, and the best value

Astronomy products on the market.

We’re always happy to talk Astronomy.

Whatever the season.

Widescreen supports The Baker Street Irregular Astronomers - London’s coolest Astronomical Society - meeting monthly in Regent’s Park. Chance to

Check out our products after dark and learn in a fun, friendly environment about this great hobby. See www.bakerstreetastro.org.uk for more details.

Power Lander

intro £2699.00

Exclusively

from

020

7935

2580

For details of the next meeting

see www.bakerstreetastro.org.uk

Sky-Watcher

200DPS HEQ5

Pro - £CALL

Lunar photo by Widescreen customer Richard Maun. Main BSIA image by Tom Kerss

Events season continues. At the

end of March (28th-31st) we are

at Kelling Heath in Norfolk for

the Spring Equinox Star Party -

see www.starparty.org Then April

26th-27th sees us at Astrocamp

in Wales - great fun, for details

see www.astrocamp.org.uk

June 7-8th is the International

Astronomy Show in Warwick-

shire - www.ukastroshow.com

- and Sunday June 22nd will be

International Sun Day - and we

will be in Regent’s Park in cen-

tral London with the Baker Street

Irregular Astronomers - see

www.bakerstreetastro.org.uk

Rest assured that we at The

Widescreen Centre learn from

every show that we do, and at all

the events we have lined up for

2014 (including the SW Astron-

omy Fair, Autumn Kelling Heath,

Kielder Star Camp and more..)

we will have some very special

offers, great new products, and

the best advice there is. Visit

www.widescreen-centre.co.uk

The Widescreen CentreAll the major brands

under one roof!

London’s Astronomy Showroom,

In Marylebone since 1971.

The widest range of telescopes

and Astronomy products in the

UK - and the best advice in

the industry, from experienced,

enthusiastic staff with a practical,

thorough understanding of how

to get you out there exploring the

Universe the way you want.

London’s Coolest

Astronomical Society

Kelling Heath Star Party, Norfolk

In Store. In the feld. At exhibitions.

At Star Parties. In the Park. On site.

Online. By phone. By email.

Relentlessly bringing you the latest,

the greatest, and the best value

Astronomy products on the market.

We’re always happy to talk Astronomy.

Whatever the season.

Widescreen supports The Baker Street Irregular Astronomers - London’s coolest Astronomical Society - meeting monthly in Regent’s Park. Chance to

Check out our products after dark and learn in a fun, friendly environment about this great hobby. See www.bakerstreetastro.org.uk for more details.

Power Lander

intro £2699.00

Exclusively

from

020

7935

2580

For details of the next meeting

see www.bakerstreetastro.org.uk

Sky-Watcher

200DPS HEQ5

Pro - £CALL

Lunar photo by Widescreen customer Richard Maun. Main BSIA image by Tom Kerss

what’s on april 19


Our pick of the best events from around the UK

What’s on

AstroCamp 2014Brecon Beacons, Wales, 26-29 April

Twice a year, the small village of Cwmdu in the Brecon Beacons is invaded by astronomers when AstroCamp rolls into town. This month, the popular star party returns to this beautiful site – a designated Dark Sky Reserve.

As well as observing at night, the event will include talks, workshops and a pub quiz with astronomical prizes – including telescopes – to be won.

All activities plus a pitch for your tent or caravan are included in the price of a ticket (electricity can be supplied to your pitch for an extra cost) but if you’re planning on taking part in the evening observing festivities it’s worth bringing your own equipment; and remember, torches should be red light only. Tickets start at £38 per adult and £15 for children. www.astrocamp.org.uk

Whether you pitch or park, fnding room to pack your own equipment is advised

PICK OF THE MONTH

mArsThis month The Sky at Night will journey across the face of our planetary neighbour – Mars. For more than 10 years we’ve had a continuous presence on Mars, thanks to the Opportunity, Spirit and Curiosity rovers. Together they have changed our understanding of the Red Planet and redefned our search for extraterrestrial life.

*Check www.radiotimes.com as times may vary

Four, 13 April, 10pm (repeated Four, 17 April, 7.30pm)*

behind the scenes

The sky AT NighT iN APriL

ast

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am

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ick

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hin

kst

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asa

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iv

more listings online

visit our website at www.skyatnightmagazine.com/whats-on for the full list of this month’s events from around the country.

to ensure that your talks, observing evenings and star parties are included, please submit your event by flling in the submission form at the bottom of the page.

yuri’s Nightseething Observatory, Thwaite st mary, Norfolk, 12 April, 2pm onwards

Norwich Astronomical Society is just one of the astronomy groups in the UK hosting a Yuri’s Night party to celebrate the frst manned spacefight. With solar viewing, rocket making and more during the day,

plus observing at night, this is an event for all the family. Tickets cost £3.50 for adults and £1.50 for children. You can fnd out more at www.norwichastro.org.uk.

Active galactic NucleiAyton Village hall, scarborough 11 April, 7.30pm

Hear Dr Stuart Lumsden from Leeds University’s School of Physics and Astronomy discussing supermassive black holes at Scarborough and Ryedale Astronomical

Society this month. Discover how these celestial leviathans grow and the dramatic effect they have on the galaxies around them. Tickets are free for members, £2 for non-members. Visit www.scarborough-ryedale-as.org.uk.

ground-level images taken by the martian rovers have given us new insights

Being Caroline herschelThe herschel museum of Astronomy, Bath, 16 April to 18 December

This new exhibition at the Herschel Museum of Astronomy celebrates the life and work of William Herschel’s sister Caroline, an accomplished musician and astronomer in her own right. Admission is included in the general museum entry fee, which is £6 for adults and £3 for children. Find out more at www.herschelmuseum.org.uk.

what’s on april 19


Our pick of the best events from around the UK

What’s on

AstroCamp 2014Brecon Beacons, Wales, 26-29 April

Twice a year, the small village of Cwmdu in the Brecon Beacons is invaded by astronomers when AstroCamp rolls into town. This month, the popular star party returns to this beautiful site – a designated Dark Sky Reserve.

As well as observing at night, the event will include talks, workshops and a pub quiz with astronomical prizes – including telescopes – to be won.

All activities plus a pitch for your tent or caravan are included in the price of a ticket (electricity can be supplied to your pitch for an extra cost) but if you’re planning on taking part in the evening observing festivities it’s worth bringing your own equipment; and remember, torches should be red light only. Tickets start at £38 per adult and £15 for children. www.astrocamp.org.uk

Whether you pitch or park, fnding room to pack your own equipment is advised

PICK OF THE MONTH

mArsThis month The Sky at Night will journey across the face of our planetary neighbour – Mars. For more than 10 years we’ve had a continuous presence on Mars, thanks to the Opportunity, Spirit and Curiosity rovers. Together they have changed our understanding of the Red Planet and redefned our search for extraterrestrial life.

*Check www.radiotimes.com as times may vary

Four, 13 April, 10pm (repeated Four, 17 April, 7.30pm)*

behind the scenes

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more listings online

visit our website at www.skyatnightmagazine.com/whats-on for the full list of this month’s events from around the country.

to ensure that your talks, observing evenings and star parties are included, please submit your event by flling in the submission form at the bottom of the page.

yuri’s Nightseething Observatory, Thwaite st mary, Norfolk, 12 April, 2pm onwards

Norwich Astronomical Society is just one of the astronomy groups in the UK hosting a Yuri’s Night party to celebrate the frst manned spacefight. With solar viewing, rocket making and more during the day,

plus observing at night, this is an event for all the family. Tickets cost £3.50 for adults and £1.50 for children. You can fnd out more at www.norwichastro.org.uk.

Active galactic NucleiAyton Village hall, scarborough 11 April, 7.30pm

Hear Dr Stuart Lumsden from Leeds University’s School of Physics and Astronomy discussing supermassive black holes at Scarborough and Ryedale Astronomical

Society this month. Discover how these celestial leviathans grow and the dramatic effect they have on the galaxies around them. Tickets are free for members, £2 for non-members. Visit www.scarborough-ryedale-as.org.uk.

ground-level images taken by the martian rovers have given us new insights

Being Caroline herschelThe herschel museum of Astronomy, Bath, 16 April to 18 December

This new exhibition at the Herschel Museum of Astronomy celebrates the life and work of William Herschel’s sister Caroline, an accomplished musician and astronomer in her own right. Admission is included in the general museum entry fee, which is £6 for adults and £3 for children. Find out more at www.herschelmuseum.org.uk.

A pAssion for spAce april 21


The famous

tagline used to

advertise the

1979 flm

Alien was “In space no

one can hear you

scream”. Technically,

that’s true. In the

vacuum of space sound

waves are unable to

propagate as there’s no

medium to carry them.

So why are the sounds of

the Universe the subject

of March’s episode of

The Sky at Night? Well,

it’s because sound has

helped us discover some

amazing things about

celestial bodies and may

help us solve one of the mysteries that

continues to puzzle us.

Good vibrationsMy frst encounter with sounds in space

came with the Cassini-Huygens space

probe. After its seven-year journey of

more than 1.5 billion km the spacecraft

arrived at Saturn and released the Huygens

lander, which tumbled through the dense

atmosphere of Saturn’s moon Titan. It

sent back sounds and images as it fell, and

I remember being amazed at hearing

sounds from bodies in our Solar System.

Now we’re doing more with sound and

we don’t have to send up a spacecraft to

detect it, as vibrations emanating from a

body can sometimes be seen. In the early

1960s oscillations were observed over the thin

kst

oc

k

a passion for

Listen carefully: sound could help us solve one of the enduring mysteries of the Universe

surface of the Sun. The oscillations were

detected by measurements of red or blue

shifts of small surface patches, which were

able to tell us if the area being observed

was moving towards or away from us.

The source of the oscillations was

unknown at the time and it was suggested

that they were due to sound waves

generated inside the Sun. Observations

later confrmed this and the science of

helioseismology was born. Just as

seismologists here on Earth can use

tectonic events to probe our planet’s

interior, so similar techniques can be used

to probe the Sun and reveal structure that

we otherwise could not see.

Now it’s hoped that oscillations

generated by other objects in space could

be used to detect one of the true enigmas

of modern physics:

gravitational waves.

The demise of a star

can leave behind some

interesting debris. Some

leave a white dwarf,

some collapse to form

black holes while others

turn supernova and can

leave behind a neutron

star – a body the size of

a city (~10km) with the

mass a little less than

1.5 times that of our Sun.

A pulsar is a type of

neutron star that emits a

beam of radiation that

appears to pulsate – a bit

like the light from a

lighthouse – due to a

misalignment between its rotational and

magnetic axes. If this beam is in the right

orientation, its radio waves can be detected

on Earth and heard as a clicking sound.

The frequency of the clicking can be

incredibly stable. So stable, in fact, that it

may enable us to detect a gravitational

wave, as a wave’s presence could cause a

minuscule delay in the arrival the pulse’s

clicks on Earth. If a delay is found in a

number of pulsars then the passing of a

gravitational wave could be detected.

So even if screaming is futile, listening is

not, as the detection of sound waves and

oscillations out there is giving us new

insight into the Universe around us.

Maggie Aderin-Pocock is a space scientist and co-presenter of The Sky at Night

with Maggie Aderin-Pocock

S

The audible ‘footprint’ of a gravitational wave could be detected in a pulsar’s radiation beam

A pAssion for spAce april 21


The famous

tagline used to

advertise the

1979 flm

Alien was “In space no

one can hear you

scream”. Technically,

that’s true. In the

vacuum of space sound

waves are unable to

propagate as there’s no

medium to carry them.

So why are the sounds of

the Universe the subject

of March’s episode of

The Sky at Night? Well,

it’s because sound has

helped us discover some

amazing things about

celestial bodies and may

help us solve one of the mysteries that

continues to puzzle us.

Good vibrationsMy frst encounter with sounds in space

came with the Cassini-Huygens space

probe. After its seven-year journey of

more than 1.5 billion km the spacecraft

arrived at Saturn and released the Huygens

lander, which tumbled through the dense

atmosphere of Saturn’s moon Titan. It

sent back sounds and images as it fell, and

I remember being amazed at hearing

sounds from bodies in our Solar System.

Now we’re doing more with sound and

we don’t have to send up a spacecraft to

detect it, as vibrations emanating from a

body can sometimes be seen. In the early

1960s oscillations were observed over the thin

kst

oc

k

a passion for

Listen carefully: sound could help us solve one of the enduring mysteries of the Universe

surface of the Sun. The oscillations were

detected by measurements of red or blue

shifts of small surface patches, which were

able to tell us if the area being observed

was moving towards or away from us.

The source of the oscillations was

unknown at the time and it was suggested

that they were due to sound waves

generated inside the Sun. Observations

later confrmed this and the science of

helioseismology was born. Just as

seismologists here on Earth can use

tectonic events to probe our planet’s

interior, so similar techniques can be used

to probe the Sun and reveal structure that

we otherwise could not see.

Now it’s hoped that oscillations

generated by other objects in space could

be used to detect one of the true enigmas

of modern physics:

gravitational waves.

The demise of a star

can leave behind some

interesting debris. Some

leave a white dwarf,

some collapse to form

black holes while others

turn supernova and can

leave behind a neutron

star – a body the size of

a city (~10km) with the

mass a little less than

1.5 times that of our Sun.

A pulsar is a type of

neutron star that emits a

beam of radiation that

appears to pulsate – a bit

like the light from a

lighthouse – due to a

misalignment between its rotational and

magnetic axes. If this beam is in the right

orientation, its radio waves can be detected

on Earth and heard as a clicking sound.

The frequency of the clicking can be

incredibly stable. So stable, in fact, that it

may enable us to detect a gravitational

wave, as a wave’s presence could cause a

minuscule delay in the arrival the pulse’s

clicks on Earth. If a delay is found in a

number of pulsars then the passing of a

gravitational wave could be detected.

So even if screaming is futile, listening is

not, as the detection of sound waves and

oscillations out there is giving us new

insight into the Universe around us.

Maggie Aderin-Pocock is a space scientist and co-presenter of The Sky at Night

with Maggie Aderin-Pocock

S

The audible ‘footprint’ of a gravitational wave could be detected in a pulsar’s radiation beam

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DARK SKY

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Located deep in the

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close to the Sir Patrick

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Kielder Water and

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01434 240 382 • www.thepheasantinn.com

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THe PHeasanT InnKIelder WaTer

This B&B accommodation

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ma

in ill

ustr

ati

on

by m

ark

ga

rli

ck

, ph

oto

: Em

ma

sa

mm

s

Sitting at the controls of the

Cruiser globe, i’m gripped by an urge

to experience the unfathomable infnity

of the Universe. Such an overused word,

‘awesome’: reasonably priced Florida

doughnuts may be described in a twangy

Miley Cyrus tone as ‘awesome’, but the

vastness of the Universe is awesomeness

in the true sense. i hit launch and head

off in a random direction.

Soon the Cruiser globe’s scanning

systems indicate an unknown object.

i feel a concern similar to Captain

Phillips when he spotted the Somali

pirates looming. But drawing closer,

the great mystery is revealed: this object

is a rogue planet. a solitary world

drifting through the Universe, devoid

of a parent star.

there’s a tantalising blend of

fascination and foreboding on

approaching this world that was

somehow ejected from its system,

perhaps by a gravitational encounter

with another object. it’s estimated there

are around two rogue planets for every

star in the galaxy. Some scientists

think there may be many more.

a technique called gravitational

microlensing is used to detect rogue

planets back on earth, but there’s no need

for such methods today as this particular

rogue planet is right in front of me. i land

immediately to experience the feeling of

this lonesome world.

the view from the surface is a palette

of charcoal grey and opaque blackness,

like my grandmother’s monochrome

Pye tV with the brightness at minimum.

this is a rocky world interspersed with

features resembling massive lakes of ice.

if there’s radioactive decay happening

in the planet’s core, it might generate

enough heat for the lakes to be liquifed

deeper down.

there are those who believe it’s

possible for earth-sized wandering

planets like this one to retain an

atmosphere, perhaps of thick hydrogen.

Combine this with enough subterranean

geological activity and there could be

suffcient warmth generated to support

life. these disconnected planets are not

without the most intriguing potential.

this alien sky of the deepest blackness

has stars so magnifcently piercing that

they cast shadows. it’s novel to notice that

the stars in this rogue planet’s sky never

move. Very soon it’s disconcerting, even

frustrating that the entire night sky here is

an unvarying, motionless mural. Due to

not being in a conventional orbit and

because any rotation of this planet on its

axis has become so imperceptibly slow, the

stars in this alien sky wouldn’t appear to

change in an entire human lifetime. Sir

Patrick would’ve had this dark sky entirely

observed, sketched and catalogued in

under a week, leaving him plenty of time

for cricket and a g&t in the pavilion.

this desolate place conveys a strange

feeling of sadness. it seems impossible

not to project human emotions onto this

environment. Feeling pity for a planet:

what a bizarre sensation. i decide to

name this lonely world ‘Obsidiana’.

in my imagination i hear the piano

theme from the Bill Bixby-era Incredible

Hulk tV show as the rogue planet

Obsidiana drifts silently through the

Universe in her own sweet way.

Jon Culshaw is a comedian, impressionist and occasional guest on The Sky at Night

ex planetjon culshaw’s

exoplanet excursions april 23

jon fnds himself on a world so steeped in darkness that the stars cast shadows

excursions

ma

in ill

ustr

ati

on

by m

ark

ga

rli

ck

, ph

oto

: Em

ma

sa

mm

s

Sitting at the controls of the

Cruiser globe, i’m gripped by an urge

to experience the unfathomable infnity

of the Universe. Such an overused word,

‘awesome’: reasonably priced Florida

doughnuts may be described in a twangy

Miley Cyrus tone as ‘awesome’, but the

vastness of the Universe is awesomeness

in the true sense. i hit launch and head

off in a random direction.

Soon the Cruiser globe’s scanning

systems indicate an unknown object.

i feel a concern similar to Captain

Phillips when he spotted the Somali

pirates looming. But drawing closer,

the great mystery is revealed: this object

is a rogue planet. a solitary world

drifting through the Universe, devoid

of a parent star.

there’s a tantalising blend of

fascination and foreboding on

approaching this world that was

somehow ejected from its system,

perhaps by a gravitational encounter

with another object. it’s estimated there

are around two rogue planets for every

star in the galaxy. Some scientists

think there may be many more.

a technique called gravitational

microlensing is used to detect rogue

planets back on earth, but there’s no need

for such methods today as this particular

rogue planet is right in front of me. i land

immediately to experience the feeling of

this lonesome world.

the view from the surface is a palette

of charcoal grey and opaque blackness,

like my grandmother’s monochrome

Pye tV with the brightness at minimum.

this is a rocky world interspersed with

features resembling massive lakes of ice.

if there’s radioactive decay happening

in the planet’s core, it might generate

enough heat for the lakes to be liquifed

deeper down.

there are those who believe it’s

possible for earth-sized wandering

planets like this one to retain an

atmosphere, perhaps of thick hydrogen.

Combine this with enough subterranean

geological activity and there could be

suffcient warmth generated to support

life. these disconnected planets are not

without the most intriguing potential.

this alien sky of the deepest blackness

has stars so magnifcently piercing that

they cast shadows. it’s novel to notice that

the stars in this rogue planet’s sky never

move. Very soon it’s disconcerting, even

frustrating that the entire night sky here is

an unvarying, motionless mural. Due to

not being in a conventional orbit and

because any rotation of this planet on its

axis has become so imperceptibly slow, the

stars in this alien sky wouldn’t appear to

change in an entire human lifetime. Sir

Patrick would’ve had this dark sky entirely

observed, sketched and catalogued in

under a week, leaving him plenty of time

for cricket and a g&t in the pavilion.

this desolate place conveys a strange

feeling of sadness. it seems impossible

not to project human emotions onto this

environment. Feeling pity for a planet:

what a bizarre sensation. i decide to

name this lonely world ‘Obsidiana’.

in my imagination i hear the piano

theme from the Bill Bixby-era Incredible

Hulk tV show as the rogue planet

Obsidiana drifts silently through the

Universe in her own sweet way.

Jon Culshaw is a comedian, impressionist and occasional guest on The Sky at Night

ex planetjon culshaw’s

exoplanet excursions april 23

jon fnds himself on a world so steeped in darkness that the stars cast shadows

excursions

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free one month trialto the digital edition


The perfect addition to your stargazing, BBC Sky at Night Magazine is your practical guide to astronomy, helping you to discover the night skies, understand the Universe around us and

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The perfect addition to your stargazing, BBC Sky at Night Magazine is your practical guide to astronomy, helping you to discover the night skies, understand the Universe around us and

learn exciting techniques for using your telescope.

have BBC Sky at Night Magazine delivered straight to your device

When you take out a one month free trial* Simply return to homepage to subscribe

*After your one month trial your subscription will continue at £2.99 per month


26

Interactive


Email us at [email protected]

message of the month Mad about MaggieThe more I see her on TV, the more my admiration

for Dr Maggie Aderin-Pocock grows. Her obvious

enthusiasm is contagious and engaging – she lights

up the screen every time she appears. Something

she seems to share with the late, great Sir Patrick is

her ability to speak plain English, even when going

into technical detail.

When I heard she was to become a Sky at Night

presenter in February, I was thrilled. I believe she

will be a great ambassador for astronomy and a

superb role model for the young. I’m looking

forward to the next episode of The Sky at Night

and wish Maggie all the best.

Also, thanks for Stephen Tonkin’s Binocular

tour, it’s been a godsend on these stormy nights

whenever there’s been a brief break in the clouds.

The skies seem to have been really clear despite

all the foul weather!

George Futers, Peebles

We agree George, don’t forget to read Maggie’s excellent column on page 21. – Ed

Catch them youngOn Sunday morning recently I had an hour free

before lunch to read BBC Sky at Night Magazine. But

within 10 minutes that idea was shattered, as my

daughter arrived for a visit, bringing my seven-

month-old granddaughter Emily with her. Emily

made herself comfortable on my knee and

proceeded to cast her eyes over the page I was

reading. After a while, she

lost interest and opted for

the more interesting task of

riding the hobbyhorse. I did

my best to guide her towards

the astronomy path, but

maybe it was a bit too early!

Geoff Wadsley,

Wellingborough

Maybe seven months is a bit ambitious Geoff, but don’t give up yet! – Ed

new uses for old scopesHow saddened I was to learn via Govert Schilling’s

article (‘Observing in an uncertain future’, March)

just how many perfectly serviceable – and sizeable

– telescopes in Chile are being mothballed or

decommissioned. What a waste.

I imagine I’m not the only reader to have made a

connection between that and Kieron Allen’s piece

about robotic scopes (‘Imaging from afar’) later in

the same issue. Couldn’t some of the Chilean

observatories be added to those that are already

remotely accessible to fee-paying users? Although

perhaps there’s another potential use these

telescopes could be put to?

There is a growing realisation and acceptance

that near-Earth objects (NEOs) are far more

numerous than previously thought, and that

even relatively small ones are capable of doing

extreme damage to our planet. Britain has its own

Spaceguard Centre on the English-Welsh border

and there are others scattered around the world

Emails • lEttErs • twEEts • FaCEBOOK

The ‘Message of the Month’ writer will receive four top titles courtesy of astronomy publisher Philip’s. Heather Couper and Nigel Henbest’s Stargazing 2014 is a month-by-month guide to the year and you’ll be able to fnd all the best sights with Patrick Moore’s The Night Sky. Stargazing with Binoculars by Robin Scagell and David Frydman contains equipment and observing guides, and you’ll be viewing planets, galaxies and more with Storm Dunlop’s Practical Astronomy.

this month’s top prize: four Philip’s books

Þ Dr Maggie Aderin-Pocock is skilled at communicating her knowledge of and enthusiasm for astronomy

þ Seven-month-old Emily gets to grips with BBC Sky at Night Magazine

bbc

26

Interactive


Email us at [email protected]

message of the month Mad about MaggieThe more I see her on TV, the more my admiration

for Dr Maggie Aderin-Pocock grows. Her obvious

enthusiasm is contagious and engaging – she lights

up the screen every time she appears. Something

she seems to share with the late, great Sir Patrick is

her ability to speak plain English, even when going

into technical detail.

When I heard she was to become a Sky at Night

presenter in February, I was thrilled. I believe she

will be a great ambassador for astronomy and a

superb role model for the young. I’m looking

forward to the next episode of The Sky at Night

and wish Maggie all the best.

Also, thanks for Stephen Tonkin’s Binocular

tour, it’s been a godsend on these stormy nights

whenever there’s been a brief break in the clouds.

The skies seem to have been really clear despite

all the foul weather!

George Futers, Peebles

We agree George, don’t forget to read Maggie’s excellent column on page 21. – Ed

Catch them youngOn Sunday morning recently I had an hour free

before lunch to read BBC Sky at Night Magazine. But

within 10 minutes that idea was shattered, as my

daughter arrived for a visit, bringing my seven-

month-old granddaughter Emily with her. Emily

made herself comfortable on my knee and

proceeded to cast her eyes over the page I was

reading. After a while, she

lost interest and opted for

the more interesting task of

riding the hobbyhorse. I did

my best to guide her towards

the astronomy path, but

maybe it was a bit too early!

Geoff Wadsley,

Wellingborough

Maybe seven months is a bit ambitious Geoff, but don’t give up yet! – Ed

new uses for old scopesHow saddened I was to learn via Govert Schilling’s

article (‘Observing in an uncertain future’, March)

just how many perfectly serviceable – and sizeable

– telescopes in Chile are being mothballed or

decommissioned. What a waste.

I imagine I’m not the only reader to have made a

connection between that and Kieron Allen’s piece

about robotic scopes (‘Imaging from afar’) later in

the same issue. Couldn’t some of the Chilean

observatories be added to those that are already

remotely accessible to fee-paying users? Although

perhaps there’s another potential use these

telescopes could be put to?

There is a growing realisation and acceptance

that near-Earth objects (NEOs) are far more

numerous than previously thought, and that

even relatively small ones are capable of doing

extreme damage to our planet. Britain has its own

Spaceguard Centre on the English-Welsh border

and there are others scattered around the world

Emails • lEttErs • twEEts • FaCEBOOK

The ‘Message of the Month’ writer will receive four top titles courtesy of astronomy publisher Philip’s. Heather Couper and Nigel Henbest’s Stargazing 2014 is a month-by-month guide to the year and you’ll be able to fnd all the best sights with Patrick Moore’s The Night Sky. Stargazing with Binoculars by Robin Scagell and David Frydman contains equipment and observing guides, and you’ll be viewing planets, galaxies and more with Storm Dunlop’s Practical Astronomy.

this month’s top prize: four Philip’s books

Þ Dr Maggie Aderin-Pocock is skilled at communicating her knowledge of and enthusiasm for astronomy

þ Seven-month-old Emily gets to grips with BBC Sky at Night Magazine

bbc

letters APRIL 27


Have your say at http://twitter.com/skyatnightmag

@skyatnightmag

asked: How have

you made the most of the

rare breaks in the clouds

this stormy season?

@Ripley180924609

By being able to watch

as the #ISS passed over

– frst time I’ve ever seen

it and it was fab. :-)

@sjb_astro

Left scope all set up in

garage ready to quickly

take out during rare

clear spells. Observed

SN 2014J, Jupiter and

the Moon.

@thephildoyle

I read a billion reviews

and blogs to shortlist the

best planetary camera,

new or used, for circa

£200.

@EardleyTony

Imaged a new once-

in-a-lifetime supernova

in M82.

@haddockman83

Had a good look at the

Moon through binoculars

and managed to see the

rings of Jupiter through

a telescope.

@smyth791

As soon as the clouds

break, I have been out

looking at Jupiter and

its amazing moons. :)

the big

debate

EDITORIALEditor Chris Bramley Art Editor Steve MarshProduction Editor Kev Lochun Online Editor Kieron AllenStaff Writer Elizabeth PearsonReviews Editor Paul Money

CONTRIBUTORS Paul Abel, Sean Blair, Paul F Cockburn, Adam Crute, Maggie Aderin-Pocock, Jon Culshaw, Lewis Dartnell, Glenn Dawes, Mark Garlick, Will Gater, Alastair Gunn, Nicky Guttridge, Carol Lakomiak, Pete Lawrence, Martin Lewis, Chris Lintott, Hazel Muir, Steve Richards, Steve Sayers, Paul Sutherland, Stephen Tonkin, Emily Winterburn

ADVERTISING SALESAdvertising Director Caroline HerbertAdvertising Managers Steve Grigg (0117 314 8365), Tony Robinson (0117 314 8811)Inserts Laurence Robertson (00 353 87 690 2208)

PRODUCTIONProduction Director Sarah Powell Production Manager Derrick AndrewsAd Services Manager Paul ThorntonAd Co-ordinator Emily ThorneAd Designers Cee Pike, Andrew HobsonReprographics Tony Hunt, Chris Sutch

LICENSINGHead of Licensing and Syndication Joanna Marshall

MARKETINGHead of Circulation Rob Brock Head of Marketing Jacky Perales-MorrisMarketing Executive Chris DayHead of Press and PR Carolyn Wray (0117 314 8812)

PUBLISHINGPublisher Jemima RansomeManaging Director Andy Marshall

MANAGEMENT Chairman Stephen Alexander Deputy Chairman Peter PhippenCEO Tom Bureau

BBC WORLDWIDE, UK PUBLISHINGDirector of UK Publishing Nicholas Brett Head of UK Publishing Chris KerwinHead of Editorial, UK Publishing Jenny PotterUK Publishing Coordinator Eva Abramik [email protected] www.bbcworldwide.com/uk--anz/ukpublishing.aspx

EDITORIAL ADVISORY BOARD Deborah Cohen, Andrew Cohen, Michael Ewing, Julian Hector, John Lynch, Jonathan Renouf

SUBSCRIPTION RATESAnnual subscription rates (inc P&P): UK cheque/credit card £59.88; Europe & Eire

Airmail £69; rest of world airmail £79. To order, call 0844 844 0260

The publisher, editor and authors accept no responsibility in respect of any products, goods or services that may be advertised or referred to in this issue for any errors, omissions, mis-statements or mistakes in any such advertisements or references.

BBC Sky at Night Magazine is published by Immediate Media Company Bristol Limited under licence from BBC Worldwide, who help fund new BBC programmes.

that report newly identifed NEOs to a centre in

Boston, US.My understanding is that there is a

shortage of telescopes that are large enough to

be able to see these smaller objects dedicated

to this important area of observation. I wonder

if the Chilean ones might be pressed

into service?

David Tart, Walsall

Great idea David, it would be real shame to let these historic observatories close down altogether. – Ed

a successful comebackBack in the late 1950s and early 1960s, I was bitten

by the space and astronomy bug. But, as with many

young people, this all came to an end when I

fnished school and went out into the big wide

world. Now, newly retired, I’ve returned to the fold.

I quickly realised that science and technology

have moved on a great deal in the 50 years since I

last gazed up at the sky, so I began looking around

for a suitable magazine that would help me learn

about astronomy today. That’s when I found BBC

Sky at Night Magazine. Its balance of recurring

sections such as the Guide to the Universe and the

Big Questions, combined with observing tips,

monthly charts and excellent articles have all helped

enormously to rekindle my interest.

With a background in communications, I’ve

decided to delve into the world of radio astronomy.

Apart from anything else, it means I don’t have to

go out into the cold! In the few months that I’ve

been reading your excellent magazine, there hasn’t

been anything on the subject. Do you have any

plans to cover the topic?

Brian Faulkner, Cornwall

I’m glad we’ve been able to help rekindle you passion for astronomy Brian. Keep your eyes peeled for our How to… article on radio meteor observations coming up in next month’s issue. – Ed

Caught on cameraThis is a picture I took with

just my refractor scope and

my camera phone. I didn’t

use any Moon flters.

Alisia Maldon-Stanley (aged 15),

London

What a fantastic shot Alisia, keep going with the astrophotography, you’ve obviously got a talent. – Ed

© Immediate Media Company Bristol Limited 2014ISSN 1745-9869All rights reserved. No part of BBC Sky at Night Magazine may be reproduced in any form or by means either wholly or in part, without prior written permission of the publisher. Not to be re-sold, lent or hired out or otherwise disposed of by way of trade at more than the recommended retail price (subject to VAT in the Republic of Ireland) or in mutilated condition.

Immediate Media Company Bristol Limited is working to ensure that all of its paper is sourced from well-managed forests. This magazine is printed on Forest Stewardship Council (FSC) certifed paper. This magazine can be recycled, for use in newspapers and packaging. Please remove any gifts, samples or wrapping and dispose of it at your local collection point.

.........................................................................................OOPS!• In March 2014’s First Light review of the Celestron Skyris 445C colour imaging camera, the overall score should have been four stars, not three.

READER SURVEY WINNERCongratulations to the winner of our reader survey prize draw in the December 2013 issue. Andy Offord from Stowmarket, Suffolk, wins a 16GB iPad Mini.

letters APRIL 27


Have your say at http://twitter.com/skyatnightmag

@skyatnightmag

asked: How have

you made the most of the

rare breaks in the clouds

this stormy season?

@Ripley180924609

By being able to watch

as the #ISS passed over

– frst time I’ve ever seen

it and it was fab. :-)

@sjb_astro

Left scope all set up in

garage ready to quickly

take out during rare

clear spells. Observed

SN 2014J, Jupiter and

the Moon.

@thephildoyle

I read a billion reviews

and blogs to shortlist the

best planetary camera,

new or used, for circa

£200.

@EardleyTony

Imaged a new once-

in-a-lifetime supernova

in M82.

@haddockman83

Had a good look at the

Moon through binoculars

and managed to see the

rings of Jupiter through

a telescope.

@smyth791

As soon as the clouds

break, I have been out

looking at Jupiter and

its amazing moons. :)

the big

debate

EDITORIALEditor Chris Bramley Art Editor Steve MarshProduction Editor Kev Lochun Online Editor Kieron AllenStaff Writer Elizabeth PearsonReviews Editor Paul Money

CONTRIBUTORS Paul Abel, Sean Blair, Paul F Cockburn, Adam Crute, Maggie Aderin-Pocock, Jon Culshaw, Lewis Dartnell, Glenn Dawes, Mark Garlick, Will Gater, Alastair Gunn, Nicky Guttridge, Carol Lakomiak, Pete Lawrence, Martin Lewis, Chris Lintott, Hazel Muir, Steve Richards, Steve Sayers, Paul Sutherland, Stephen Tonkin, Emily Winterburn

ADVERTISING SALESAdvertising Director Caroline HerbertAdvertising Managers Steve Grigg (0117 314 8365), Tony Robinson (0117 314 8811)Inserts Laurence Robertson (00 353 87 690 2208)

PRODUCTIONProduction Director Sarah Powell Production Manager Derrick AndrewsAd Services Manager Paul ThorntonAd Co-ordinator Emily ThorneAd Designers Cee Pike, Andrew HobsonReprographics Tony Hunt, Chris Sutch

LICENSINGHead of Licensing and Syndication Joanna Marshall

MARKETINGHead of Circulation Rob Brock Head of Marketing Jacky Perales-MorrisMarketing Executive Chris DayHead of Press and PR Carolyn Wray (0117 314 8812)

PUBLISHINGPublisher Jemima RansomeManaging Director Andy Marshall

MANAGEMENT Chairman Stephen Alexander Deputy Chairman Peter PhippenCEO Tom Bureau

BBC WORLDWIDE, UK PUBLISHINGDirector of UK Publishing Nicholas Brett Head of UK Publishing Chris KerwinHead of Editorial, UK Publishing Jenny PotterUK Publishing Coordinator Eva Abramik [email protected] www.bbcworldwide.com/uk--anz/ukpublishing.aspx

EDITORIAL ADVISORY BOARD Deborah Cohen, Andrew Cohen, Michael Ewing, Julian Hector, John Lynch, Jonathan Renouf

SUBSCRIPTION RATESAnnual subscription rates (inc P&P): UK cheque/credit card £59.88; Europe & Eire

Airmail £69; rest of world airmail £79. To order, call 0844 844 0260

The publisher, editor and authors accept no responsibility in respect of any products, goods or services that may be advertised or referred to in this issue for any errors, omissions, mis-statements or mistakes in any such advertisements or references.

BBC Sky at Night Magazine is published by Immediate Media Company Bristol Limited under licence from BBC Worldwide, who help fund new BBC programmes.

that report newly identifed NEOs to a centre in

Boston, US.My understanding is that there is a

shortage of telescopes that are large enough to

be able to see these smaller objects dedicated

to this important area of observation. I wonder

if the Chilean ones might be pressed

into service?

David Tart, Walsall

Great idea David, it would be real shame to let these historic observatories close down altogether. – Ed

a successful comebackBack in the late 1950s and early 1960s, I was bitten

by the space and astronomy bug. But, as with many

young people, this all came to an end when I

fnished school and went out into the big wide

world. Now, newly retired, I’ve returned to the fold.

I quickly realised that science and technology

have moved on a great deal in the 50 years since I

last gazed up at the sky, so I began looking around

for a suitable magazine that would help me learn

about astronomy today. That’s when I found BBC

Sky at Night Magazine. Its balance of recurring

sections such as the Guide to the Universe and the

Big Questions, combined with observing tips,

monthly charts and excellent articles have all helped

enormously to rekindle my interest.

With a background in communications, I’ve

decided to delve into the world of radio astronomy.

Apart from anything else, it means I don’t have to

go out into the cold! In the few months that I’ve

been reading your excellent magazine, there hasn’t

been anything on the subject. Do you have any

plans to cover the topic?

Brian Faulkner, Cornwall

I’m glad we’ve been able to help rekindle you passion for astronomy Brian. Keep your eyes peeled for our How to… article on radio meteor observations coming up in next month’s issue. – Ed

Caught on cameraThis is a picture I took with

just my refractor scope and

my camera phone. I didn’t

use any Moon flters.

Alisia Maldon-Stanley (aged 15),

London

What a fantastic shot Alisia, keep going with the astrophotography, you’ve obviously got a talent. – Ed

© Immediate Media Company Bristol Limited 2014ISSN 1745-9869All rights reserved. No part of BBC Sky at Night Magazine may be reproduced in any form or by means either wholly or in part, without prior written permission of the publisher. Not to be re-sold, lent or hired out or otherwise disposed of by way of trade at more than the recommended retail price (subject to VAT in the Republic of Ireland) or in mutilated condition.

Immediate Media Company Bristol Limited is working to ensure that all of its paper is sourced from well-managed forests. This magazine is printed on Forest Stewardship Council (FSC) certifed paper. This magazine can be recycled, for use in newspapers and packaging. Please remove any gifts, samples or wrapping and dispose of it at your local collection point.

.........................................................................................OOPS!• In March 2014’s First Light review of the Celestron Skyris 445C colour imaging camera, the overall score should have been four stars, not three.

READER SURVEY WINNERCongratulations to the winner of our reader survey prize draw in the December 2013 issue. Andy Offord from Stowmarket, Suffolk, wins a 16GB iPad Mini.

28


This month’s pick of your very best astrophotos

PHOTO

OF THEMONTH

Hotshots

Anna says: “I like this image as it shows just how much dust is around the Orion Complex, the dynamic range of this nebula and the large array of colours in the region that you don’t see well when viewing through an eyepiece. It also shows what can be imaged even with modest equipment given some patience and time.” Equipment: Nikon D7000 DSLR camera, Orion EON 80ED telescope.

BBC Sky at Night Magazine says: “The amount of detail Anna has been able to capture in this pristine image of the Orion Nebula and its surroundings is amazing. We very rarely see wide-feld images of this corner of space that manage, so expertly, to defne the intricate dust lanes on the periphery of the central nebulous region. From vibrant pinks and blues to the pastel, almost muddy, hues of the dust lanes, this is the work of an expert.”

About Anna: “I started astro imaging back in 2008. I was living in a light-polluted area and could not see much through the new scope I had got for Christmas due to all the city lights. Short exposure

images allowed me to make out more than I could through the eyepiece. I got the bug from those frst photographs and have been imaging since.”

The Orion Nebula

ANNA MORRIS, SuFFOLk, 5 DECEMbER 2013

28


This month’s pick of your very best astrophotos

PHOTO

OF THEMONTH

Hotshots

Anna says: “I like this image as it shows just how much dust is around the Orion Complex, the dynamic range of this nebula and the large array of colours in the region that you don’t see well when viewing through an eyepiece. It also shows what can be imaged even with modest equipment given some patience and time.” Equipment: Nikon D7000 DSLR camera, Orion EON 80ED telescope.

BBC Sky at Night Magazine says: “The amount of detail Anna has been able to capture in this pristine image of the Orion Nebula and its surroundings is amazing. We very rarely see wide-feld images of this corner of space that manage, so expertly, to defne the intricate dust lanes on the periphery of the central nebulous region. From vibrant pinks and blues to the pastel, almost muddy, hues of the dust lanes, this is the work of an expert.”

About Anna: “I started astro imaging back in 2008. I was living in a light-polluted area and could not see much through the new scope I had got for Christmas due to all the city lights. Short exposure

images allowed me to make out more than I could through the eyepiece. I got the bug from those frst photographs and have been imaging since.”

The Orion Nebula

ANNA MORRIS, SuFFOLk, 5 DECEMbER 2013

HOTSHOTS APRIL 29


The leaping puma in the Rosette Nebula

kFIR SIMON, GAN-YAvNE, ISRAEL 18,30 AND 31 JANuARY 2014

kfr says: “I like this image because of all the dark nebulae in the lower part of the frame, which resemble a parade of animals.“

Equipment: SbIG ST8300M CCD camera, Altair Astro 8-inch Ritchey-Chrétien astrograph, ASA DDM 60 PRO direct drive mount.

Jupiter and Europa

TOM HOWARD, SuSSEx, 9 DECEMbER 2013

Tom says: “I have never been interested in the expense and extra effort required in using colour flters for imaging. This image showed me what can be achieved with a one-shot colour planetary camera under excellent seeing conditions.”

Equipment: Celestron Skyris 618C CCD camera, Celestron C11 Schmidt-Cassegrain, Sky-Watcher EQ6 mount.

NGC 891

TONY FuNNELL, SuSSEx, NOvEMbER 2013

Tony says: “This is a very popular galaxy that appears as a really dim line visually but develops great detail when it is imaged with a CCD camera.”

Equipment: Atik 314 CCD camera, 8-inch Ritchey-Chrétien telescope, Sky-Watcher EQ6 mount.

HOTSHOTS APRIL 29


The leaping puma in the Rosette Nebula

kFIR SIMON, GAN-YAvNE, ISRAEL 18,30 AND 31 JANuARY 2014

kfr says: “I like this image because of all the dark nebulae in the lower part of the frame, which resemble a parade of animals.“

Equipment: SbIG ST8300M CCD camera, Altair Astro 8-inch Ritchey-Chrétien astrograph, ASA DDM 60 PRO direct drive mount.

Jupiter and Europa

TOM HOWARD, SuSSEx, 9 DECEMbER 2013

Tom says: “I have never been interested in the expense and extra effort required in using colour flters for imaging. This image showed me what can be achieved with a one-shot colour planetary camera under excellent seeing conditions.”

Equipment: Celestron Skyris 618C CCD camera, Celestron C11 Schmidt-Cassegrain, Sky-Watcher EQ6 mount.

NGC 891

TONY FuNNELL, SuSSEx, NOvEMbER 2013

Tony says: “This is a very popular galaxy that appears as a really dim line visually but develops great detail when it is imaged with a CCD camera.”

Equipment: Atik 314 CCD camera, 8-inch Ritchey-Chrétien telescope, Sky-Watcher EQ6 mount.


30

The Milly Way and Venus

LuIS ARGERICH, ARGENTINA, 3 NOvEMbER 2013

Luis says: “Here’s a shot of the Milky Way at dusk with venus and the Moon just in the middle of it. Plenty of frefies decorate the scene. I like how the Milky Way can be seen though the sky is not fully dark.”

Equipment: Canon EOS 6D DSLR camera, 14mm lens.

IC 410, IC 405, IC 417 and NGC 1931

SARA WAGER, vALENCIA, SPAIN, NOvEMbER 2013 TO JANuARY 2014

Sara says: “This mosaic took me two months to complete. It represents a total of 152 30-minute exposures and an integration time of 76 hours. The Flaming Star Nebula, IC 405, is aptly showing as a bright orange fame. The four targets all nestle neatly in the frame.”

Equipment: Atik 460ExM CCD camera, Takahashi FSQ85 telescope, Avalon Linear Fast Reverse equatorial mount.

The Pleiades

TERRY HANCOCk AND RObERT FIELDS, MICHIGAN 13 NOvEMbER AND 28 DECEMbER 2013

Terry says: “Here is a collaborated image of the popular star cluster commonly known as the Seven Sisters. While we continue with awful weather here in Michigan it just makes sense to collaborate – this time using different telescopes and cameras, but with a similar feld of view.”

Equipment: QHY11S monochrome CCD camera, STL 11000 monochrome CCD camera, Takahashi Epsilon-180ED telescope, Takahashi FSQ-106 telescope, Paramount GT-1100S German equatorial mount, Astro-Physics AP900 German equatorial mount.


30

The Milly Way and Venus

LuIS ARGERICH, ARGENTINA, 3 NOvEMbER 2013

Luis says: “Here’s a shot of the Milky Way at dusk with venus and the Moon just in the middle of it. Plenty of frefies decorate the scene. I like how the Milky Way can be seen though the sky is not fully dark.”

Equipment: Canon EOS 6D DSLR camera, 14mm lens.

IC 410, IC 405, IC 417 and NGC 1931

SARA WAGER, vALENCIA, SPAIN, NOvEMbER 2013 TO JANuARY 2014

Sara says: “This mosaic took me two months to complete. It represents a total of 152 30-minute exposures and an integration time of 76 hours. The Flaming Star Nebula, IC 405, is aptly showing as a bright orange fame. The four targets all nestle neatly in the frame.”

Equipment: Atik 460ExM CCD camera, Takahashi FSQ85 telescope, Avalon Linear Fast Reverse equatorial mount.

The Pleiades

TERRY HANCOCk AND RObERT FIELDS, MICHIGAN 13 NOvEMbER AND 28 DECEMbER 2013

Terry says: “Here is a collaborated image of the popular star cluster commonly known as the Seven Sisters. While we continue with awful weather here in Michigan it just makes sense to collaborate – this time using different telescopes and cameras, but with a similar feld of view.”

Equipment: QHY11S monochrome CCD camera, STL 11000 monochrome CCD camera, Takahashi Epsilon-180ED telescope, Takahashi FSQ-106 telescope, Paramount GT-1100S German equatorial mount, Astro-Physics AP900 German equatorial mount.

HOTSHOTS APRIL 31


NGC 6231

HAREL bOREN, NAMIbIA, JuNE 2011

Harel says: “Here’s an image, shot from the kalahari Desert in June 2011, which I have fnally come around to processing. It captures a colourful star feld comprising open cluster NGC 6231 through to the Prawn Nebula.”

Equipment: SbIG ST8300M CCD camera, Newtonian refector, Astro-Physics 1200GTO mount.

Earthshine

RICHARD bAILEY, bRAuNSTON, DECEMbER 2013

Richard says: “I managed to capture this image of earthshine just before the Moon set behind a tree. It was bright and the earthshine really stood out.”

Equipment: Canon EOS 1000D DSLR camera, 80ED refractor.

Sharpless 234 and 237

DAN CROWSON, MISSOuRI, 4 NOvEMbER 2013

Dan says: “Sharpless 234 and 237 are fairly bright emission nebulae located approximately 6,800 lightyears away in Auriga. Sharpless 234 is the nebula near the centre of the image; the cluster of stars is designated as Stock 8. Sharpless 237 is the smaller nebula on the left side of the image. It surrounds open cluster NGC 1931.”

Equipment: Atik 383L+ mono CCD camera, APM 80/470 apo refractor, Sky-Watcher NEQ6 mount.

HOTSHOTS APRIL 31


NGC 6231

HAREL bOREN, NAMIbIA, JuNE 2011

Harel says: “Here’s an image, shot from the kalahari Desert in June 2011, which I have fnally come around to processing. It captures a colourful star feld comprising open cluster NGC 6231 through to the Prawn Nebula.”

Equipment: SbIG ST8300M CCD camera, Newtonian refector, Astro-Physics 1200GTO mount.

Earthshine

RICHARD bAILEY, bRAuNSTON, DECEMbER 2013

Richard says: “I managed to capture this image of earthshine just before the Moon set behind a tree. It was bright and the earthshine really stood out.”

Equipment: Canon EOS 1000D DSLR camera, 80ED refractor.

Sharpless 234 and 237

DAN CROWSON, MISSOuRI, 4 NOvEMbER 2013

Dan says: “Sharpless 234 and 237 are fairly bright emission nebulae located approximately 6,800 lightyears away in Auriga. Sharpless 234 is the nebula near the centre of the image; the cluster of stars is designated as Stock 8. Sharpless 237 is the smaller nebula on the left side of the image. It surrounds open cluster NGC 1931.”

Equipment: Atik 383L+ mono CCD camera, APM 80/470 apo refractor, Sky-Watcher NEQ6 mount.

ENTER TO WIN A PRIzE!

We’ve teamed up with the Widescreen Centre to offer the winner of next month’s best Hotshots image a fantastic prize. The winner will receive an Orion StarShoot Solar System Colour Imager Iv camera, designed for capturing sharp shots of the Moon and planets.

www.widescreen-centre.co.uk • 020 7935 2580

Email your pictures to us at [email protected] or enter online. £99WORTH


32 HOTSHOTS APRIL

The Andromeda Galaxy

GARY ANDERSON, GALLOWAY, 1 NOvEMbER 2013

Gary says: “This is my best image of M31 to date as I always fnd processing galaxies diffcult. The detail in the dust lanes is clear and the core is not blown out, giving a nice natural look.”

Equipment: Canon EOS 1000D DSLR camera, Sky-Watcher 80ED telescope.

The Flame and Horsehead Nebulae

PAuL GORDON, ESSEx, 5 JANuARY 2014

Paul says: “This image is the result of 12 fve-minute exposures at ISO 800.”

Equipment: Canon EOS 1000D DSLR camera, William Optics ZS80 telescope.

The Iris Nebula

MARk GRIFFITH SWINDON 4 DECEMbER 2013

Mark says: “This was one of the frst deep-sky objects I ever tried to image – with poor results, far too diffcult for a beginner! This is my best image of this nebula yet.”

Equipment: Atik 383L+ CCD camera, 8-inch Ritchey-Chrétien telescope, Sky-Watcher NEQ6 PRO mount.

ENTER TO WIN A PRIzE!

We’ve teamed up with the Widescreen Centre to offer the winner of next month’s best Hotshots image a fantastic prize. The winner will receive an Orion StarShoot Solar System Colour Imager Iv camera, designed for capturing sharp shots of the Moon and planets.

www.widescreen-centre.co.uk • 020 7935 2580

Email your pictures to us at [email protected] or enter online. £99WORTH


32 HOTSHOTS APRIL

The Andromeda Galaxy

GARY ANDERSON, GALLOWAY, 1 NOvEMbER 2013

Gary says: “This is my best image of M31 to date as I always fnd processing galaxies diffcult. The detail in the dust lanes is clear and the core is not blown out, giving a nice natural look.”

Equipment: Canon EOS 1000D DSLR camera, Sky-Watcher 80ED telescope.

The Flame and Horsehead Nebulae

PAuL GORDON, ESSEx, 5 JANuARY 2014

Paul says: “This image is the result of 12 fve-minute exposures at ISO 800.”

Equipment: Canon EOS 1000D DSLR camera, William Optics ZS80 telescope.

The Iris Nebula

MARk GRIFFITH SWINDON 4 DECEMbER 2013

Mark says: “This was one of the frst deep-sky objects I ever tried to image – with poor results, far too diffcult for a beginner! This is my best image of this nebula yet.”

Equipment: Atik 383L+ CCD camera, 8-inch Ritchey-Chrétien telescope, Sky-Watcher NEQ6 PRO mount.

It’s a planetary murder mystery: how did the once-wet Mars end up the dusty world it is today Sean Blair asks if we’re any closer to an answer

It’s a planetary murder mystery: how did the once-wet Mars end up the dusty world it is today Sean Blair asks if we’re any closer to an answer

NA

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On 8 April, Mars comes to its

closest point to Earth in its

two-year orbit. Observing

that bright red world holds an

added excitement, as we are looking at a

planet we feel we know intimately. For years,

Martian rovers have transmitted back

views of a place remarkably like home, with

morning mists and blue-tinted sunsets.

It’s a beguiling illusion. If anyone were

to step onto the surface unprotected, the

thin atmosphere would cause the saliva

to boil away from their lips before they

blacked out. Even if they managed to

shout for help, they would be inaudible

from a distance of a few tens of metres.

Never forget Mars is an alien world

– its single most alien element being

the ghostly remnant of an atmosphere.

Surface air pressure is less than one

hundredth that of Earth’s at sea level,

equivalent to an altitude of 35km on our

planet, or three times higher than the

cruising height of a commercial airliner.

If there were suffcient concentrations to

breathe, the air would be poisonous: more

than 95 per cent carbon dioxide, plus

nitrogen, argon and other trace gases.

In 1946, astronomer Gerard Kuiper

identifed carbon dioxide as Mars’s major

atmospheric constituent. Previously it

was assumed Mars had an Earth-like

atmosphere, because of the ‘clouds’ so

frequently sighted, as well as a stubborn

belief in the ‘canals’ that Percival Lowell

– he who founded the Lowell Observatory

in Arizona – was believed to have

observed on the planet’s surface.

Scant remainsInto the 1960s, ground-based spectrographic

observations suggested that the Martian

atmosphere was extremely scant,

something confrmed by radio science

experiments during Mariner 4’s two-

day fyby of the planet in July 1965. That

mission, followed by Mariner 6 and 7

in 1969, charted a cratered Moon-like

world. But a fuller picture was given

in January 1972, from Mariner 9. The

spacecraft actually attained Mars orbit the

previous November, but its observations

were delayed by a planet-wide dust

storm – the

Though the blue-tinted sunsets look homely, conditions on Mars are anything but

It looks desolate now, but the evidence indicates that Mars

was once much more pleasant

>

NA

SA

/JPL

-CA

LteC

h/C

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eLL/

Ariz

oN

A S

tAte

UN

iv,

NA

SA

/JPL

/te

xA

S A

&M

/C

orN

eLL

On 8 April, Mars comes to its

closest point to Earth in its

two-year orbit. Observing

that bright red world holds an

added excitement, as we are looking at a

planet we feel we know intimately. For years,

Martian rovers have transmitted back

views of a place remarkably like home, with

morning mists and blue-tinted sunsets.

It’s a beguiling illusion. If anyone were

to step onto the surface unprotected, the

thin atmosphere would cause the saliva

to boil away from their lips before they

blacked out. Even if they managed to

shout for help, they would be inaudible

from a distance of a few tens of metres.

Never forget Mars is an alien world

– its single most alien element being

the ghostly remnant of an atmosphere.

Surface air pressure is less than one

hundredth that of Earth’s at sea level,

equivalent to an altitude of 35km on our

planet, or three times higher than the

cruising height of a commercial airliner.

If there were suffcient concentrations to

breathe, the air would be poisonous: more

than 95 per cent carbon dioxide, plus

nitrogen, argon and other trace gases.

In 1946, astronomer Gerard Kuiper

identifed carbon dioxide as Mars’s major

atmospheric constituent. Previously it

was assumed Mars had an Earth-like

atmosphere, because of the ‘clouds’ so

frequently sighted, as well as a stubborn

belief in the ‘canals’ that Percival Lowell

– he who founded the Lowell Observatory

in Arizona – was believed to have

observed on the planet’s surface.

Scant remainsInto the 1960s, ground-based spectrographic

observations suggested that the Martian

atmosphere was extremely scant,

something confrmed by radio science

experiments during Mariner 4’s two-

day fyby of the planet in July 1965. That

mission, followed by Mariner 6 and 7

in 1969, charted a cratered Moon-like

world. But a fuller picture was given

in January 1972, from Mariner 9. The

spacecraft actually attained Mars orbit the

previous November, but its observations

were delayed by a planet-wide dust

storm – the

Though the blue-tinted sunsets look homely, conditions on Mars are anything but

It looks desolate now, but the evidence indicates that Mars

was once much more pleasant

>

36


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true nature of the ‘clouds’. Once the dust settled,

Mariner 9 revealed a startlingly Earth-like world,

with layered ice caps, cirrus clouds, and dried-up

food plains and riverbeds.

Around four billion years ago, Mars’s atmosphere

was still dense enough to sustain liquid water on

the surface – the atmosphere was probably denser

than Earth’s, because it receives only less than half

the energy from the Sun as Earth does, and the Sun

shone 30 per cent less brightly at the time. So Mars

exploration became a kind of murder mystery: why

did this initially hospitable planet perish? How was

its atmosphere stolen away?

The 1976 Viking missions flled in details of

the murder scene – including in-situ atmospheric

measurements, though Viking researchers were

themselves beguiled by Mars’s Earth-like appearance.

The thin sky was graded blue in initial lander

images, but calibration checks confrmed airborne

dust actually left it reddish.

Fast forward to today and two new robotic

detectives are en route to join the rovers and

orbiters already at Mars. India’s Mangalyaan,

offcially the Mars Orbiter Mission (MOM), weighs

in at more than a tonne including fuel, although

only 15kg of that mass is scientifc payload. There

are fve instruments aboard, including two focused

on the detection of trace gases deuterium and

methane. But for the new space-faring nation of

India, MOM’s major achievement would simply be

achieving Mars orbital insertion, which is scheduled

for September. Any useful science would be a bonus.

The plot thickensHopes are higher for NASA’s MAVEN (Mars

Atmosphere and Volatile Evolution), also due

to reach the Red Planet in September. This van-

sized spacecraft will focus on particles escaping

from Mars right now, not just by monitoring

the upper atmosphere, but actually descending

into it once per orbit.

“We’re applying previous experience of

aerobraking spacecraft to go down as low as 150km,

which is below the altitude that escape occurs,” says

Bruce Javovsky, MAVEN’s principal investigator.

“Then we’ll be performing fve ‘deep dips’ during

our year-long mission where we go even lower, to

125km, to sample the entire stratifed column of

the upper atmosphere. The Martian atmosphere

is tenuous enough that we aren’t in danger, but

some high-power instruments will be switched

off to avoid damage. Our gull-design solar

wings help ensure aerodynamic stability.

Þ Today we see dried-up lakes; 3.5 billion years ago, we may have seen something more like this

þ Mariner 9, the frst craft to enter Martian orbit, revealed a slew of Earth-like surface features

>

36


Kee

S v

eeN

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S/SC

ieN

Ce

Pho

to L

iBr

ArY

, N

ASA

/JPL

-CA

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3,

NA

SA

, N

ASA

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orN

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iv.)/M

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erSit

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)/Ji

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true nature of the ‘clouds’. Once the dust settled,

Mariner 9 revealed a startlingly Earth-like world,

with layered ice caps, cirrus clouds, and dried-up

food plains and riverbeds.

Around four billion years ago, Mars’s atmosphere

was still dense enough to sustain liquid water on

the surface – the atmosphere was probably denser

than Earth’s, because it receives only less than half

the energy from the Sun as Earth does, and the Sun

shone 30 per cent less brightly at the time. So Mars

exploration became a kind of murder mystery: why

did this initially hospitable planet perish? How was

its atmosphere stolen away?

The 1976 Viking missions flled in details of

the murder scene – including in-situ atmospheric

measurements, though Viking researchers were

themselves beguiled by Mars’s Earth-like appearance.

The thin sky was graded blue in initial lander

images, but calibration checks confrmed airborne

dust actually left it reddish.

Fast forward to today and two new robotic

detectives are en route to join the rovers and

orbiters already at Mars. India’s Mangalyaan,

offcially the Mars Orbiter Mission (MOM), weighs

in at more than a tonne including fuel, although

only 15kg of that mass is scientifc payload. There

are fve instruments aboard, including two focused

on the detection of trace gases deuterium and

methane. But for the new space-faring nation of

India, MOM’s major achievement would simply be

achieving Mars orbital insertion, which is scheduled

for September. Any useful science would be a bonus.

The plot thickensHopes are higher for NASA’s MAVEN (Mars

Atmosphere and Volatile Evolution), also due

to reach the Red Planet in September. This van-

sized spacecraft will focus on particles escaping

from Mars right now, not just by monitoring

the upper atmosphere, but actually descending

into it once per orbit.

“We’re applying previous experience of

aerobraking spacecraft to go down as low as 150km,

which is below the altitude that escape occurs,” says

Bruce Javovsky, MAVEN’s principal investigator.

“Then we’ll be performing fve ‘deep dips’ during

our year-long mission where we go even lower, to

125km, to sample the entire stratifed column of

the upper atmosphere. The Martian atmosphere

is tenuous enough that we aren’t in danger, but

some high-power instruments will be switched

off to avoid damage. Our gull-design solar

wings help ensure aerodynamic stability.

Þ Today we see dried-up lakes; 3.5 billion years ago, we may have seen something more like this

þ Mariner 9, the frst craft to enter Martian orbit, revealed a slew of Earth-like surface features

>

mars’s atmosphere april 37


seasonal Changes

Giant dust stormsIt is when Mars draws closest to the Sun that the greatest planetary-scale dust storms occur. Mars’s wispy atmosphere is unable to transfer heat effciently, causing regional temperature differences of up to 30°C to drive winds above 100km/h, lifting thin dust that blankets whole regions or the entire planet. Summer dust devils are also common. Any astronaut would feel only a mild breeze, although dust storms might also generate worrying static electric ‘e-felds’.

“What we want to understand are the processes

occurring in the upper atmosphere today. What is

its composition and loss rate? How is this affected

by incoming solar energy rates?”

MAVEN will build on the atmospheric

observations of ESA’s Mars Express, which has

been in orbit around Mars for a decade, sampling

current atmospheric loss rates. The ESA probe

identifed Mars’s unique equatorial aurora, a result

of solar wind particles encountering the magnetised

remnants of the planet’s now-lost magnetic feld.

These cause ultraviolet glows that are sadly invisible

to human eyes.

The missing magnetic feld is the frst suspect in

the murder mystery. It’s a symptom of Mars’s small

stature: only half Earth’s size and only 11 per cent

Mars has terrestrial-style seasons, encouraged by its Earth-like axial tilt. Its highly eccentric (very ‘uncircular’) orbit means its distance from the Sun varies over the course of a 687-day Martian year by some 42 million km

shiftinG ice capsMars’s two polar caps undergo dramatic seasonal shifts. During the darkness of winter atmospheric carbon dioxide freezes out of the air, falling as snow. The effect is greatest when Mars is farthest from the Sun; atmospheric pressure drops by a third. The seasonal southern cap is larger (extending more than halfway to the equator) because the Martian seasons are uneven: the southern winter lasts longer, coinciding with Mars’s aphelion, its maximum distance from the Sun. The southern summer is correspondingly short, but also warmer, with 40 per cent more sunlight. This means much of the south pole’s 1km-thick carbon dioxide layer is vaporised, leaving a 3km-thick pole of water ice behind.

equatorial streaksThe sharp-eyed Mars Reconnaissance Orbiter has spotted surface streaks around equatorial territory. Extending downhill, these dark streaks appear at the warmest time of year, fading as the planet grows cooler, only to return the following summer. Flowing liquid water is the most likely explanation, probably originating from buried permafrost with salt deposits acting as a kind of antifreeze. This 2013 discovery builds on earlier fnds of apparent freshly formed gullies down craters and slopes.

MAVEN’s bird-like ‘gull wings’ will help it swoop low over the Martian surface

>

JUNE

2001

SEptEMbEr

2001



seasonal Changes

Giant dust stormsIt is when Mars draws closest to the Sun that the greatest planetary-scale dust storms occur. Mars’s wispy atmosphere is unable to transfer heat effciently, causing regional temperature differences of up to 30°C to drive winds above 100km/h, lifting thin dust that blankets whole regions or the entire planet. Summer dust devils are also common. Any astronaut would feel only a mild breeze, although dust storms might also generate worrying static electric ‘e-felds’.

“What we want to understand are the processes

occurring in the upper atmosphere today. What is

its composition and loss rate? How is this affected

by incoming solar energy rates?”

MAVEN will build on the atmospheric

observations of ESA’s Mars Express, which has

been in orbit around Mars for a decade, sampling

current atmospheric loss rates. The ESA probe

identifed Mars’s unique equatorial aurora, a result

of solar wind particles encountering the magnetised

remnants of the planet’s now-lost magnetic feld.

These cause ultraviolet glows that are sadly invisible

to human eyes.

The missing magnetic feld is the frst suspect in

the murder mystery. It’s a symptom of Mars’s small

stature: only half Earth’s size and only 11 per cent

Mars has terrestrial-style seasons, encouraged by its Earth-like axial tilt. Its highly eccentric (very ‘uncircular’) orbit means its distance from the Sun varies over the course of a 687-day Martian year by some 42 million km

shiftinG ice capsMars’s two polar caps undergo dramatic seasonal shifts. During the darkness of winter atmospheric carbon dioxide freezes out of the air, falling as snow. The effect is greatest when Mars is farthest from the Sun; atmospheric pressure drops by a third. The seasonal southern cap is larger (extending more than halfway to the equator) because the Martian seasons are uneven: the southern winter lasts longer, coinciding with Mars’s aphelion, its maximum distance from the Sun. The southern summer is correspondingly short, but also warmer, with 40 per cent more sunlight. This means much of the south pole’s 1km-thick carbon dioxide layer is vaporised, leaving a 3km-thick pole of water ice behind.

equatorial streaksThe sharp-eyed Mars Reconnaissance Orbiter has spotted surface streaks around equatorial territory. Extending downhill, these dark streaks appear at the warmest time of year, fading as the planet grows cooler, only to return the following summer. Flowing liquid water is the most likely explanation, probably originating from buried permafrost with salt deposits acting as a kind of antifreeze. This 2013 discovery builds on earlier fnds of apparent freshly formed gullies down craters and slopes.

MAVEN’s bird-like ‘gull wings’ will help it swoop low over the Martian surface

>

JUNE

2001

SEptEMbEr

2001

38


its mass with about 38 per cent terrestrial gravity.

Mars’s smaller molten core would have cooled

rapidly, shutting down its protective magnetic feld.

At high altitude, gases are split apart by ultraviolet

radiation into electrically charged ions, which are

then accelerated to escape velocity by the solar

wind. Like a slow-motion comet, Mars’s atmosphere

is being very gradually blown away. The snag is that

Mars Express suggests that escape susceptibility is

limited to lightweight atoms such as hydrogen or

oxygen ions – not heavier carbon dioxide, which has

always formed most of the atmosphere.

Suspect two is the possibility that early Mars’s

warm wetness sparked its doom. Carbon was

steadily extracted from the atmosphere by damp

silicate rocks to form solid carbonates. Earth is

only saved a similar fate by plate tectonics regularly

recycling the surface to liberate stored carbon back

into the atmosphere– but, again, Mars is too small

for plate tectonics to take hold. The problem here

is that the vast amount of carbonate deposits this

implies has still to be found.

Suspect three is suggested by the planet’s heavily

cratered surface – and the event due to happen this

October. Heading towards us at 56km/s, Comet

C/2013 A1 Siding Spring is projected to pass within

41,300km of Mars. Both MAVEN and Mars Express

will have their orbits altered to shelter them behind

Mars during closest approach – fearing cometary

dust impacts. They will use their high-gain antennas

as shields and angle their solar arrays edge-on.

Such close encounters are rare today, but as late

as 3.8 billion years ago the Solar System remained

a violent neighbourhood. The Martian atmosphere

might have been expelled to space by repeated

impacts, also triggering catastrophic foods by

temporarily melting permafrost.

The methane mysteryHow lively is today’s Martian atmosphere?

Memorably, James Lovelock came up with his

Gaia theory after contrasting Earth’s life-driven

atmosphere with static Mars. But how static is it

really? In 2004 both Mars Express and ground-

based observatories detected short-lived plumes

of methane over various Martian regions. The

discovery remains hugely controversial – on Earth

it takes hundreds of years for photochemistry to

remove methane from the atmosphere. Then last

year NASA’s Curiosity rover failed to detect any

Mars methane whatsoever, although terrestrial

spectrographic monitoring goes on.

“Most of the time we don’t detect anything; it’s

only released spasmodically,” says Michael Mumma

of the Solar System Exploration Division at NASA’s

The hunT for methaneThe methane sensor on India’s Mars Orbiter Mission (MOM) aims to solve a decade-long scientifc mystery. It will be put into action as MOM rises to its farthest distance from Mars, around 80,000km – at this distance MOM will move relatively slowly compared to Mars below, allowing for long-exposure searches for the spectral fngerprints of this colourless, odourless gas.

In 2004, Mars Express and ground-based observatories detected small amounts of methane gas on Mars, averaging 10 parts per billion but rising as high as 30 at times (by comparison, Earth’s atmosphere contains 1,800 parts per billion). It was an exciting discovery because terrestrial

methane originates mainly from biological processes, or else volcanoes. But last year NASA’s Curiosity rover analysed local air samples, failing to fnd any methane at all.

Had the methane never been there at all, or is some unknown phenomenon removing it from the atmosphere at a rate hundreds of times faster than terrestrial methane? Proposed mechanisms include dust storm ‘electric felds’, soil superoxides and methane-eating bacteria. Hopefully, MOM will help fnd the answer; if not, Europe’s ExoMars Trace Gas Orbiter – due for launch in 2016 and possessing parts per trillion sensitivity, should be able to do so.

MEthaNE rElEaSE: NorthErN SUMMEr 2003

Methane concentration (parts per billion)

0 5 10 15 20 25 30

Data published in 2009 revealed localised methane,

possibly from an active source

MOM, launched in November 2013, will look for methane spectrally

NA

SA

/JPL

-CA

LteC

h, N

ASA

/tr

eN

t SC

hiN

dLe

r, iN

diA

SPA

Ce

reS

eA

rC

h o

rg

AN

iSA

tio

N,

NA

SA

/JPL

-CA

LteC

h/C

orN

eLL

UN

iver

Sit

Y, N

ASA

/JPL

/M

SSS,

eSA

–d

. d

UC

ro

S

>

38


its mass with about 38 per cent terrestrial gravity.

Mars’s smaller molten core would have cooled

rapidly, shutting down its protective magnetic feld.

At high altitude, gases are split apart by ultraviolet

radiation into electrically charged ions, which are

then accelerated to escape velocity by the solar

wind. Like a slow-motion comet, Mars’s atmosphere

is being very gradually blown away. The snag is that

Mars Express suggests that escape susceptibility is

limited to lightweight atoms such as hydrogen or

oxygen ions – not heavier carbon dioxide, which has

always formed most of the atmosphere.

Suspect two is the possibility that early Mars’s

warm wetness sparked its doom. Carbon was

steadily extracted from the atmosphere by damp

silicate rocks to form solid carbonates. Earth is

only saved a similar fate by plate tectonics regularly

recycling the surface to liberate stored carbon back

into the atmosphere– but, again, Mars is too small

for plate tectonics to take hold. The problem here

is that the vast amount of carbonate deposits this

implies has still to be found.

Suspect three is suggested by the planet’s heavily

cratered surface – and the event due to happen this

October. Heading towards us at 56km/s, Comet

C/2013 A1 Siding Spring is projected to pass within

41,300km of Mars. Both MAVEN and Mars Express

will have their orbits altered to shelter them behind

Mars during closest approach – fearing cometary

dust impacts. They will use their high-gain antennas

as shields and angle their solar arrays edge-on.

Such close encounters are rare today, but as late

as 3.8 billion years ago the Solar System remained

a violent neighbourhood. The Martian atmosphere

might have been expelled to space by repeated

impacts, also triggering catastrophic foods by

temporarily melting permafrost.

The methane mysteryHow lively is today’s Martian atmosphere?

Memorably, James Lovelock came up with his

Gaia theory after contrasting Earth’s life-driven

atmosphere with static Mars. But how static is it

really? In 2004 both Mars Express and ground-

based observatories detected short-lived plumes

of methane over various Martian regions. The

discovery remains hugely controversial – on Earth

it takes hundreds of years for photochemistry to

remove methane from the atmosphere. Then last

year NASA’s Curiosity rover failed to detect any

Mars methane whatsoever, although terrestrial

spectrographic monitoring goes on.

“Most of the time we don’t detect anything; it’s

only released spasmodically,” says Michael Mumma

of the Solar System Exploration Division at NASA’s

The hunT for methaneThe methane sensor on India’s Mars Orbiter Mission (MOM) aims to solve a decade-long scientifc mystery. It will be put into action as MOM rises to its farthest distance from Mars, around 80,000km – at this distance MOM will move relatively slowly compared to Mars below, allowing for long-exposure searches for the spectral fngerprints of this colourless, odourless gas.

In 2004, Mars Express and ground-based observatories detected small amounts of methane gas on Mars, averaging 10 parts per billion but rising as high as 30 at times (by comparison, Earth’s atmosphere contains 1,800 parts per billion). It was an exciting discovery because terrestrial

methane originates mainly from biological processes, or else volcanoes. But last year NASA’s Curiosity rover analysed local air samples, failing to fnd any methane at all.

Had the methane never been there at all, or is some unknown phenomenon removing it from the atmosphere at a rate hundreds of times faster than terrestrial methane? Proposed mechanisms include dust storm ‘electric felds’, soil superoxides and methane-eating bacteria. Hopefully, MOM will help fnd the answer; if not, Europe’s ExoMars Trace Gas Orbiter – due for launch in 2016 and possessing parts per trillion sensitivity, should be able to do so.

MEthaNE rElEaSE: NorthErN SUMMEr 2003

Methane concentration (parts per billion)

0 5 10 15 20 25 30

Data published in 2009 revealed localised methane,

possibly from an active source

MOM, launched in November 2013, will look for methane spectrally

NA

SA

/JPL

-CA

LteC

h,

NA

SA

/tr

eN

t SC

hiN

dLe

r,

iNd

iA S

PAC

e reS

eA

rC

h o

rg

AN

iSA

tio

N,

NA

SA

/JPL

-CA

LteC

h/C

orN

eLL

UN

iver

Sit

Y, N

ASA

/JPL

/M

SSS,

eSA

–d

. d

UC

ro

S

>



ABOUT THE WRITER

Sean Blair is a science and technology journalist. A former guinness World records researcher, he now edits eSA’s space engineering website.

sporadic plumes compared to past seasonal

averages. And a new ESA mission, the

ExoMars Trace Gas Orbiter, joins the

search in 2016. It will also measure

broader trace gas isotope ratios

to gain insight into the

atmosphere’s past

rates of change.

“This 2016 mission

should give us some pretty

defnitive information,” says

Mumma. “What we don’t have

yet is an additional destruction

mechanism for the methane to be

disappearing, but there’s much we

don’t know about Mars and that’s

why we continue to send spacecraft

there. It’s an exciting time; within a

decade we should have an answer.”

Þ The ExoMars orbiter will look for clues on how fast Mars’s atmosphere has altered over time

water on mars

The number of times mainstream headline writers have hailed the discovery of ‘Water on Mars!’ must be well into double digits by now. We’ve known Martian water once existed since 1969, when Mariner 9 charted drainage channels – apparent evidence of a warm, wet early Mars. The mystery of these features is that they appear quite abruptly in the landscape, rather than by the gradual accumulation of river systems. These might have been comparatively brief-lived phenomena, based on transitory meltwater from geological activity or meteorite impacts.

The 1970s Viking landers recorded early morning water-ice mist and frost – although coatings are only a fraction of a millimetre thick – while their orbital

counterparts confrmed trace levels of atmospheric water vapour. More recently, Mars Express has shown water vapour can be ‘supersaturated’ when Mars is at its coldest,

making it wetter than previously thought (although still with 10,000 times

less water vapour than Earth). Looking at the ground, radar instruments proved

that the Martian poles contain enough water ice to food the entire surface to a depth of 11m and established that subsurface ice extends down to mid- latitudes. This ice has

been seen directly by the Mars Reconnaissance

Orbiter, following asteroid impacts uncovering the

bright-white of water ice, which eventually fades. Mapping has also

demonstrated Mars’s northern lowlands are suffciently fat to have formed a shallow ocean.

NASA’s rovers have gathered in-situ evidence: Opportunity discovered haematite ‘blueberries’

that can only be formed in water, suggesting the equatorial Meridian Planum plain was once hot springs or even an acid-tinged lake. Last year Curiosity went one better, establishing through streambed clay deposits that 3.5 billion years ago Gale Crater housed a lake with water ‘good enough to drink’.

Spare a thought also for the oft-neglected 2008 Mars Phoenix lander. Although it was immobile, its thrusters cleared dust to reveal bright water ice beneath, and apparent liquid droplets were recorded fowing along its landing struts – potentially the historic frst detection of liquid Martian water – kept from freezing by perchlorate salts.

Goddard Space Flight Center. “We have

campaigns at three observatories – ESO’s

Very Large Telescope in Chile, Keck

and NASA’s Infrared Telescope, both

in Hawaii. Adaptive optics provide

high angular resolution no

matter the distance. The real

issue is we require a large

Doppler shift to take the Mars

spectral lines away from

Earth’s lines. So we observe at

times when Mars has a high

line of sight velocity relative to

Earth – in January it was moving

towards Earth at about 17 km/s

– leaving us confdent we’re not

mistaking terrestrial methane.

“We’re also looking for deuterium,

a heavy isotope of water. If subsurface

methane is being released seasonally by

permafrost melting, then ancient water vapour

might escape too. This would possess a much

lower deuterium-water ratio than surface water

subject to atmospheric escape of lighter isotopes.

And water is much easier to detect than methane.”

Mars Express is meanwhile commencing

localised methane searches to try and catch

Þ Haematite ‘blueberries’ could only have formed in water, providing more evidence

Þ Meteorite impacts revealed hidden deposits

of water ice

S



ABOUT THE WRITER

Sean Blair is a science and technology journalist. A former guinness World records researcher, he now edits eSA’s space engineering website.

sporadic plumes compared to past seasonal

averages. And a new ESA mission, the

ExoMars Trace Gas Orbiter, joins the

search in 2016. It will also measure

broader trace gas isotope ratios

to gain insight into the

atmosphere’s past

rates of change.

“This 2016 mission

should give us some pretty

defnitive information,” says

Mumma. “What we don’t have

yet is an additional destruction

mechanism for the methane to be

disappearing, but there’s much we

don’t know about Mars and that’s

why we continue to send spacecraft

there. It’s an exciting time; within a

decade we should have an answer.”

Þ The ExoMars orbiter will look for clues on how fast Mars’s atmosphere has altered over time

water on mars

The number of times mainstream headline writers have hailed the discovery of ‘Water on Mars!’ must be well into double digits by now. We’ve known Martian water once existed since 1969, when Mariner 9 charted drainage channels – apparent evidence of a warm, wet early Mars. The mystery of these features is that they appear quite abruptly in the landscape, rather than by the gradual accumulation of river systems. These might have been comparatively brief-lived phenomena, based on transitory meltwater from geological activity or meteorite impacts.

The 1970s Viking landers recorded early morning water-ice mist and frost – although coatings are only a fraction of a millimetre thick – while their orbital

counterparts confrmed trace levels of atmospheric water vapour. More recently, Mars Express has shown water vapour can be ‘supersaturated’ when Mars is at its coldest,

making it wetter than previously thought (although still with 10,000 times

less water vapour than Earth). Looking at the ground, radar instruments proved

that the Martian poles contain enough water ice to food the entire surface to a depth of 11m and established that subsurface ice extends down to mid- latitudes. This ice has

been seen directly by the Mars Reconnaissance

Orbiter, following asteroid impacts uncovering the

bright-white of water ice, which eventually fades. Mapping has also

demonstrated Mars’s northern lowlands are suffciently fat to have formed a shallow ocean.

NASA’s rovers have gathered in-situ evidence: Opportunity discovered haematite ‘blueberries’

that can only be formed in water, suggesting the equatorial Meridian Planum plain was once hot springs or even an acid-tinged lake. Last year Curiosity went one better, establishing through streambed clay deposits that 3.5 billion years ago Gale Crater housed a lake with water ‘good enough to drink’.

Spare a thought also for the oft-neglected 2008 Mars Phoenix lander. Although it was immobile, its thrusters cleared dust to reveal bright water ice beneath, and apparent liquid droplets were recorded fowing along its landing struts – potentially the historic frst detection of liquid Martian water – kept from freezing by perchlorate salts.

Goddard Space Flight Center. “We have

campaigns at three observatories – ESO’s

Very Large Telescope in Chile, Keck

and NASA’s Infrared Telescope, both

in Hawaii. Adaptive optics provide

high angular resolution no

matter the distance. The real

issue is we require a large

Doppler shift to take the Mars

spectral lines away from

Earth’s lines. So we observe at

times when Mars has a high

line of sight velocity relative to

Earth – in January it was moving

towards Earth at about 17 km/s

– leaving us confdent we’re not

mistaking terrestrial methane.

“We’re also looking for deuterium,

a heavy isotope of water. If subsurface

methane is being released seasonally by

permafrost melting, then ancient water vapour

might escape too. This would possess a much

lower deuterium-water ratio than surface water

subject to atmospheric escape of lighter isotopes.

And water is much easier to detect than methane.”

Mars Express is meanwhile commencing

localised methane searches to try and catch

Þ Haematite ‘blueberries’ could only have formed in water, providing more evidence

Þ Meteorite impacts revealed hidden deposits

of water ice

S

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our European homepage:

The next generation of solar filters and telescopes

H-alpha Telescopes and Filter

Ca-K Filter

White-Light Solar-Prism

Mars is an alluring target because of how Earth-like many of its surface features are

th

ink

sto

ck Martin Lewis presents the ultimate guide to observing the Red Planet, its top sights, plus his imaging tips

Marsat oPPosition

Mars is an alluring target because of how Earth-like many of its surface features are

th

ink

sto

ck Martin Lewis presents the ultimate guide to observing the Red Planet, its top sights, plus his imaging tips

Marsat oPPosition

42


Mars, that most captivating of planets,

visits our evening sky this spring,

reaching opposition in the constellation

of Virgo on 8 April. The Red Planet is

the only world in the Solar System that readily

reveals details of its rocky surface when viewed

from Earth and this, together with a multitude of

seasonal changes, makes it a fascinating planet to

observe. At opposition, when Mars is at its nearest,

it will shine as a ruddy beacon beckoning you to

view, but be warned, the Mars observing season is

relatively short. Once April is over, the planet appears

to shrink noticeably from week to week and by mid-

August it is all but lost, low in the evening twilight.

Around opposition, Mars will shine at mag.

–1.5, making it just as brilliant as the brightest

star in the night sky. The planet’s reddish colour

will be immediately apparent to the naked eye

and even more obvious in binoculars. Even at

opposition, however, it is unlikely you will see

any surface features in binoculars: for that you

will need a telescope.

When you look through the eyepiece of your

telescope what details on Mars might you be able to

see? The answer to this depends on the size of your

telescope and how steady your skies are, but also

on the planet’s apparent size and its height above

your horizon. Due to Mars’s noticeably elliptical

orbit, its size at opposition can vary by nearly a

factor of two. At its closest, Mars can be as large

as 25 arcseconds across, over half the apparent

diameter of the gas giant Jupiter. Unfortunately for

northern hemisphere observers, these very close

Mars oppositions always occur when the planet is

far south in the sky. Frustratingly for us in the

UK, this means that it then never gets particularly

high in our skies. A low altitude means the view

is much more affected by atmospheric turbulence

and this softens the view, blurring fne surface

detail, and stopping us making the most of

these close approaches.

The previous opposition in 2012 was certainly

not a close one. Mars was nearly at aphelion, its

farthest point from the Sun; at best the planet was

only 14 arcseconds across. However, to make up

for its small size, the planet was well north of the

celestial equator. This meant it was quite high in

our skies, helping us to see good surface details.

During this year’s opposition it will be larger, at

15.1 arcseconds across, but this will be offset by

the fact that Mars will be about 15° lower in the

sky with a maximum altitude of only 33°. Despite

this, on nights of steady seeing there should

still be plenty of details to see on the surface

with your telescope.

Scope size mattersThrough a telescope with a 4-inch or smaller

aperture and with high magnifcation, you should

see the reddish disc and the small brilliantly white

Þ Mars’s striking albedo features are easily seen, especially through a large telescope

Mare Cimmerium

Mare Tyrrhenum

Mare Hadriacum

ArabiaEden

Mare Serpentis

Syrtis Major

Syrtis Minor

Sinus Meridiani

Sinus Sabaeus

Aurorae Sinus

Elysium

Utopia

Baltia

Amazonis

Mare Erythraeum

Arcadia

Tharsis

Niliacus Lacus

Solis Lacus

ArgyreEridania

Ausonia

Mare Acidalium

da

mia

n p

ea

ch

, m

arti

n l

ew

is, c

ha

rt

by p

ete

la

wren

ce,

ste

ve m

arsh

N

E

42


Mars, that most captivating of planets,

visits our evening sky this spring,

reaching opposition in the constellation

of Virgo on 8 April. The Red Planet is

the only world in the Solar System that readily

reveals details of its rocky surface when viewed

from Earth and this, together with a multitude of

seasonal changes, makes it a fascinating planet to

observe. At opposition, when Mars is at its nearest,

it will shine as a ruddy beacon beckoning you to

view, but be warned, the Mars observing season is

relatively short. Once April is over, the planet appears

to shrink noticeably from week to week and by mid-

August it is all but lost, low in the evening twilight.

Around opposition, Mars will shine at mag.

–1.5, making it just as brilliant as the brightest

star in the night sky. The planet’s reddish colour

will be immediately apparent to the naked eye

and even more obvious in binoculars. Even at

opposition, however, it is unlikely you will see

any surface features in binoculars: for that you

will need a telescope.

When you look through the eyepiece of your

telescope what details on Mars might you be able to

see? The answer to this depends on the size of your

telescope and how steady your skies are, but also

on the planet’s apparent size and its height above

your horizon. Due to Mars’s noticeably elliptical

orbit, its size at opposition can vary by nearly a

factor of two. At its closest, Mars can be as large

as 25 arcseconds across, over half the apparent

diameter of the gas giant Jupiter. Unfortunately for

northern hemisphere observers, these very close

Mars oppositions always occur when the planet is

far south in the sky. Frustratingly for us in the

UK, this means that it then never gets particularly

high in our skies. A low altitude means the view

is much more affected by atmospheric turbulence

and this softens the view, blurring fne surface

detail, and stopping us making the most of

these close approaches.

The previous opposition in 2012 was certainly

not a close one. Mars was nearly at aphelion, its

farthest point from the Sun; at best the planet was

only 14 arcseconds across. However, to make up

for its small size, the planet was well north of the

celestial equator. This meant it was quite high in

our skies, helping us to see good surface details.

During this year’s opposition it will be larger, at

15.1 arcseconds across, but this will be offset by

the fact that Mars will be about 15° lower in the

sky with a maximum altitude of only 33°. Despite

this, on nights of steady seeing there should

still be plenty of details to see on the surface

with your telescope.

Scope size mattersThrough a telescope with a 4-inch or smaller

aperture and with high magnifcation, you should

see the reddish disc and the small brilliantly white

Þ Mars’s striking albedo features are easily seen, especially through a large telescope

Mare Cimmerium

Mare Tyrrhenum

Mare Hadriacum

ArabiaEden

Mare Serpentis

Syrtis Major

Syrtis Minor

Sinus Meridiani

Sinus Sabaeus

Aurorae Sinus

Elysium

Utopia

Baltia

Amazonis

Mare Erythraeum

Arcadia

Tharsis

Niliacus Lacus

Solis Lacus

ArgyreEridania

Ausonia

Mare Acidalium

da

mia

n p

ea

ch

, m

arti

n l

ew

is,

ch

art

by p

ete

la

wren

ce,

ste

ve m

arsh

N

E

VIRGO

Spica

ArcturusBOÖTES

SERPENSCAPUT

LIBRA

CORVUS

CRATER

OPHIUCHUS

HYDRA

Porrima

1 AprMars

30 Apr

Saturn

SE S

mars at opposition april 43


north polar ice cap, which is tilted towards us at

the moment. You should also see one or two of the

more prominent darker features on the surface such

as the wedge-shaped region known as the Syrtis

Major, or the Mare Acidalium, a large shield-shaped

darker region in the northern hemisphere. These

dark albedo features are generally areas where the

Martian wind has swept away most of the lighter,

reddish, desert dust, revealing the darker rocky

surface underneath. Such features change subtly

from season to season as the dust is moved around

but it is unlikely you will see much sign of these

variations in a small telescope.

Telescopes with 6-inch or larger apertures

can reveal much more detail on the planet,

particularly on nights of very good seeing. This

includes the obvious seasonal effects that stem

from the fact that Mars’s axis is tilted to a similar

degree to Earth’s. Martian seasons are always one

ahead of those on Earth, meaning Mars’s northern

hemisphere is now moving towards mid-summer.

This means that the north polar cap, which is tilted

towards the Sun and Earth, is shrinking. Through

your telescope you may be able to see the shape as

well as the size of the polar cap and possibly detect

a darker band where the snows have retreated

around the pole.

The dark albedo surface features are also better

seen in larger telescopes. Depending on which side

is facing Earth, exotic sounding features like the

Sinus Sebaeus, Utopia and Aurorae Sinus may be

visible. You may also see several other distinctive

areas identifed on the accompanying albedo map,

shown left. A red flter (Wratten number #25),

screwed into the eyepiece or held between your

eye and the eyepiece, may help you pick out the

more diffcult of these albedo features. The flter

will increase the contrast by darkening the features

relative to the redder background. If the seeing

is good don’t be afraid to increase the eyepiece

magnifcation to pull out more detail. The best

thing is to experiment – you’ll know that you’ve

gone too far when the detail starts to blur out

rather than improve.

þ Just like the Moon, Mars is covered in recognisable named surface features

Þ Attaching a Wratten #25 red flter to your eyepiece can help to reveal less-obvious dark albedo features

Pavonis Lacus

Olympus Mons

Scandia

Amazonis

Mare Sirenum

>

Þ Approximate sky orientation for 1, 15 and 30 April at 01:00 BST, 00:00 BST and 23:00 BST respectively

VIRGO

Spica

ArcturusBOÖTES

SERPENSCAPUT

LIBRA

CORVUS

CRATER

OPHIUCHUS

HYDRA

Porrima

1 AprMars

30 Apr

Saturn

SE S



north polar ice cap, which is tilted towards us at

the moment. You should also see one or two of the

more prominent darker features on the surface such

as the wedge-shaped region known as the Syrtis

Major, or the Mare Acidalium, a large shield-shaped

darker region in the northern hemisphere. These

dark albedo features are generally areas where the

Martian wind has swept away most of the lighter,

reddish, desert dust, revealing the darker rocky

surface underneath. Such features change subtly

from season to season as the dust is moved around

but it is unlikely you will see much sign of these

variations in a small telescope.

Telescopes with 6-inch or larger apertures

can reveal much more detail on the planet,

particularly on nights of very good seeing. This

includes the obvious seasonal effects that stem

from the fact that Mars’s axis is tilted to a similar

degree to Earth’s. Martian seasons are always one

ahead of those on Earth, meaning Mars’s northern

hemisphere is now moving towards mid-summer.

This means that the north polar cap, which is tilted

towards the Sun and Earth, is shrinking. Through

your telescope you may be able to see the shape as

well as the size of the polar cap and possibly detect

a darker band where the snows have retreated

around the pole.

The dark albedo surface features are also better

seen in larger telescopes. Depending on which side

is facing Earth, exotic sounding features like the

Sinus Sebaeus, Utopia and Aurorae Sinus may be

visible. You may also see several other distinctive

areas identifed on the accompanying albedo map,

shown left. A red flter (Wratten number #25),

screwed into the eyepiece or held between your

eye and the eyepiece, may help you pick out the

more diffcult of these albedo features. The flter

will increase the contrast by darkening the features

relative to the redder background. If the seeing

is good don’t be afraid to increase the eyepiece

magnifcation to pull out more detail. The best

thing is to experiment – you’ll know that you’ve

gone too far when the detail starts to blur out

rather than improve.

þ Just like the Moon, Mars is covered in recognisable named surface features

Þ Attaching a Wratten #25 red flter to your eyepiece can help to reveal less-obvious dark albedo features

Pavonis Lacus

Olympus Mons

Scandia

Amazonis

Mare Sirenum

>

Þ Approximate sky orientation for 1, 15 and 30 April at 01:00 BST, 00:00 BST and 23:00 BST respectively

44


da

mia

n p

ea

ch

x 3

, m

arti

n l

ew

is x

4, d

av

e h

olt

, ste

ve m

arsh

x 3

Local dust storms are

another Martian feature to

look out for in large scopes.

Strong winds whip up the

surface dust and push it into

Mars’s atmosphere. These

dust storm areas appear

through the telescope as

signifcantly brighter orange-

yellow areas, which change

between one day and the next.

The dust may mask the normal albedo

features in an area and these storms can

sometimes even go global, turning the planet into

an almost featureless orange ball. One or two local

dust events may be seen during this opposition,

but the bigger global dust storms are not likely;

they only really occur in August and September,

when the planet is closer to the Sun and it receives

the extra heat necessary to power these events.

Chasing cloudsMany people are surprised that ice clouds or haze

can sometimes be seen on Mars – you can read more

about the Red Planet’s atmosphere on page 34.

These features are seasonally related and again

flters help improve their contrast. A blue flter

(Wratten number #80A or #38A) is best to use here

as it darkens the red areas compared to the more

bluish clouds. Hazy cloud tends to appear in the

early morning and evening, and so will be seen at

the western or eastern edges of the planet. Blue

hazy clouds also occur around the polar regions, so

examine the entire edge of the planet with and

without the blue flter to see if you can see signs

of these changing atmospheric features.

During the 2012 opposition, an extensive area

of whitish morning cloud was evident in the

low-lying Tharsis region of Mars. This region is

home to several huge volcanoes, and these have

been seen

to poke holes

through the cloud

layer. Imaging with a

high frame rate camera

may be needed to make such

features visible, as they will be small

and this type of imaging allows you to see more on

the planet than you can through visual observing

(see ‘Imaging Mars’, right).

A different type of cloud to the morning and

evening hazes are the so-called orographic clouds,

which form over high regions and are sometimes

seen centred on some of the larger Martian

volcanoes. During the 2005 opposition Olympus

Mons, the highest volcano in the Solar System at

27km, had a persistent orographic cloud around

it that was easily seen as a small white patch.

TOP: In 2005 large orographic white clouds were visible above prominent features on Mars. Here we see Olympus Mons as a clear white dot in the upper right quadrant with the clouds hovering over it. MIDDLE: The 2007 apparition of Mars began with the planet shrouded in a huge dust storm. This meant surface features were diffcult to resolve. The dust storm cleared as the planet reached opposition. BOTTOM: Beautiful wispy white clouds were on show during the 2012 opposition period, particularly over Olympus Mons and the Tharsis volcano region, which are visible across the centre of the planet.

>

44


da

mia

n p

ea

ch

x 3

, m

arti

n l

ew

is x

4,

da

ve h

olt

, ste

ve m

arsh

x 3

Local dust storms are

another Martian feature to

look out for in large scopes.

Strong winds whip up the

surface dust and push it into

Mars’s atmosphere. These

dust storm areas appear

through the telescope as

signifcantly brighter orange-

yellow areas, which change

between one day and the next.

The dust may mask the normal albedo

features in an area and these storms can

sometimes even go global, turning the planet into

an almost featureless orange ball. One or two local

dust events may be seen during this opposition,

but the bigger global dust storms are not likely;

they only really occur in August and September,

when the planet is closer to the Sun and it receives

the extra heat necessary to power these events.

Chasing cloudsMany people are surprised that ice clouds or haze

can sometimes be seen on Mars – you can read more

about the Red Planet’s atmosphere on page 34.

These features are seasonally related and again

flters help improve their contrast. A blue flter

(Wratten number #80A or #38A) is best to use here

as it darkens the red areas compared to the more

bluish clouds. Hazy cloud tends to appear in the

early morning and evening, and so will be seen at

the western or eastern edges of the planet. Blue

hazy clouds also occur around the polar regions, so

examine the entire edge of the planet with and

without the blue flter to see if you can see signs

of these changing atmospheric features.

During the 2012 opposition, an extensive area

of whitish morning cloud was evident in the

low-lying Tharsis region of Mars. This region is

home to several huge volcanoes, and these have

been seen

to poke holes

through the cloud

layer. Imaging with a

high frame rate camera

may be needed to make such

features visible, as they will be small

and this type of imaging allows you to see more on

the planet than you can through visual observing

(see ‘Imaging Mars’, right).

A different type of cloud to the morning and

evening hazes are the so-called orographic clouds,

which form over high regions and are sometimes

seen centred on some of the larger Martian

volcanoes. During the 2005 opposition Olympus

Mons, the highest volcano in the Solar System at

27km, had a persistent orographic cloud around

it that was easily seen as a small white patch.

TOP: In 2005 large orographic white clouds were visible above prominent features on Mars. Here we see Olympus Mons as a clear white dot in the upper right quadrant with the clouds hovering over it. MIDDLE: The 2007 apparition of Mars began with the planet shrouded in a huge dust storm. This meant surface features were diffcult to resolve. The dust storm cleared as the planet reached opposition. BOTTOM: Beautiful wispy white clouds were on show during the 2012 opposition period, particularly over Olympus Mons and the Tharsis volcano region, which are visible across the centre of the planet.

>



tHE four faCEs OF MARSthrough a telescope, look for mars’s prominent features to work out which region you are looking at. these images are from the 2012 apparition with the north pole at the bottom

iMAging mars

The best way to image planets is to record a video through your telescope using a high frame rate planetary camera and a Barlow lens, then processing the resulting movie to create a high-resolution still image. The fnal image uses only the best moments of seeing and disregards the poor ones, and reveals much more surface detail than you could hope to see through the eyepiece of the same scope. For the best images you can even try using an atmospheric dispersion corrector, which reduces the prismatic effect of our atmosphere; an important consideration given Mars’s lower altitude this apparition.

Colour cameras give slightly less detail than their mono counterparts, but they do dramatically speed up and simplify both the imaging process and the follow-up processing needed. Mars is a relatively easy planet to capture; as long as the atmosphere is steady you should be able to get

interesting images through any driven telescope, although larger instruments will be able to show more detail.

Mars’s high surface brightness allows you to increase the image scale. For cameras with the popular pixel size of 5.6μm, try a Barlow lens that gives effective focal ratios of f/25 to f/35, or even up to f/50 on exceptionally steady nights. For cameras with smaller pixel sizes, drop these focal ratio values in proportion to the pixel size. The Red Planet completes one rotation in 24 hours and 37 minutes; so long as you complete your imaging within fve minutes, you will avoid motion blur.

To fnd out how to image Mars with a mono CCD camera, turn to page 64.

If you see signifcant detail on the planet, have a

go at making a sketch of what you see at the eyepiece.

First spend some time looking without committing

anything to paper. This will let you to tune into the

scene allowing details to slowly reveal themselves.

It’s a good idea to prepare some blanks in advance,

so draw 50mm circles on good-quality cartridge

paper before you observe. It’s also worth using good

quality HB, B and perhaps 2B pencils. You could

even use coloured pencils to depict some of the

different hues present if you’re feeling ambitious.

Mars takes 24 hours and 37 minutes to complete

a rotation, so you can take your time sketching

before the face on show changes noticeably. The

1 Syrtis Major (Central longitude: 320º)

This is the classic view of Mars, showing the prominent dark wedge shape of the Syrtis Major with the pipe-like Sinus Sabaeus off to the right.

2 Mare Cimmerium (Central longitude: 198°)

After 11 days, the Mare Cimmerium is on view at the top. On the left, cloud over Olympus Mons shows up as a white patch. The Amazonis desert flls the centre.

3 Eye of Mars (Central longitude: 82°)

Ten days later, Solis Lacus, known as the ‘Eye of Mars’, is seen at the top left and the dark fngers of Aurorae Sinus are seen upper left. The Mare Acidalium is lower left.

4 Mare Acidalium (Central longitude: 23°)

Another seven days on and the large shield-shaped Mare Acidalium sits above the north polar cap, while the Sinus Sabaeus reappears on the left-hand side.

Þ Stacking single frames from a video (left) creates a high-resolution image (right)

Þ With so much observing potential, sketching the Red Planet is a uniquely rewarding challenge

>

Þ A 3x Barlow attached to a high frame

rate planetary imaging camera



tHE four faCEs OF MARSthrough a telescope, look for mars’s prominent features to work out which region you are looking at. these images are from the 2012 apparition with the north pole at the bottom

iMAging mars

The best way to image planets is to record a video through your telescope using a high frame rate planetary camera and a Barlow lens, then processing the resulting movie to create a high-resolution still image. The fnal image uses only the best moments of seeing and disregards the poor ones, and reveals much more surface detail than you could hope to see through the eyepiece of the same scope. For the best images you can even try using an atmospheric dispersion corrector, which reduces the prismatic effect of our atmosphere; an important consideration given Mars’s lower altitude this apparition.

Colour cameras give slightly less detail than their mono counterparts, but they do dramatically speed up and simplify both the imaging process and the follow-up processing needed. Mars is a relatively easy planet to capture; as long as the atmosphere is steady you should be able to get

interesting images through any driven telescope, although larger instruments will be able to show more detail.

Mars’s high surface brightness allows you to increase the image scale. For cameras with the popular pixel size of 5.6μm, try a Barlow lens that gives effective focal ratios of f/25 to f/35, or even up to f/50 on exceptionally steady nights. For cameras with smaller pixel sizes, drop these focal ratio values in proportion to the pixel size. The Red Planet completes one rotation in 24 hours and 37 minutes; so long as you complete your imaging within fve minutes, you will avoid motion blur.

To fnd out how to image Mars with a mono CCD camera, turn to page 64.

If you see signifcant detail on the planet, have a

go at making a sketch of what you see at the eyepiece.

First spend some time looking without committing

anything to paper. This will let you to tune into the

scene allowing details to slowly reveal themselves.

It’s a good idea to prepare some blanks in advance,

so draw 50mm circles on good-quality cartridge

paper before you observe. It’s also worth using good

quality HB, B and perhaps 2B pencils. You could

even use coloured pencils to depict some of the

different hues present if you’re feeling ambitious.

Mars takes 24 hours and 37 minutes to complete

a rotation, so you can take your time sketching

before the face on show changes noticeably. The

1 Syrtis Major (Central longitude: 320º)

This is the classic view of Mars, showing the prominent dark wedge shape of the Syrtis Major with the pipe-like Sinus Sabaeus off to the right.

2 Mare Cimmerium (Central longitude: 198°)

After 11 days, the Mare Cimmerium is on view at the top. On the left, cloud over Olympus Mons shows up as a white patch. The Amazonis desert flls the centre.

3 Eye of Mars (Central longitude: 82°)

Ten days later, Solis Lacus, known as the ‘Eye of Mars’, is seen at the top left and the dark fngers of Aurorae Sinus are seen upper left. The Mare Acidalium is lower left.

4 Mare Acidalium (Central longitude: 23°)

Another seven days on and the large shield-shaped Mare Acidalium sits above the north polar cap, while the Sinus Sabaeus reappears on the left-hand side.

Þ Stacking single frames from a video (left) creates a high-resolution image (right)

Þ With so much observing potential, sketching the Red Planet is a uniquely rewarding challenge

>

Þ A 3x Barlow attached to a high frame

rate planetary imaging camera

46 mars at opposition april


traCking bAckwARdS

ABOUT THE WRITER

martin lewis is a keen astronomer. as a frequent reviewer for our First Light section, he has an in-depth knowledge of observing the planets with all sorts of equipment.

fact that the Martian day is about 40 minutes longer

than ours on Earth means that the planet appears to

rotate slowly backwards as the days pass. This

difference between a Martian day and an Earth day

also means that you need to wait about fve weeks for

the same face to come into view again if you observe

Mars at its highest each evening. A bit of planning is

needed, therefore, if you want to see the whole of

the Martian globe this spring.

Brief opportunityMars will be more than 15 arcseconds across from

5-23 April and in the middle of this period it will

be highest in the sky half an hour after midnight.

By the end of May, however, it will have shrunk to

less than 12 arcseconds across and will be an hour

past its highest position when it gets dark at 10pm.

Mars is a fascinating planet with its albedo features

and multitude of seasonal changes, so make the most

of April and May to see what you can make out on

the surface of this kindred world. If you are able to,

make some record of the planet’s details this time

around. You can then see what changes occur between

now and May 2016, the next time it’ll be at its closest.

AppARent diamEtErAlthough Mars oppositions occur at regular 26-month intervals, the apparent size of the planet at this time can vary widely, from just over 25 arcseconds to

a little less than 14 arcseconds. This is due to Mars’s elliptical orbit, which causes the Mars-to-Earth distance to be as little as 0.37 AU or as much as 0.67 AU.

The planets orbiting the Sun farther than Earth generally track slowly eastwards through the constellations as the months pass. For several weeks either side of opposition, however, they appear to change direction and move westward, before later resuming their eastward track. The period where they seem to move in reverse is called retrograde motion. It occurs because the faster-moving Earth overtakes a more distant planet, making it appear to move

backwards against the stars. You might see a similar effect on the motorway when overtaking a slower moving car – it appears to move backwards against the more distant scenery. During this apparition, Mars moves in a retrograde direction from 27 February to 18 May, from six weeks before opposition to six weeks after opposition, before recommencing its eastwards track towards Libra.

East

WestEast

Mars

Earth

Sun

Þ As Earth overtakes Mars, the Red Planet appears to move backwards against the stars

S

>

VIRGO

Spica

Porrima

1 Jan

1 Feb

1 Mar

1 Apr

1 May 1 Jun

1 Jul

8 Apr(Opposition)

Mars

α

γ

ζ

η

τ

θ

ch

art

by

pete

la

wre

nc

e, il

lust

ra

tio

ns

by s

tev

e m

ars

h

13 Oct 2020 22.4 arcseconds

27 Jul 2018 24.2 arcseconds

22 May 2016 18.4 arcseconds

8 Apr 2014 15.1 arcseconds

3 Mar 2012 13.9 arcseconds

19 Feb 2027 13.8 arcseconds

16 Jan 2025 14.5 arcseconds

8 Dec 2022 17.0 arcseconds

M

ars

Eart

h

Ven

us

Mer

cury

Mars’s path from the beginning of year through to July 2014

46 mars at opposition april


traCking bAckwARdS

ABOUT THE WRITER

martin lewis is a keen astronomer. as a frequent reviewer for our First Light section, he has an in-depth knowledge of observing the planets with all sorts of equipment.

fact that the Martian day is about 40 minutes longer

than ours on Earth means that the planet appears to

rotate slowly backwards as the days pass. This

difference between a Martian day and an Earth day

also means that you need to wait about fve weeks for

the same face to come into view again if you observe

Mars at its highest each evening. A bit of planning is

needed, therefore, if you want to see the whole of

the Martian globe this spring.

Brief opportunityMars will be more than 15 arcseconds across from

5-23 April and in the middle of this period it will

be highest in the sky half an hour after midnight.

By the end of May, however, it will have shrunk to

less than 12 arcseconds across and will be an hour

past its highest position when it gets dark at 10pm.

Mars is a fascinating planet with its albedo features

and multitude of seasonal changes, so make the most

of April and May to see what you can make out on

the surface of this kindred world. If you are able to,

make some record of the planet’s details this time

around. You can then see what changes occur between

now and May 2016, the next time it’ll be at its closest.

AppARent diamEtErAlthough Mars oppositions occur at regular 26-month intervals, the apparent size of the planet at this time can vary widely, from just over 25 arcseconds to

a little less than 14 arcseconds. This is due to Mars’s elliptical orbit, which causes the Mars-to-Earth distance to be as little as 0.37 AU or as much as 0.67 AU.

The planets orbiting the Sun farther than Earth generally track slowly eastwards through the constellations as the months pass. For several weeks either side of opposition, however, they appear to change direction and move westward, before later resuming their eastward track. The period where they seem to move in reverse is called retrograde motion. It occurs because the faster-moving Earth overtakes a more distant planet, making it appear to move

backwards against the stars. You might see a similar effect on the motorway when overtaking a slower moving car – it appears to move backwards against the more distant scenery. During this apparition, Mars moves in a retrograde direction from 27 February to 18 May, from six weeks before opposition to six weeks after opposition, before recommencing its eastwards track towards Libra.

East

WestEast

Mars

Earth

Sun

Þ As Earth overtakes Mars, the Red Planet appears to move backwards against the stars

S

>

VIRGO

Spica

Porrima

1 Jan

1 Feb

1 Mar

1 Apr

1 May 1 Jun

1 Jul

8 Apr(Opposition)

Mars

α

γ

ζ

η

τ

θ

ch

art

by

pete

la

wre

nc

e, il

lust

ra

tio

ns

by s

tev

e m

ars

h

13 Oct 2020 22.4 arcseconds

27 Jul 2018 24.2 arcseconds

22 May 2016 18.4 arcseconds

8 Apr 2014 15.1 arcseconds

3 Mar 2012 13.9 arcseconds

19 Feb 2027 13.8 arcseconds

16 Jan 2025 14.5 arcseconds

8 Dec 2022 17.0 arcseconds

M

ars

Eart

h

Ven

us

Mer

cury

Mars’s path from the beginning of year through to July 2014

www.MORRISPHOTO.co.ukTel: 08454 30 20 30 Helpline: 01608 649224 Unit 9, Worcester Road Ind Est, CHIPPING NORTON. Oxon. OX7 5XW.

Fax: 01608 644555 Email: [email protected] our website, but if you prefer to call in person our showroom is open Mon-Sat 9am-5pm (Tue 9.30-5pm).

Seen a better price - ask us to match or better All prices valid whilst stocks last and include VAT @ current rate. E&OE.

Dedicated Astronomy section now live on www.morrisphoto.co.uk Magnifications (with optics supplied): x36,

x72, x90, x180. Diameter Primary Mirror: 130mm. Telescope Focal Length: 900mm (f/6.92).Telescope Focal Length: 900mm (f/6.92).

EQ2 Equatorial Mount. R.A. Motor Drive (D.C.) with Multi-Speed Handset. Uses T mount to attach your digital or film SLR.Skywatcher Explorer130M

Newtonian Reflector Telescope £see webMORE SKYWATCHER PRODUCTS

Skyhawk 1145P Sync Scan AZ Go-To Computerised Telescope SAVE £15 £254.99Heritage 76 Mini DobsonianTelescope SAVE £36 £43.10Heritage 130P Mini DobsonianTelescope SAVE £31 £128.90Heritage 114P Virtuoso Auto TrackingTelescope SAVE £20 £179.95

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Optical design: reflector. Aperture: 130 mm. Focal length: 650 mm. Focal ratio: 5.Eyepiece 1:20mm. Magnification 1:32.5 x.

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Astromaster Accessory Kit SAVE £33 £47.00Astromaster Motor Drive £49.99Omni 2x Barlow Lens SAVE £10 £41.99Moon Filter £8.55Universal T Adapter £20.95T Camera Ring (Major Brands) Each £12.99

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1400mm compact tube. 150mm (6”) mirror. Basic 6mm eyepiece (233x magnification). Tripod and equatorial mount- Finderscope. Basic 25mm

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The NG Astro Planetarium allows you to view the nightsky in your own room! It will project the nightsky onto your ceiling, actually

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Astronomy Now March 2014

The 15x magnification is ideal as a long range observation or security

binocular. This model is designed to give high clarity, very high power

and a natural, true to life colour due to multi coated lenses. High Resolution BAK4 prisms ensure a brighter image throughout the range of magnifications by maximising light transmission. Efficient use of the light gathered is particularly important at high magnifications where images appear darker.10 x 50 HD Binoculars £59.9715 x 70 HD Binoculars £84.9720 x 80 HD Binoculars £149.97

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The UK’s Telescope & Equipment Specialists

Call 01223 911150 (local rate) for friendly

advice and phone order

Great Service and Best PricesWe ofer a wide range of telescopes and accessories for all your star-gazing needs,

beginners and experts alike, at our best prices – with free shipping (orders over £50 in UK mainland)

Get expert, friendly advice to select the right equipment for your requirements.

01223 911150 | www.astronomycentre.co.uk | [email protected]

We are ofcial dealers for

www.MORRISPHOTO.co.ukTel: 08454 30 20 30 Helpline: 01608 649224 Unit 9, Worcester Road Ind Est, CHIPPING NORTON. Oxon. OX7 5XW.

Fax: 01608 644555 Email: [email protected] our website, but if you prefer to call in person our showroom is open Mon-Sat 9am-5pm (Tue 9.30-5pm).

Seen a better price - ask us to match or better All prices valid whilst stocks last and include VAT @ current rate. E&OE.

Dedicated Astronomy section now live on www.morrisphoto.co.uk Magnifications (with optics supplied): x36,

x72, x90, x180. Diameter Primary Mirror: 130mm. Telescope Focal Length: 900mm (f/6.92).Telescope Focal Length: 900mm (f/6.92).

EQ2 Equatorial Mount. R.A. Motor Drive (D.C.) with Multi-Speed Handset. Uses T mount to attach your digital or film SLR.Skywatcher Explorer130M

Newtonian Reflector Telescope £see webMORE SKYWATCHER PRODUCTS

Skyhawk 1145P Sync Scan AZ Go-To Computerised Telescope SAVE £15 £254.99Heritage 76 Mini DobsonianTelescope SAVE £36 £43.10Heritage 130P Mini DobsonianTelescope SAVE £31 £128.90Heritage 114P Virtuoso Auto TrackingTelescope SAVE £20 £179.95



1.25” Deluxe Barlow Lens X2 (Double Lens) SAVE £7 £28.991.25” Economy Barlow Lens X2 (Single Lens) SAVE £3 £14.991.25” Lunar/Planetary Filter Set SAVE £3 £26.991.25” Tele Extender SAVE £5 £35.00Light Pollution Filters 1.25/2” SAVE £2 £17.99Moon Filter 1.25” SAVE £1.50 £8.50Electronic Shutter Release Cable To Fit Most Camera Models £6.99Prime Focus Camera Adapter SAVE £7 £24.99

SKYWATCHER EXPLORER 130M

Please note we are just outside the town centre on Worcester Road. FREE PARKING is available outside our premises.

MORE SKYWATCHER PRODUCTSUniversal Camera Adapter £29.957.5, 10, 11.5, 17, 20mm ‘SR Series’ Super Plossi Eyepieces (Each) SAVE £3 £21.9932, 40mm ‘SR Series’ Super Plossi Eyepieces (Each) SAVE £3 £31.99Red Dot Finder SAVE £1 £23.99

Optical design: reflector. Aperture: 130 mm. Focal length: 650 mm. Focal ratio: 5.Eyepiece 1:20mm. Magnification 1:32.5 x.

Eyepiece 2: 10mm. Magnification 2: 65 xMount: CG-3 Equatorial. Motor drive: Included. Optical coatings: multi coated.

Weight: 10.89 kg.Astromaster 130EQ MD Telescope SAVE £87 £142.90

MORE CELESTRON PRODUCTSAstromaster 130EQ Telescope SAVE £65 £135.00LCM114 Computerised Telescope SAVE £71 £279.00LCM80 Computerised Telescope SAVE £128 £229.00

Firstscope 76 SAVE £50 £39.95

Firstscope Accessory Kit SAVE £5 £16.97

Astromaster Accessory Kit SAVE £33 £47.00Astromaster Motor Drive £49.99Omni 2x Barlow Lens SAVE £10 £41.99Moon Filter £8.55Universal T Adapter £20.95T Camera Ring (Major Brands) Each £12.99

CELESTRON ASTROMASTER 130EQ MD

FREE UK Mainland P&P orders over £49

1400mm compact tube. 150mm (6”) mirror. Basic 6mm eyepiece (233x magnification). Tripod and equatorial mount- Finderscope. Basic 25mm

eyepiece (56x magnification) with built in erecting lens. Includes the M-2 Visionary

Motor Unit for EQ2 with a hand controller.Mira Ceti 6” 1400mm/150mm

Telescope With M2 Motor Unit £274.95MORE VISIONARY PRODUCTS

Mira Ceti 6” 1400mm/150mmTelescope £224.95

Telesto Full Size Telescope With M1 Motor £154.99

Telesto Full Size Telescope £124.99

Firstview 76mm Telescope £34.99M2 Motor Unit For EQ2 Mount £57.99 M1 Motor Unit For EQ1 Mount £28.99

VISIONARY MIRA CETI 150 M2 MOTOROptical system Reflector. Mirror diameter

130mm. Focal length 650mm. Mount equatorial. Magnification 26x-195x.

Eyepieces K-10/K-25MM. Viewfinder LED.Barlow lens 3x. Moon filter. Star map. Tripod. Astronomy software.Newton 130/650 Telescope With Accessories £179.00

MORE NG PRODUCTS76/350 Compact Telescope SAVE £20 £39.95

NATIONAL GEOGRAPHIC NEWTON 130/650

The NG Astro Planetarium allows you to view the nightsky in your own room! It will project the nightsky onto your ceiling, actually

true to time and day. There are two different star slide discs for variety,

and the two integrated motors keep the projected image in motion. There is also a 2.0 speaker system to connect a digital music player.Planetarium SAVE £19 £69.00

NATIONAL GEOGRAPHIC PLANETARIUM

£5In-Store Voucher When You Spend

Over £49

Why not visit - we are in a beautiful part of the world! Use this voucher to save £5 when you spend over £49 in store. Only one voucher per customer, not available for mail order. Voucher has no monetary

value - not redeemable for cash. Valid till 31st March 2014.

Astronomy Now March 2014

The 15x magnification is ideal as a long range observation or security

binocular. This model is designed to give high clarity, very high power

and a natural, true to life colour due to multi coated lenses. High Resolution BAK4 prisms ensure a brighter image throughout the range of magnifications by maximising light transmission. Efficient use of the light gathered is particularly important at high magnifications where images appear darker.10 x 50 HD Binoculars £59.9715 x 70 HD Binoculars £84.9720 x 80 HD Binoculars £149.97

VISIONARY 15x70 HD BINOCULARS

The UK’s Telescope & Equipment Specialists

Call 01223 911150 (local rate) for friendly

advice and phone order

Great Service and Best PricesWe ofer a wide range of telescopes and accessories for all your star-gazing needs,

beginners and experts alike, at our best prices – with free shipping (orders over £50 in UK mainland)

Get expert, friendly advice to select the right equipment for your requirements.

01223 911150 | www.astronomycentre.co.uk | [email protected]

We are ofcial dealers for


You can learn more about the Universe by taking an

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WHERE TO STUDY THE

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courses available for enrolment all year round

One of the UK’s most popular and longest standing providers of astronomy distance learning courses. Choose from fve separate astronomy courses, suitable for complete beginner right through to frst-year university standard, including GCSE Astronomy. A certifcate is issued for each completed course. You will fnd a complete syllabus for each of the courses available, along with other details about each course, and the necessary enrolment information on our website. There is a ‘Student Feedback’ link where you can view some of the unsolicited comments we have received from past students. We pride ourselves on being accessible and fexible and offer very attractively priced services, of the highest standards, and we work hard to provide you with what you want. Of paramount importance to us is the one-to-one contact students have with their tutor, who is easily accessible even outside of offce hours.

The UCL Certifcate of Higher Education in Astronomy is taught at the UCL campus in Central London.

The two year course of part-time study requires no subject-related A-level. Study is in UCL’s Physics and Astronomy Department, one evening per week from 6 to 9pm. It has a much greater coverage of astronomy than ordinary evening classes and includes regular practical classes at UCL’s superbly equipped Observatory at Mill Hill.

This course is ideal for keen amateur astronomers, teachers and everyone interested in learning more about astronomy.

The certifcate is endorsed by the Royal Astronomical Society.

Details and application form are linked on the web page below.

020 7679 3943 [email protected] www.ucl.ac.uk/phys/admissions/certifcate

UnivERSiTY cOllEgE lOnDOn


You can learn more about the Universe by taking an

astronomy course. There’s a wide variety on offer,

covering all age groups and levels of experience,

to help you take your interest further.

WHERE TO STUDY THE

0161 653 9092 www.planeteartheducation.co.uk

PlanET EaRTH EDUcaTiOn

courses available for enrolment all year round

One of the UK’s most popular and longest standing providers of astronomy distance learning courses. Choose from fve separate astronomy courses, suitable for complete beginner right through to frst-year university standard, including GCSE Astronomy. A certifcate is issued for each completed course. You will fnd a complete syllabus for each of the courses available, along with other details about each course, and the necessary enrolment information on our website. There is a ‘Student Feedback’ link where you can view some of the unsolicited comments we have received from past students. We pride ourselves on being accessible and fexible and offer very attractively priced services, of the highest standards, and we work hard to provide you with what you want. Of paramount importance to us is the one-to-one contact students have with their tutor, who is easily accessible even outside of offce hours.

The UCL Certifcate of Higher Education in Astronomy is taught at the UCL campus in Central London.

The two year course of part-time study requires no subject-related A-level. Study is in UCL’s Physics and Astronomy Department, one evening per week from 6 to 9pm. It has a much greater coverage of astronomy than ordinary evening classes and includes regular practical classes at UCL’s superbly equipped Observatory at Mill Hill.

This course is ideal for keen amateur astronomers, teachers and everyone interested in learning more about astronomy.

The certifcate is endorsed by the Royal Astronomical Society.

Details and application form are linked on the web page below.

020 7679 3943 [email protected] www.ucl.ac.uk/phys/admissions/certifcate

UnivERSiTY cOllEgE lOnDOn


MPhys (4-year) and BSc (3-year) degree programmes including Physics with Astrophysics. The astrophysics options and research project enable you to pursue in-depth knowledge of astrophysics topics. Programmes include hands-on experience using the Department’s suite of optical and radio telescopes. Key teaching and research areas include nuclear astrophysics, fusion and lasers, nanotechnology, computational and theoretical physics.

01904 322241www.york.ac.uk/physics

THE UnivERSiTY Of YORk

Further details are available at:

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msc-astrophysics.

Enquiries:

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Tel: 020 7882 6958

As one of the world’s leading providers of distance learning astronomy study, UCLan offers a range of part-time courses starting from University Certifcates up to Honours Degree level. University Certifcates are single-module awards designed for people with no prior knowledge of the subject. They can be used towards more advanced awards leading to our BSc (Hons) Astronomy. Visit www.studyastronomy.com for more information.

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MPhys (4-year) and BSc (3-year) degree programmes including Physics with Astrophysics. The astrophysics options and research project enable you to pursue in-depth knowledge of astrophysics topics. Programmes include hands-on experience using the Department’s suite of optical and radio telescopes. Key teaching and research areas include nuclear astrophysics, fusion and lasers, nanotechnology, computational and theoretical physics.

01904 322241www.york.ac.uk/physics

THE UnivERSiTY Of YORk

Further details are available at:

astro.qmul.ac.uk/teaching/

msc-astrophysics.

Enquiries:

[email protected]

Tel: 020 7882 6958

As one of the world’s leading providers of distance learning astronomy study, UCLan offers a range of part-time courses starting from University Certifcates up to Honours Degree level. University Certifcates are single-module awards designed for people with no prior knowledge of the subject. They can be used towards more advanced awards leading to our BSc (Hons) Astronomy. Visit www.studyastronomy.com for more information.

UCLan’s BSc (Hons) and MPhys (Hons) Astrophysics, based at our well-appointed and modern campus in Preston, provide essential training in understanding the physical concepts that govern our Universe. Visit www.uclan.ac.uk/courses for more information.

01772 892400 [email protected] www.studyastronomy.com

UnivERSiTY Of cEnTRal lancaSHiRE

pete

la

wre

nc

e

AprilSky Guide

The sky guide APRIL 51


Mars reaches opposition this month. At this time, the planet will appear at its brightest and largest for the current period of observation. Located in the constellation of Virgo, a telescope will reveal tantalising details on this enigmatic world.

Written by Pete Lawrenceas well as writing The Sky Guide, pete can be seen on The Sky at Night on BBc Four. On page 64, he offers advice on how to avoid motion blur when imaging Mars with a mono high frame rate camera.

plusStephen Tonkin’s

BINOCULAR TOUR

Turn to page 62 for six of this month’s best

binocular sights

The

pete

la

wre

nc

e

AprilSky Guide



Mars reaches opposition this month. At this time, the planet will appear at its brightest and largest for the current period of observation. Located in the constellation of Virgo, a telescope will reveal tantalising details on this enigmatic world.

Written by Pete Lawrenceas well as writing The Sky Guide, pete can be seen on The Sky at Night on BBc Four. On page 64, he offers advice on how to avoid motion blur when imaging Mars with a mono high frame rate camera.

plusStephen Tonkin’s

BINOCULAR TOUR

Turn to page 62 for six of this month’s best

binocular sights

The

52

Highlights


pete

la

wre

nc

e x

8

this icon indicates a good photo opportunity

Your guide to the night sky this month

sunday the whirlpool

Galaxy, M51, is virtually overhead at midnight. this is a great opportunity to get better acquainted with this wonderful object.

27

monday

tonight’s full Moon

lies conveniently between Mars and mag. +1.0 Spica (alpha (a) Virginis). the star should stand out despite the Moon’s glare. Orange-hued Mars, shining at mag. –1.5, will be even more obvious above the Moon’s disc.

14Thursday

the bright star 5.5º to the north of the waxing gibbous

Moon (81% lit) is mag. +1.3 regulus (alpha (a) leonis). regulus should be easy to spot, but see if you can also pick out the fainter stars of the Sickle asterism, which extend above regulus in the shape of a backwards question mark.

10

wednesday

the dark Martian

feature known as the Syrtis Major is centrally located on the planet’s disc around midnight. a small telescope can show this V-shaped object well but, as is always the case with Mars, give your eye time to become accustomed to the view.

23

Tuesday

Mars comes to opposition in

Virgo. the planet has an apparent diameter of 15.1 arcseconds and the north polar cap should be fairly obvious through a telescope. around midnight, the dark V-shaped feature known as the Syrtis Major will be coming into view.

8

saTurday

the eta aquariid meteor shower becomes active

from now until 28 May. the peak zenithal hourly rate of this shower is typically 45 meteors per hour. peak activity occurs early next month, on 6 May.

19

saTurday

a lovely sight

awaits early risers: the waning crescent Moon (11% lit) lies close to brilliant Venus in the dawn twilight. look for the pair around 05:00 BSt (04:00 Ut); the Moon will appear to the left of Venus from the UK.

26

Thursday

the almost full Moon (96% lit)

is just 2.5º from Saturn this morning, low in the southwest. Both objects will be visible from around 22:30 BSt (21:30 Ut) on 16 april, with the Moon slowly but surely closing on the planet as dawn breaks.

17

Tuesday

the Moon’s crescent phase and libration make this a good time to view crater Humboldt, pictured. See page 63.

the best periods to take this month’s Deep-sky tour are from tonight until the 7th and from the 24th until the 30th. See page 60.

1

sunday

the waxing

crescent Moon (45% lit) will lie just 6º south of Jupiter this evening. at mag. –2.0 the planet will be obvious above the lunar disc.

6

52

Highlights


pete

la

wre

nc

e x

8

this icon indicates a good photo opportunity

Your guide to the night sky this month

sunday the whirlpool

Galaxy, M51, is virtually overhead at midnight. this is a great opportunity to get better acquainted with this wonderful object.

27

monday

tonight’s full Moon

lies conveniently between Mars and mag. +1.0 Spica (alpha (a) Virginis). the star should stand out despite the Moon’s glare. Orange-hued Mars, shining at mag. –1.5, will be even more obvious above the Moon’s disc.

14Thursday

the bright star 5.5º to the north of the waxing gibbous

Moon (81% lit) is mag. +1.3 regulus (alpha (a) leonis). regulus should be easy to spot, but see if you can also pick out the fainter stars of the Sickle asterism, which extend above regulus in the shape of a backwards question mark.

10

wednesday

the dark Martian

feature known as the Syrtis Major is centrally located on the planet’s disc around midnight. a small telescope can show this V-shaped object well but, as is always the case with Mars, give your eye time to become accustomed to the view.

23

Tuesday

Mars comes to opposition in

Virgo. the planet has an apparent diameter of 15.1 arcseconds and the north polar cap should be fairly obvious through a telescope. around midnight, the dark V-shaped feature known as the Syrtis Major will be coming into view.

8

saTurday

the eta aquariid meteor shower becomes active

from now until 28 May. the peak zenithal hourly rate of this shower is typically 45 meteors per hour. peak activity occurs early next month, on 6 May.

19

saTurday

a lovely sight

awaits early risers: the waning crescent Moon (11% lit) lies close to brilliant Venus in the dawn twilight. look for the pair around 05:00 BSt (04:00 Ut); the Moon will appear to the left of Venus from the UK.

26

Thursday

the almost full Moon (96% lit)

is just 2.5º from Saturn this morning, low in the southwest. Both objects will be visible from around 22:30 BSt (21:30 Ut) on 16 april, with the Moon slowly but surely closing on the planet as dawn breaks.

17

Tuesday

the Moon’s crescent phase and libration make this a good time to view crater Humboldt, pictured. See page 63.

the best periods to take this month’s Deep-sky tour are from tonight until the 7th and from the 24th until the 30th. See page 60.

1

sunday

the waxing

crescent Moon (45% lit) will lie just 6º south of Jupiter this evening. at mag. –2.0 the planet will be obvious above the lunar disc.

6



HoW To TeLL WHaT equiPmenT you’LL need

Getting started in astronomyIf you’re new to astronomy, you’ll find two essential reads on our website. Visit http://bit.ly/10_lessons for our 10-step guide to getting started and http://bit.ly/First_tel for advice on choosing your first scope.

naKed eyeAllow 20 minutes for your eyes to become dark-adapted

BinoCuLaRS10x50 recommended

SmaLL/medium SCoPeReflector/SCT under 6 inches, refractor under 4 inches

LaRGe SCoPeReflector/SCT over 6 inches, refractor over 4 inches

PHoTo oPPoRTuniTyUse a CCD, planetary camera or standard DSLR

need to knowThe terms and symbols used in The Sky Guide

univeRSaL Time (uT) and BRiTiSH SummeR Time (BST)Universal Time (UT) is the standard time used by astronomers around the world. British Summer Time (BST) is one hour ahead of UT.

Ra (RiGHT aSCenSion) and deC. (deCLinaTion) These coordinates are the night sky’s equivalent of longitude and latitude, describing where an object lies on the celestial ‘globe’.

Pete Lawrence “This month’s highlight has to be the planet Mars and I intend to catch it at every opportunity. I can’t wait to get outside and take some images of

this amazing planet.”

Chris Bramley “There are two sights I want to catch this month. The frst is the Syrtis Major on Mars; I'll also have a sunlounger and sleeping bag at the ready on the 22nd,

when the April Lyrid meteor shower peaks.”

Paul money “I’ll be tracking and photographing the motion of Ceres and Vesta as they come to opposition this month in Virgo, not far from Mars.”

what the team will be observing in april

wednesday

the familiar plough asterism

is virtually overhead around midnight. as the Moon is not around, this is a great time to investigate some of the deep-sky objects on offer in this area, such as the Owl nebula, shown right, and the lovely galaxy pair M81 and M82.

2

Tuesday

Dwarf planet ceres and

minor planet Vesta both come to opposition in Virgo. See page 54.

You may be able to see the start of the penumbral phase of a total lunar eclipse as the Moon sets at 06:00 BSt (05:00 Ut). See page 55.

15

Tuesday

tonight is the peak

of the annual lyrid meteor shower, which is active from 16-26 april. the normal peak zenithal hourly rate for this shower is 10 meteors per hour, but infrequent outbursts have been recorded. See page 55.

22monday

the enigmatically named realm of Galaxies is

due south at 23:30 BSt (22:30 Ut). located within the asterism known as the Bowl of Virgo, this area of the sky is rich in faint galaxies, many of which can be seen with a small telescope.

21

wednesday Keep an eye out

for a slender and rather beautiful waning crescent Moon just after sunset. Once the Sun has dipped below the horizon, keep an eye out for mag. –1.7 Mercury very low down in the west-northwest.

30

Thursday

the waxing crescent Moon

(18% lit) lies close to the Hyades open cluster in taurus this evening. look out for them around 21:30 BSt (20:30 Ut). the Moon should also be showing earthshine, which causes its dark portion to become dimly visible.

3



HoW To TeLL WHaT equiPmenT you’LL need

Getting started in astronomyIf you’re new to astronomy, you’ll find two essential reads on our website. Visit http://bit.ly/10_lessons for our 10-step guide to getting started and http://bit.ly/First_tel for advice on choosing your first scope.

naKed eyeAllow 20 minutes for your eyes to become dark-adapted

BinoCuLaRS10x50 recommended

SmaLL/medium SCoPeReflector/SCT under 6 inches, refractor under 4 inches

LaRGe SCoPeReflector/SCT over 6 inches, refractor over 4 inches

PHoTo oPPoRTuniTyUse a CCD, planetary camera or standard DSLR

need to knowThe terms and symbols used in The Sky Guide

univeRSaL Time (uT) and BRiTiSH SummeR Time (BST)Universal Time (UT) is the standard time used by astronomers around the world. British Summer Time (BST) is one hour ahead of UT.

Ra (RiGHT aSCenSion) and deC. (deCLinaTion) These coordinates are the night sky’s equivalent of longitude and latitude, describing where an object lies on the celestial ‘globe’.

Pete Lawrence “This month’s highlight has to be the planet Mars and I intend to catch it at every opportunity. I can’t wait to get outside and take some images of

this amazing planet.”

Chris Bramley “There are two sights I want to catch this month. The frst is the Syrtis Major on Mars; I'll also have a sunlounger and sleeping bag at the ready on the 22nd,

when the April Lyrid meteor shower peaks.”

Paul money “I’ll be tracking and photographing the motion of Ceres and Vesta as they come to opposition this month in Virgo, not far from Mars.”

what the team will be observing in april

wednesday

the familiar plough asterism

is virtually overhead around midnight. as the Moon is not around, this is a great time to investigate some of the deep-sky objects on offer in this area, such as the Owl nebula, shown right, and the lovely galaxy pair M81 and M82.

2

Tuesday

Dwarf planet ceres and

minor planet Vesta both come to opposition in Virgo. See page 54.

You may be able to see the start of the penumbral phase of a total lunar eclipse as the Moon sets at 06:00 BSt (05:00 Ut). See page 55.

15

Tuesday

tonight is the peak

of the annual lyrid meteor shower, which is active from 16-26 april. the normal peak zenithal hourly rate for this shower is 10 meteors per hour, but infrequent outbursts have been recorded. See page 55.

22monday

the enigmatically named realm of Galaxies is

due south at 23:30 BSt (22:30 Ut). located within the asterism known as the Bowl of Virgo, this area of the sky is rich in faint galaxies, many of which can be seen with a small telescope.

21

wednesday Keep an eye out

for a slender and rather beautiful waning crescent Moon just after sunset. Once the Sun has dipped below the horizon, keep an eye out for mag. –1.7 Mercury very low down in the west-northwest.

30

Thursday

the waxing crescent Moon

(18% lit) lies close to the Hyades open cluster in taurus this evening. look out for them around 21:30 BSt (20:30 Ut). the Moon should also be showing earthshine, which causes its dark portion to become dimly visible.

3

54


3 top sightsCeres and Vesta at opposition

NASA’S DAwN miSSioN is

approaching its second phase,

with the spacecraft getting ever

closer to dwarf planet Ceres.

Both Ceres and minor planet

Vesta – Dawn’s previous stop

– are in the same part of the sky

and enter opposition on the 15th.

Ceres was once the king of

the minor planets. with a

diameter of just under 1,000km,

it’s a body massive enough for

gravity to mould its shape into a

sphere. Ultimately this led to

Ceres being promoted from

minor planet to dwarf planet

back in 2006, at the same time

the international Astronomical

Union refned the defnitions of

what makes a planet ‘a planet’.

Dawn is due to reach Ceres

in spring 2015, so we should

know a lot more about this

amazing world next year.

Ceres starts the month at

mag. +7.1, making it an easy

binocular target. it brightens

by a tiny amount to mag. +7.0

around opposition on 15 April,

before dropping back to mag.

+7.1 again by the end of the

month. Throughout April it

moves from just north of mag.

+4.2 Tau (t) Virginis to a

position between mag. +5.4

84 Virginis and ffth-magnitude

variable star 78 Virginis.

Nearby is Vesta, a body with

a mean diameter just half that

of Ceres and classifed as a

minor planet. Despite being

smaller than Ceres, Vesta is

brighter; in fact the brightest of

all the minor planets. During

April its magnitude starts at

mag. +5.9, increases to mag.

+5.8 around opposition before

falling back to mag. +5.9 again.

This places Vesta just within

the bounds of naked-eye

visibility under dark skies. Like

Ceres, Vesta is also in Virgo

and appears to be travelling

along the same part of the sky.

At the start of the month, it

can be found just to the west of

Tau Virginis. it then heads on a

similar path to Ceres towards

78 Virginis, which it lies close

to by the end of April.

if you have clear skies and

a DSLR, these close encounters

will give you a great opportunity

to record the journeys. A 100mm

lens will produce an image

frame 12º across. Centre on

84 Virginis and take as many

shots as you can over the

course of the month. Load them

into a layer-based image editor

such as Photoshop or GimP as

separate layers, then align

common stars between frames.

Finally, set the blend mode of

all images, except the lowest

one, to ‘Lighten’. This should

reveal the passage of Ceres and

Vesta across the night sky.

pete

la

wre

nc

e x 4

WHen: all month

Ceres and vesta both pass 84 virginis during april, the star acting as a reference point to their progress

c

b

tCU

e

78

84

92

1 Apr

1 Apr11 Apr

11 Apr

21 Apr

21 Apr

1 May 1 May

Ceres

Vesta

1 Apr

15 AprMars

VIRGO

Heze

Auva

need To know!an object’s brightness is

given by its magnitude. the lower the number, the brighter the object: with the naked eye you can see down to mag. +6.0. at mag. +5.9 for much of the month, vesta is near naked-eye visibility

don’T

miss…

54


3 top sightsCeres and Vesta at opposition

NASA’S DAwN miSSioN is

approaching its second phase,

with the spacecraft getting ever

closer to dwarf planet Ceres.

Both Ceres and minor planet

Vesta – Dawn’s previous stop

– are in the same part of the sky

and enter opposition on the 15th.

Ceres was once the king of

the minor planets. with a

diameter of just under 1,000km,

it’s a body massive enough for

gravity to mould its shape into a

sphere. Ultimately this led to

Ceres being promoted from

minor planet to dwarf planet

back in 2006, at the same time

the international Astronomical

Union refned the defnitions of

what makes a planet ‘a planet’.

Dawn is due to reach Ceres

in spring 2015, so we should

know a lot more about this

amazing world next year.

Ceres starts the month at

mag. +7.1, making it an easy

binocular target. it brightens

by a tiny amount to mag. +7.0

around opposition on 15 April,

before dropping back to mag.

+7.1 again by the end of the

month. Throughout April it

moves from just north of mag.

+4.2 Tau (t) Virginis to a

position between mag. +5.4

84 Virginis and ffth-magnitude

variable star 78 Virginis.

Nearby is Vesta, a body with

a mean diameter just half that

of Ceres and classifed as a

minor planet. Despite being

smaller than Ceres, Vesta is

brighter; in fact the brightest of

all the minor planets. During

April its magnitude starts at

mag. +5.9, increases to mag.

+5.8 around opposition before

falling back to mag. +5.9 again.

This places Vesta just within

the bounds of naked-eye

visibility under dark skies. Like

Ceres, Vesta is also in Virgo

and appears to be travelling

along the same part of the sky.

At the start of the month, it

can be found just to the west of

Tau Virginis. it then heads on a

similar path to Ceres towards

78 Virginis, which it lies close

to by the end of April.

if you have clear skies and

a DSLR, these close encounters

will give you a great opportunity

to record the journeys. A 100mm

lens will produce an image

frame 12º across. Centre on

84 Virginis and take as many

shots as you can over the

course of the month. Load them

into a layer-based image editor

such as Photoshop or GimP as

separate layers, then align

common stars between frames.

Finally, set the blend mode of

all images, except the lowest

one, to ‘Lighten’. This should

reveal the passage of Ceres and

Vesta across the night sky.

pete

la

wre

nc

e x 4

WHen: all month

Ceres and vesta both pass 84 virginis during april, the star acting as a reference point to their progress

c

b

tCU

e

78

84

92

1 Apr

1 Apr11 Apr

11 Apr

21 Apr

21 Apr

1 May 1 May

Ceres

Vesta

1 Apr

15 AprMars

VIRGO

Heze

Auva

need To know!an object’s brightness is

given by its magnitude. the lower the number, the brighter the object: with the naked eye you can see down to mag. +6.0. at mag. +5.9 for much of the month, vesta is near naked-eye visibility

don’T

miss…



The April lyrids are one

of the regular annual meteor

showers and a welcome break

from the relatively sparse period

of meteor activity that occurs

at the start of the year. The

shower is active from 16-26

April, peaking on the 22nd.

The Moon is going to

interfere at the start of this

period, being fractionally past

full on the night of the 16th,

rising at 21:50 BsT (20:50 UT).

however, over the next few days

the Moon’s decrease in phase,

coupled with it slipping

farther to the south and east

in the sky, will aid meteor

visibility. The Moon is absent

from the evening sky on the

22nd; it rises at around 03:15

BsT (02:15 UT) on the 23rd,

when it will show a waning

crescent (41% lit) phase.

The April lyrids typically

show a peak of around 10

meteors per hour. This is the

zenithal hourly rate – the

value that indicates the

number of meteors you’d see

if the shower radiant, where

the meteors appear to emanate

from, were directly overhead.

The zenithal hourly rate

fgure is only a guide, however,

as it assumes perfect skies and

the fact that you can see the

entire sky in one go – which

unfortunately you can’t!

Consequently, the visually

observed rate will be lower.

The April lyrids are a result

of earth passing through the

dust stream spread along the

orbit of comet C/1861 G1

Thatcher. its meteors appear

to emanate from a location

slightly off to the west of mag.

0.0 Vega (Alpha (a) lyrae),

with an average trail

brightness of mag. +2.0.

Outbursts from the April

A ToTAL LUNAR eclipse

takes place on 15 April.

Unfortunately the main part

occurs after the moon has set

for observers in the UK, but

you may be able to catch the

beginning of the event.

The main, dark part of the

shadow, known as the umbra,

begins to cross the lunar disc

at 06:58 BST (05:58 UT), by

which point the moon will be

no longer visible from the UK.

But we should be able to see

the fainter, outer part of

Earth’s shadow, known as the

penumbra, begin to encroach

on the lunar disc.

The penumbra frst starts

to cross the edge of the moon

at 05:53 BST (04:53 UT), when

the moon is still 2º above the

UK’s west-southwest horizon.

whether we get to see any

hint of shading from the

penumbral part of the eclipse

can’t be predicted with

certainty, but it’s always worth

going out to have a look.

Locate the full moon at

05:30 BST (04:30 UT) and you

should see bright mars off to

the right and fainter, mag.

+1.0 Spica (Alpha (a)

Virginis), just 1º from the

moon’s centre, off to the lower

left. As the moon gets closer

to the horizon it will be nicely

located in the Belt of Venus

– the projection of the closer

part of Earth’s shadow in the

atmosphere.

lyrids occur roughly every 60

years, with 700 meteors per hour

recorded in 1803. sadly, the

last one was in 1982, so we’re

not expecting to see anything

out of the ordinary this time.

The shower radiant lies between the Summer Triangle and Keystone asterisms

Summer Triangle

CYGNUS

Deneb

Vega

Altair

Keystone

LYRA

VULPECULA

SAGITTA

AQUILA

DELPHINUS

HERCULES

April LyridsRadiant

15 Apr

25 Apr

20 Apr

22 Apr

Total lunar eclipse

The orionids peak on 21 october, but you’ll have to

contend with a bright moon

need To know!the planets of the Solar

System occupy similar orbital planes; it is this ‘co-planar’ nature that allows us to see conjunctions from our perspective on earth.

mag. +1.0 Spica sits below and left of the moon as the eclipse begins

WHen: From 05:30 BST (04:30 uT) on 15 april

April Lyrid meteor shower WHen: 16-26 april; peak occurs on the 22nd



The April lyrids are one

of the regular annual meteor

showers and a welcome break

from the relatively sparse period

of meteor activity that occurs

at the start of the year. The

shower is active from 16-26

April, peaking on the 22nd.

The Moon is going to

interfere at the start of this

period, being fractionally past

full on the night of the 16th,

rising at 21:50 BsT (20:50 UT).

however, over the next few days

the Moon’s decrease in phase,

coupled with it slipping

farther to the south and east

in the sky, will aid meteor

visibility. The Moon is absent

from the evening sky on the

22nd; it rises at around 03:15

BsT (02:15 UT) on the 23rd,

when it will show a waning

crescent (41% lit) phase.

The April lyrids typically

show a peak of around 10

meteors per hour. This is the

zenithal hourly rate – the

value that indicates the

number of meteors you’d see

if the shower radiant, where

the meteors appear to emanate

from, were directly overhead.

The zenithal hourly rate

fgure is only a guide, however,

as it assumes perfect skies and

the fact that you can see the

entire sky in one go – which

unfortunately you can’t!

Consequently, the visually

observed rate will be lower.

The April lyrids are a result

of earth passing through the

dust stream spread along the

orbit of comet C/1861 G1

Thatcher. its meteors appear

to emanate from a location

slightly off to the west of mag.

0.0 Vega (Alpha (a) lyrae),

with an average trail

brightness of mag. +2.0.

Outbursts from the April

A ToTAL LUNAR eclipse

takes place on 15 April.

Unfortunately the main part

occurs after the moon has set

for observers in the UK, but

you may be able to catch the

beginning of the event.

The main, dark part of the

shadow, known as the umbra,

begins to cross the lunar disc

at 06:58 BST (05:58 UT), by

which point the moon will be

no longer visible from the UK.

But we should be able to see

the fainter, outer part of

Earth’s shadow, known as the

penumbra, begin to encroach

on the lunar disc.

The penumbra frst starts

to cross the edge of the moon

at 05:53 BST (04:53 UT), when

the moon is still 2º above the

UK’s west-southwest horizon.

whether we get to see any

hint of shading from the

penumbral part of the eclipse

can’t be predicted with

certainty, but it’s always worth

going out to have a look.

Locate the full moon at

05:30 BST (04:30 UT) and you

should see bright mars off to

the right and fainter, mag.

+1.0 Spica (Alpha (a)

Virginis), just 1º from the

moon’s centre, off to the lower

left. As the moon gets closer

to the horizon it will be nicely

located in the Belt of Venus

– the projection of the closer

part of Earth’s shadow in the

atmosphere.

lyrids occur roughly every 60

years, with 700 meteors per hour

recorded in 1803. sadly, the

last one was in 1982, so we’re

not expecting to see anything

out of the ordinary this time.

The shower radiant lies between the Summer Triangle and Keystone asterisms

Summer Triangle

CYGNUS

Deneb

Vega

Altair

Keystone

LYRA

VULPECULA

SAGITTA

AQUILA

DELPHINUS

HERCULES

April LyridsRadiant

15 Apr

25 Apr

20 Apr

22 Apr

Total lunar eclipse

The orionids peak on 21 october, but you’ll have to

contend with a bright moon

need To know!the planets of the Solar

System occupy similar orbital planes; it is this ‘co-planar’ nature that allows us to see conjunctions from our perspective on earth.

mag. +1.0 Spica sits below and left of the moon as the eclipse begins

WHen: From 05:30 BST (04:30 uT) on 15 april

April Lyrid meteor shower WHen: 16-26 april; peak occurs on the 22nd

BOÖTESArcturus

VIRGO

CORVUS

Spica

Porrima

Heze

Vindemiatrix

Zavijava

LEO

Mars30th

1st

`

¡

`

g

a

a

b

d

c

56


mARS REAChES oPPoSiTioN on

8 April and is visible all night long. on

this date the planet will be in the opposite

part of the sky to the Sun and appear

at its brightest for the current

period of observation

at mag. –1.5.

At the start of

the month mars

appears to be 14.7

arcseconds across

when viewed

through a

telescope. At this

scale, a small scope

should be capable of

revealing the main

markings on the planet,

such as the V-shaped Syrtis

major. The ‘V’ description only

really works in an inverted

telescopic view as the tip of the

The phase, tilt and relative sizes of the planets in April. Each planet is shown with south at the top, to show what it looks like through a telescope

How the planets will appear this month

maRS 15 apr

JuPiTeR 15 apr

SaTuRn 15 apr

uRanuS 15 apr

noT viSiBLe

aRCSeCondS

0” 10” 20” 30” 40” 50” 1’

pete l

aw

ren

ce x

2

The planets

‘V’ points north. we’ve indicated a

couple of times to look out for

the Syrtis major in this

month’s highlights

calendar on pages

52-53. it is just one

of several features

that appear dark

against mars’s

lighter deserts.

Roughly four

and a half hours

after the Syrtis major

is on the centreline of

the planet’s disc, a

smaller two-pronged feature

comes into view; one of the

prongs is known as the Sinus

meridiani. This feature marks

the martian equivalent of the Greenwich

meridian on the martian globe. Another

(this time bright) feature that should be

fairly easy to spot with a small telescope is

the planet’s north polar cap.

mars continues to get closer to Earth

and so appear larger through a telescope

for about a week following opposition. on

the 15th the planet achieves an apparent

diameter of 15.2 arcseconds. Though this

is not much more than that shown on the

8th, where mars is concerned every little

bit is most welcome.

At the end of the month, mars is mag.

–1.2, has an apparent diameter of 14.6

arcseconds and sits 1.5º from mag. +3.4

Porrima (Gamma (g) Virginis). For more

tips on observing mars at opposition, turn

to our in-depth feature on page 41.

MARs

BeST Time in aPRiL: 8 April, 01:22 BST (00:22 UT) aLTiTude: 31º LoCaTion: Virgo

diReCTion: SouthReCommended equiPmenT: 6-inch or larger telescopeFeaTuReS oF inTeReST: Polar caps, dark markings, clouds and dust storms.

venuS 15 apr

meRCuRy 15 apr

mars stays in virgo throughout april; it won’t be hard to find, blazing away at a brilliant mag. –1.5

meRCuRy 1 apr

mars’s north polar cap should be an easy spot

nePTune 15 apr

noT viSiBLe

Pick of The monTh

meRCuRy 30 apr

BOÖTESArcturus

VIRGO

CORVUS

Spica

Porrima

Heze

Vindemiatrix

Zavijava

LEO

Mars30th

1st

`

¡

`

g

a

a

b

d

c

56


mARS REAChES oPPoSiTioN on

8 April and is visible all night long. on

this date the planet will be in the opposite

part of the sky to the Sun and appear

at its brightest for the current

period of observation

at mag. –1.5.

At the start of

the month mars

appears to be 14.7

arcseconds across

when viewed

through a

telescope. At this

scale, a small scope

should be capable of

revealing the main

markings on the planet,

such as the V-shaped Syrtis

major. The ‘V’ description only

really works in an inverted

telescopic view as the tip of the

The phase, tilt and relative sizes of the planets in April. Each planet is shown with south at the top, to show what it looks like through a telescope

How the planets will appear this month

maRS 15 apr

JuPiTeR 15 apr

SaTuRn 15 apr

uRanuS 15 apr

noT viSiBLe

aRCSeCondS

0” 10” 20” 30” 40” 50” 1’

pete l

aw

ren

ce x

2

The planets

‘V’ points north. we’ve indicated a

couple of times to look out for

the Syrtis major in this

month’s highlights

calendar on pages

52-53. it is just one

of several features

that appear dark

against mars’s

lighter deserts.

Roughly four

and a half hours

after the Syrtis major

is on the centreline of

the planet’s disc, a

smaller two-pronged feature

comes into view; one of the

prongs is known as the Sinus

meridiani. This feature marks

the martian equivalent of the Greenwich

meridian on the martian globe. Another

(this time bright) feature that should be

fairly easy to spot with a small telescope is

the planet’s north polar cap.

mars continues to get closer to Earth

and so appear larger through a telescope

for about a week following opposition. on

the 15th the planet achieves an apparent

diameter of 15.2 arcseconds. Though this

is not much more than that shown on the

8th, where mars is concerned every little

bit is most welcome.

At the end of the month, mars is mag.

–1.2, has an apparent diameter of 14.6

arcseconds and sits 1.5º from mag. +3.4

Porrima (Gamma (g) Virginis). For more

tips on observing mars at opposition, turn

to our in-depth feature on page 41.

MARs

BeST Time in aPRiL: 8 April, 01:22 BST (00:22 UT) aLTiTude: 31º LoCaTion: Virgo

diReCTion: SouthReCommended equiPmenT: 6-inch or larger telescopeFeaTuReS oF inTeReST: Polar caps, dark markings, clouds and dust storms.

venuS 15 apr

meRCuRy 15 apr

mars stays in virgo throughout april; it won’t be hard to find, blazing away at a brilliant mag. –1.5

meRCuRy 1 apr

mars’s north polar cap should be an easy spot

nePTune 15 apr

noT viSiBLe

Pick of The monTh

meRCuRy 30 apr

MeRCURy BeST Time in aPRiL: 30 April, 21:00 BST (20:00 UT) aLTiTude: 1º (low)LoCaTion: AriesdiReCTion: West-northwestmercury spends most of the

month poorly placed in the

morning sky, with both planet

and Sun rising at approximately

the same time. Superior

conjunction occurs on the 26th

and the prospects for spotting

mercury in the evening sky are

much better. See if you can catch

a glimpse of the mag. –1.7

planet very low on the west-

northwest horizon shortly after

sunset at the end of the month.

VeNUs BeST Time in aPRiL: 25 and 26 April, 05:20 BST (04:20 UT)aLTiTude: 5º (low)LoCaTion: AquariusdiReCTion: EastVenus is a morning object that

shines brighter than mag. –4.0

all month. Despite this, the

planet’s aspect as seen from

the UK is worsening; it’s quite

low in the dawn twilight prior

to sunrise. A telescope will

now show its disc to have a

gibbous phase. At the start

of April, Venus appears to be

22 arcseconds across with a

phase of 54%. By month end,

this will have changed to

17 arcseconds and a phase of

66%. Look out for attractive

conjunctions between Venus

and the waning crescent moon

in the east-southeast dawn sky

on the 25th and 26th.

JUpITeR BeST Time in aPRiL: 1 April, 21:30 BST (20:30 UT)aLTiTude: 52º LoCaTion: GeminidiReCTion: SouthwestJupiter is best seen at the start

of April, when its impressive

mag. –1.2 dot can be seen 52º

up in the southwest as the

sky darkens. At the start of

April the planet shows a

38-arcsecond disc when

viewed through a telescope,

plenty big enough to show

some great detail even with

small instruments. on the

6th, the waxing crescent

moon (45% lit) lies 6º below

the planet. By the end of the

month, the distance between

us and Jupiter will have

increased, resulting in the

planet appearing slightly

smaller at 35 arcseconds

across, and slightly fainter at

mag. –1.9. The planet remains

in Gemini all month.

sATURN BeST Time in aPRiL: 30 April, 02:00 BST (01:00 UT) aLTiTude: 21º LoCaTion: LibradiReCTion: SouthSitting in the constellation

of Libra, Saturn doesn’t get

very high above the UK’s

southern horizon, even when

due south. Don’t let that deter

you though. if you have a

telescope, it’s defnitely worth

trying to get a view of this

beautiful planet.

At the start of April, Saturn

is mag. +0.6 and its disc

appears to be 18 arcseconds

across. it rises at 22:30 BST

(21:30 UT) on the 1st and

manages to reach its highest

point in the sky, 21º up and

due south, in darkness. The

almost full moon lies just

2º from Saturn in the early

hours of 17 April. Look out

for the pair low in the

southwest at around 05:30

BST (04:30 UT). At the end

of the month, Saturn is

visible all night long and

this is the best time to try

and get a view of it.

NOT VISIBLE THIS MONTHURANUs, NepTUNe

AprilUsing a small scope you’ll be able to spot Saturn’s biggest moons. their positions change dramatically during the month, as shown on the diagram. the line by each date on the left represents midnight.

SaT u R n ’S m o o nS

arcminutes

DATE WEST EAST

3210123

2

1

3

5

4

6

8

7

9

11

10

12

14

13

15

17

16

18

20

19

21

23

22

24

25

26

28

27

29

30

1

Dione Rhea TitanTethys Iapetus Saturn

See what the planets look like through your telescope with the feld of view calculator on our website at:

http://www.skyatnightmagazine.com/astronomy-tools

MeRCURy BeST Time in aPRiL: 30 April, 21:00 BST (20:00 UT) aLTiTude: 1º (low)LoCaTion: AriesdiReCTion: West-northwestmercury spends most of the

month poorly placed in the

morning sky, with both planet

and Sun rising at approximately

the same time. Superior

conjunction occurs on the 26th

and the prospects for spotting

mercury in the evening sky are

much better. See if you can catch

a glimpse of the mag. –1.7

planet very low on the west-

northwest horizon shortly after

sunset at the end of the month.

VeNUs BeST Time in aPRiL: 25 and 26 April, 05:20 BST (04:20 UT)aLTiTude: 5º (low)LoCaTion: AquariusdiReCTion: EastVenus is a morning object that

shines brighter than mag. –4.0

all month. Despite this, the

planet’s aspect as seen from

the UK is worsening; it’s quite

low in the dawn twilight prior

to sunrise. A telescope will

now show its disc to have a

gibbous phase. At the start

of April, Venus appears to be

22 arcseconds across with a

phase of 54%. By month end,

this will have changed to

17 arcseconds and a phase of

66%. Look out for attractive

conjunctions between Venus

and the waning crescent moon

in the east-southeast dawn sky

on the 25th and 26th.

JUpITeR BeST Time in aPRiL: 1 April, 21:30 BST (20:30 UT)aLTiTude: 52º LoCaTion: GeminidiReCTion: SouthwestJupiter is best seen at the start

of April, when its impressive

mag. –1.2 dot can be seen 52º

up in the southwest as the

sky darkens. At the start of

April the planet shows a

38-arcsecond disc when

viewed through a telescope,

plenty big enough to show

some great detail even with

small instruments. on the

6th, the waxing crescent

moon (45% lit) lies 6º below

the planet. By the end of the

month, the distance between

us and Jupiter will have

increased, resulting in the

planet appearing slightly

smaller at 35 arcseconds

across, and slightly fainter at

mag. –1.9. The planet remains

in Gemini all month.

sATURN BeST Time in aPRiL: 30 April, 02:00 BST (01:00 UT) aLTiTude: 21º LoCaTion: LibradiReCTion: SouthSitting in the constellation

of Libra, Saturn doesn’t get

very high above the UK’s

southern horizon, even when

due south. Don’t let that deter

you though. if you have a

telescope, it’s defnitely worth

trying to get a view of this

beautiful planet.

At the start of April, Saturn

is mag. +0.6 and its disc

appears to be 18 arcseconds

across. it rises at 22:30 BST

(21:30 UT) on the 1st and

manages to reach its highest

point in the sky, 21º up and

due south, in darkness. The

almost full moon lies just

2º from Saturn in the early

hours of 17 April. Look out

for the pair low in the

southwest at around 05:30

BST (04:30 UT). At the end

of the month, Saturn is

visible all night long and

this is the best time to try

and get a view of it.

NOT VISIBLE THIS MONTHURANUs, NepTUNe

AprilUsing a small scope you’ll be able to spot Saturn’s biggest moons. their positions change dramatically during the month, as shown on the diagram. the line by each date on the left represents midnight.

SaT u R n ’S m o o nS

arcminutes

DATE WEST EAST

3210123

2

1

3

5

4

6

8

7

9

11

10

12

14

13

15

17

16

18

20

19

21

23

22

24

25

26

28

27

29

30

1

Dione Rhea TitanTethys Iapetus Saturn

See what the planets look like through your telescope with the feld of view calculator on our website at:

http://www.skyatnightmagazine.com/astronomy-tools


The Northern Hemisphere

monday tuesday wednesday thursday friday saturday sunday

Summ

er Triangle

Keystone

Northern Cross

R

39

M13

M92

M57

M5

HERCULES

CYGN

US

CORO

NA

BOREALIS

SERPE

NS CAPU

T

LYRA

OPHIUCHUS

LIBRA

α

β

γ

αβ

γδ

γ

β

αβγ

α

β

γ

δ

α

α

γβ

δ

α

δ

γβ

δ

β

δ Oph

η

ζ

Deneb

Vega

Rasalgethi

Rasalhague

Albireo

Saturn

April LyridsPeaks 22 April

16th

Deep

-sky

tour, p

57

NORTHEAST

EA

ST

SOUTHEAST

HOW to use this chart1. hold the chart so the direction you’re facing

is at the bottom.2. the lower half of the chart shows the sky

ahead of you.3. the centre of the chart is the point

directly over your head.

THe Sun in aPril*

*times correct for the centre of the uK

date sunrise sunset01 apr 2014 06:43 Bst 19:45 Bst

11 apr 2014 06:20 Bst 20:03 Bst

21 apr 2014 05:57 Bst 20:21 Bst

01 may 2014 05:35 Bst 20:39 Bst

moonrise times01 apr 2014, 07:23 Bst 17 apr 2014, 23:02 Bst

05 apr 2014, 09:58 Bst 21 apr 2014, 01:54 Bst

09 apr 2014, 13:51 Bst 25 apr 2014, 04:05 Bst

13 apr 2014, 18:17 Bst 29 apr 2014, 05:52 Bst

THe MOOn in aPril*

1 aPril at 01:00 Bst 15 aPril at 00:00 Bst30 aPril at 23:00 BstOn other dates, use the interactive planetarium on our website at www.skyatnightmagazine.com/interactive-planetarium

WHen to use this chart

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

21 22 23 24 25 26 27

28 29 30

fuLL moon

new moon

58

PERSEUS

Arcturus

Circlet

N

E

S

W

5º

STAR NAME

CONSTELLATION

NAME

GALAXY

OPEN CLUSTER

GLOBULAR

CLUSTER

PLANETARY

NEBULA

DIFFUSE

NEBULOSITY

DOUBLE STAR

VARIABLE STAR

THE MOON,

SHOWING PHASE

COMET TRACK

ASTEROID

TRACK

STAR-HOPPING

PATH

METEOR

RADIANT

ASTERISM

PLANET

QUASAR

STAR BRIGHTNESS:

MAG. 0

& BRIGHTER

MAG. +1

MAG. +2

MAG. +3

MAG. +4

& FAINTER

MILKY WAY

COMPASS AND

FIELD OF VIEW

Key to

star charts


The Northern Hemisphere

monday tuesday wednesday thursday friday saturday sunday

Summ

er Triangle

Keystone

Northern Cross

R

39

M13

M92

M57

M5

HERCULES

CYGN

US

CORO

NA

BOREALIS

SERPE

NS CAPU

T

LYRA

OPHIUCHUS

LIBRA

α

β

γ

αβ

γδ

γ

β

αβγ

α

β

γ

δ

α

α

γβ

δ

α

δ

γβ

δ

β

δ Oph

η

ζ

Deneb

Vega

Rasalgethi

Rasalhague

Albireo

Saturn

April LyridsPeaks 22 April

16th

Deep

-sky

tour, p

57

NORTHEAST

EA

ST

SOUTHEAST

HOW to use this chart1. hold the chart so the direction you’re facing

is at the bottom.2. the lower half of the chart shows the sky

ahead of you.3. the centre of the chart is the point

directly over your head.

THe Sun in aPril*

*times correct for the centre of the uK

date sunrise sunset01 apr 2014 06:43 Bst 19:45 Bst

11 apr 2014 06:20 Bst 20:03 Bst

21 apr 2014 05:57 Bst 20:21 Bst

01 may 2014 05:35 Bst 20:39 Bst

moonrise times01 apr 2014, 07:23 Bst 17 apr 2014, 23:02 Bst

05 apr 2014, 09:58 Bst 21 apr 2014, 01:54 Bst

09 apr 2014, 13:51 Bst 25 apr 2014, 04:05 Bst

13 apr 2014, 18:17 Bst 29 apr 2014, 05:52 Bst

THe MOOn in aPril*

1 aPril at 01:00 Bst 15 aPril at 00:00 Bst30 aPril at 23:00 BstOn other dates, use the interactive planetarium on our website at www.skyatnightmagazine.com/interactive-planetarium

WHen to use this chart

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

21 22 23 24 25 26 27

28 29 30

fuLL moon

new moon

58

PERSEUS

Arcturus

Circlet

N

E

S

W

5º

STAR NAME

CONSTELLATION

NAME

GALAXY

OPEN CLUSTER

GLOBULAR

CLUSTER

PLANETARY

NEBULA

DIFFUSE

NEBULOSITY

DOUBLE STAR

VARIABLE STAR

THE MOON,

SHOWING PHASE

COMET TRACK

ASTEROID

TRACK

STAR-HOPPING

PATH

METEOR

RADIANT

ASTERISM

PLANET

QUASAR

STAR BRIGHTNESS:

MAG. 0

& BRIGHTER

MAG. +1

MAG. +2

MAG. +3

MAG. +4

& FAINTER

MILKY WAY

COMPASS AND

FIELD OF VIEW

Key to

star charts

Celesti

al Equa

torEclip

tic

Kite

House

W

Sick

le

Plough

U

RR

X

T

S

R

X

U

M39

M51

M103

M52

Dou

ble

Clu

ster

M34

M81

M82

M101

M38

M36

M37

M35

M44

M67

M63

M65

M66

M53

M64

M96 M

48

M94

M3

M102

M61

M49

M60

M90

M91 M88

M10

5

M95

M58

M84M86

M98M99

M100

M59

M87

M104

URSAMAJOR

DRA

CO

URSA

MIN

OR

CEPHEUS

ANDROMEDA

CASSIOPEIA PERSEU

S

CA

MEL

OPA

RDA

LIS

AU

RIG

A

LYN

X

GEMINI

CANCER

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NIS

MIN

OR

LEO

LEO M

INOR

MO

NO

CER

OS

HYDR

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SEXTANS

CANESVENATICI

COMA

BERENICES

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BOÖTE

S

CRATER

CORVUS

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ORI

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ANTILA

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TAU

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γ

α

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α

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ι

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α

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α

β

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α

β

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γ

α

β

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β

γ

α

β

α

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δ

α

β γ

δ

α

β

δα

α

β

γδ

γ

δ

β

ι

μ

θ

ν

ρ

Thuban

Kochab

Polaris

Schedar

Mirp

hak

Algol

Cape

lla

Dubhe

MerakMizar

Alcor

Cor CaroliA

lderamin

Casto

r

Pollux

Elna

th

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Proc

yon

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Den

ebol

a

Alph

ard

Porrima

Arcturu

s

Spica

Vindemiatrix

Jupite

r

Mars1st 30th

April Virginids

PeakS 11 April

Gamma Virginids

Peaks 14 April

7th

13th

10th

16th

NORTH

SOUTH

SOUTH

WES

T

WES

T

N

ORTHW

EST

the sky guide APRIL 59


Celesti

al Equa

torEclip

tic

Kite

House

W

Sick

le

Plough

U

RR

X

T

S

R

X

U

M39

M51

M103

M52

Dou

ble

Clu

ster

M34

M81

M82

M101

M38

M36

M37

M35

M44

M67

M63

M65

M66

M53

M64

M96 M

48

M94

M3

M102

M61

M49

M60

M90

M91 M88

M10

5

M95

M58

M84M86

M98M99

M100

M59

M87

M104

URSAMAJOR

DRA

CO

URSA

MIN

OR

CEPHEUS

ANDROMEDA

CASSIOPEIA PERSEU

S

CA

MEL

OPA

RDA

LIS

AU

RIG

A

LYN

X

GEMINI

CANCER

CA

NIS

MIN

OR

LEO

LEO M

INOR

MO

NO

CER

OS

HYDR

A

SEXTANS

CANESVENATICI

COMA

BERENICES

VIRGO

BOÖTE

S

CRATER

CORVUS

NA

S

ORI

ON

ANTILALACERTA

TAU

RUS

γ

α

βδ

ε

β

α

γ

δ

α

β

γ

δ

α

ι

α

δ

β

γ

α

β

γ

δ

αβ

α

β

α

β γ

β

α

α

β

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α

β

γ

δ

α

α

αβ

α

β

γ

δ

α

β

δ

γ

α

β

δ

α β

β

γ

α

β

α

βγ

δ

α

β γ

δ

α

β

δα

α

β

γδ

γ

δ

β

ι

μ

θ

ν

ρ

Thuban

Kochab

Polaris

Schedar

Mirp

hak

Algol

Cape

lla

Dubhe

MerakMizar

Alcor

Cor Caroli

Alderam

in

Casto

r

Pollux

Elna

th

Kids

Proc

yon

Regulus

Den

ebol

a

Alph

ard

Porrima

Arcturu

s

Spica

Vindemiatrix

Jupite

r

Mars1st 30th

April Virginids

PeakS 11 April

Gamma Virginids

Peaks 14 April

7th

13th

10th

16th

NORTH

SOUTH

SOUTH

WES

T

WES

T

N

ORTHW

EST

the sky guide APRIL 59


60


M5 Our first port of call this month is the rather wonderful globular cluster known as M5.

Located within the constellation of Serpens Caput, quite close to the border with Virgo, M5’s appearance through an eyepiece is on a par with better-known M13 in Hercules. A small scope shows M5 to be condensed, with a hint of star resolution at the edges. A 6-inch telescope at 200x magnification should be capable of resolving the cluster to the core, revealing many distinctive ‘strings’ of stars. This is one of the oldest globular clusters known with an estimated age of 13 billion years. SEEN IT

PaloMar 5 Our next target is also a globular cluster, but this one is at the other end of the brightness

scale. Known as Palomar 5, this globular appears as little more than a smudge of light, and as such is best seen with large aperture scopes or via imaging. It has magnitude of +11.8 but is spread out, so its surface brightness is low. Find it 2.3º to the southwest of M5. The cluster is being disrupted by the gravitation of the Milky Way and there is evidence of streams of stars leaving it. For a while it was thought to be a dwarf galaxy. SEEN ITC

HA

rT A

nd

PH

OTO

: Pe

Te L

AW

ren

Ce

There’s much more to see in the skies around Libra than the ringed wonder of Saturn

Tick the box when you’ve seen each one ✓

Deep-sky tour

-20

ZubENESchaMalI Continue south from Palomar 5 and you’ll reach the constellation of Libra and our next

target – mag. +2.6 Zubeneschamali (Beta (β) Librae). This star is distinct because of reports that it appears to have a green tint. If true, this makes it the only greenish star in the sky visible to the naked eye. A star with peak output in the green part of the spectrum also emits blue and red light. Consequently, our eyes fail to see just green. So does Zubeneschamali actually look green? The only way to tell is to take a look yourself. SEEN IT

NGc 5897 One of the few deep-sky objects in the heart of Libra is globular cluster nGC 5897 – look

for it 1.5º southeast of mag. +4.5 Iota (ι) Librae. nGC 5897 is a broad, diffuse globular that can only be partially resolved, but at mag. +8.6 is considerably easier to identify than Palomar 5. The core looks quite uniform in brightness with no obvious central condensation. Brighter core stars can be made out individually, but the many fainter members merge together like a nebulous haze. There is a notable triple pattern of mag. +11.5 to mag. +13.5 stars located north-northwest of the cluster’s centre. SEEN IT

MErrIll 2-1 There’s another challenging object located 3º to the southeast of nGC 5897, a mag. +11.6

planetary nebula known as Merrill 2-1. This is a tricky spot: the nebula is relatively faint, quite small and located extremely close to a mag. +11.2 star. There’s a mag. +9.9 star designated SAO 183407 50 arcseconds to the west that serves as a good pointer to the area. Once you’ve found the nebula and its close mag. +11.2 star, don’t be afraid to pile on the magnification. At 150x magnification the nebula will start to look like a slightly blurred star. A 6- to 8-inch scope at 200x magnification is needed to show it convincingly. SEEN IT

18 lIbraE Our final object is double star 18 Librae. The primary star is a mag. +5.9 orange

giant that lies 316 lightyears from the Sun. It is fairly easy to locate, being the third point in a squat isosceles triangle that also includes Zubeneschamali (our third stop) and mag. +2.8 Zubenelgenubi (Alpha (α) Librae); the slightly brighter mag. +5.8 Xi1 (ξ1) and mag. +5.5 Xi2 (ξ2) Librae also point toward it. A small scope will reveal that the orange giant has a yellow, mag. +9.9 companion 19.7 arcseconds away. Also look out for a third, mag. +11.5 star 162 arcseconds to the northeast of the primary. SEEN IT

If you have a large scope, look for the ‘strings’ of stars

streaming from M5’s core

2

3

4

5

6

1

60


M5 Our first port of call this month is the rather wonderful globular cluster known as M5.

Located within the constellation of Serpens Caput, quite close to the border with Virgo, M5’s appearance through an eyepiece is on a par with better-known M13 in Hercules. A small scope shows M5 to be condensed, with a hint of star resolution at the edges. A 6-inch telescope at 200x magnification should be capable of resolving the cluster to the core, revealing many distinctive ‘strings’ of stars. This is one of the oldest globular clusters known with an estimated age of 13 billion years. SEEN IT

PaloMar 5 Our next target is also a globular cluster, but this one is at the other end of the brightness

scale. Known as Palomar 5, this globular appears as little more than a smudge of light, and as such is best seen with large aperture scopes or via imaging. It has magnitude of +11.8 but is spread out, so its surface brightness is low. Find it 2.3º to the southwest of M5. The cluster is being disrupted by the gravitation of the Milky Way and there is evidence of streams of stars leaving it. For a while it was thought to be a dwarf galaxy. SEEN ITC

HA

rT A

nd

PH

OTO

: Pe

Te L

AW

ren

Ce

There’s much more to see in the skies around Libra than the ringed wonder of Saturn


Deep-sky tour

-20

ZubENESchaMalI Continue south from Palomar 5 and you’ll reach the constellation of Libra and our next

target – mag. +2.6 Zubeneschamali (Beta (β) Librae). This star is distinct because of reports that it appears to have a green tint. If true, this makes it the only greenish star in the sky visible to the naked eye. A star with peak output in the green part of the spectrum also emits blue and red light. Consequently, our eyes fail to see just green. So does Zubeneschamali actually look green? The only way to tell is to take a look yourself. SEEN IT

NGc 5897 One of the few deep-sky objects in the heart of Libra is globular cluster nGC 5897 – look

for it 1.5º southeast of mag. +4.5 Iota (ι) Librae. nGC 5897 is a broad, diffuse globular that can only be partially resolved, but at mag. +8.6 is considerably easier to identify than Palomar 5. The core looks quite uniform in brightness with no obvious central condensation. Brighter core stars can be made out individually, but the many fainter members merge together like a nebulous haze. There is a notable triple pattern of mag. +11.5 to mag. +13.5 stars located north-northwest of the cluster’s centre. SEEN IT

MErrIll 2-1 There’s another challenging object located 3º to the southeast of nGC 5897, a mag. +11.6

planetary nebula known as Merrill 2-1. This is a tricky spot: the nebula is relatively faint, quite small and located extremely close to a mag. +11.2 star. There’s a mag. +9.9 star designated SAO 183407 50 arcseconds to the west that serves as a good pointer to the area. Once you’ve found the nebula and its close mag. +11.2 star, don’t be afraid to pile on the magnification. At 150x magnification the nebula will start to look like a slightly blurred star. A 6- to 8-inch scope at 200x magnification is needed to show it convincingly. SEEN IT

18 lIbraE Our final object is double star 18 Librae. The primary star is a mag. +5.9 orange

giant that lies 316 lightyears from the Sun. It is fairly easy to locate, being the third point in a squat isosceles triangle that also includes Zubeneschamali (our third stop) and mag. +2.8 Zubenelgenubi (Alpha (α) Librae); the slightly brighter mag. +5.8 Xi1 (ξ1) and mag. +5.5 Xi2 (ξ2) Librae also point toward it. A small scope will reveal that the orange giant has a yellow, mag. +9.9 companion 19.7 arcseconds away. Also look out for a third, mag. +11.5 star 162 arcseconds to the northeast of the primary. SEEN IT

If you have a large scope, look for the ‘strings’ of stars

streaming from M5’s core

2

3

4

5

6

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1 M92 Our tour starts with M92, a fine globular cluster that suffers from its proximity to a

far more illustrious one. Start at the northwest corner of the Keystone asterism in Hercules and imagine a line heading northeast to mag. +3.8 Iota (ι) Herculis. Two thirds of the way along this line, M92 shines at mag. +6.4; it has an apparent diameter about one fifth that of the Moon. When you find it, you’ll be looking at the light of a third of a million stars. SEEN IT

2 M13 M92’s more renowned neighbour is M13, which is called the ‘Great Cluster’ for good

reason. Situated a third of the way down the western side of the Keystone asterism, it is visible to the naked eye in a reasonably dark sky. even with small binoculars, this mag. +5.8 globular can be seen in urban skies, although not nearly as splendidly as it appears in darker conditions. In 10x50s, it brightens towards the centre. M13 contains over a million stars. SEEN IT

3 Nu coroNaE borEalIS Line-of-sight double star nu (ν) Coronae Borealis is an easy split in

small binoculars, its distinct deep yellow components appearing a wide 6 arcminutes apart. The pair are remarkably similar, both being advanced giants with masses about 2.5 times that of the Sun. The more northerly star, ν1, sits at 555 lightyears, just 10 lightyears farther away than ν2. It is also a fraction brighter, shining at mag. +5.2, 0.2 magnitudes brighter than ν2 – a result of being about 750 million years more advanced in its evolution and therefore larger and more luminous. SEEN IT

4 Tau coroNaE borEalIS GrouP

Move 4° to the northwest of nu Coranae Borealis and you’ll come to mag. +4.7

Tau (τ) Coronae Borealis, the brightest in a very pretty straight chain (2.5° long) of five stars running east to west. All but the central star shine brighter than mag. +6.0. notice that the

Explore the forgotten cousin of a famous globular, a pair of giants and a starry chain


Binocular tour

mag. +5.6 stars at each end of the chain are a

deeper yellow than the others, while the star next to the eastern end is almost white by comparison. You should find that the mag. +7.4 central star easily resolves into a triple star under dark skies or with larger binoculars. SEEN IT

5 DElTa boöTIS Our penultimate stop is another double star, mag. +3.5 delta (δ) Boötis. The

primary is a deep yellow giant star nearly 60 times more luminous than the Sun. Its yellow-white, mag. +7.8 companion appears to be 105 arcseconds away. delta Boötis is 117 lightyears away, and its components are moving through space together. This confirms that they are a binary star system: they have a separation of at least 0.6 lightyears and an orbital period of at least 120,000 years. SEEN IT

6 rV boöTIS The last stop on this month’s tour is rV Boötis (also designated HIP 71644),

which you can fnd 2.6° northeast of mag. +3.6 rho (ρ) Boötis. rV is nearly midway between two mag. +6.3 stars, the brightest stars in the feld of view of 15x70 binoculars. It is a semi-regular variable with a period between 137 and 144 days, which changes in brightness from mag. +7.2 to mag. +9.8 – although recently it has only been falling to mag. +8.8, so it remains well within reach of binoculars. rV Boötis is a red star, in the latter stage of evolution, on the giant branch of the Hertzsprung-russell diagram. SEEN IT

DRACO

Gemma

Seginus

Nekkar

ArcturusIzar

Muphrid

Kornephoros

Rastaban

HERCULESSERPENSCAPUT

BOÖTES

CORONABOREALIS

Keystone

Kite

M13

M92

β

α

γ

δ

α

γ

δ

β

ε

ρ

ση

ε

γ

β

δ

β γ

ε

ζ

η

π

θ

ι

τ

σ

β

ν

ν1

ν2

τ

RV

NE S

W

5º

1

2

3

4

5

6

With Stephen Tonkin


15 x70

10 x50

10 x50

10 x50

10 x50

15 x70

CH

ArT

S A

nd

PIC

Ture

S: P

eTe

LAW

ren

Ce

1 M92 Our tour starts with M92, a fine globular cluster that suffers from its proximity to a

far more illustrious one. Start at the northwest corner of the Keystone asterism in Hercules and imagine a line heading northeast to mag. +3.8 Iota (ι) Herculis. Two thirds of the way along this line, M92 shines at mag. +6.4; it has an apparent diameter about one fifth that of the Moon. When you find it, you’ll be looking at the light of a third of a million stars. SEEN IT

2 M13 M92’s more renowned neighbour is M13, which is called the ‘Great Cluster’ for good

reason. Situated a third of the way down the western side of the Keystone asterism, it is visible to the naked eye in a reasonably dark sky. even with small binoculars, this mag. +5.8 globular can be seen in urban skies, although not nearly as splendidly as it appears in darker conditions. In 10x50s, it brightens towards the centre. M13 contains over a million stars. SEEN IT

3 Nu coroNaE borEalIS Line-of-sight double star nu (ν) Coronae Borealis is an easy split in

small binoculars, its distinct deep yellow components appearing a wide 6 arcminutes apart. The pair are remarkably similar, both being advanced giants with masses about 2.5 times that of the Sun. The more northerly star, ν1, sits at 555 lightyears, just 10 lightyears farther away than ν2. It is also a fraction brighter, shining at mag. +5.2, 0.2 magnitudes brighter than ν2 – a result of being about 750 million years more advanced in its evolution and therefore larger and more luminous. SEEN IT

4 Tau coroNaE borEalIS GrouP

Move 4° to the northwest of nu Coranae Borealis and you’ll come to mag. +4.7

Tau (τ) Coronae Borealis, the brightest in a very pretty straight chain (2.5° long) of five stars running east to west. All but the central star shine brighter than mag. +6.0. notice that the

Explore the forgotten cousin of a famous globular, a pair of giants and a starry chain


Binocular tour

mag. +5.6 stars at each end of the chain are a

deeper yellow than the others, while the star next to the eastern end is almost white by comparison. You should find that the mag. +7.4 central star easily resolves into a triple star under dark skies or with larger binoculars. SEEN IT

5 DElTa boöTIS Our penultimate stop is another double star, mag. +3.5 delta (δ) Boötis. The

primary is a deep yellow giant star nearly 60 times more luminous than the Sun. Its yellow-white, mag. +7.8 companion appears to be 105 arcseconds away. delta Boötis is 117 lightyears away, and its components are moving through space together. This confirms that they are a binary star system: they have a separation of at least 0.6 lightyears and an orbital period of at least 120,000 years. SEEN IT

6 rV boöTIS The last stop on this month’s tour is rV Boötis (also designated HIP 71644),

which you can fnd 2.6° northeast of mag. +3.6 rho (ρ) Boötis. rV is nearly midway between two mag. +6.3 stars, the brightest stars in the feld of view of 15x70 binoculars. It is a semi-regular variable with a period between 137 and 144 days, which changes in brightness from mag. +7.2 to mag. +9.8 – although recently it has only been falling to mag. +8.8, so it remains well within reach of binoculars. rV Boötis is a red star, in the latter stage of evolution, on the giant branch of the Hertzsprung-russell diagram. SEEN IT

DRACO

Gemma

Seginus

Nekkar

ArcturusIzar

Muphrid

Kornephoros

Rastaban

HERCULESSERPENSCAPUT

BOÖTES

CORONABOREALIS

Keystone

Kite

M13

M92

β

α

γ

δ

α

γ

δ

β

ε

ρ

ση

ε

γ

β

δ

β γ

ε

ζ

η

π

θ

ι

τ

σ

β

ν

ν1

ν2

τ

RV

NE S

W

5º

1

2

3

4

5

6

With Stephen Tonkin


15 x70

10 x50

10 x50

10 x50

10 x50

15 x70



being about 5km deep. Under

good seeing conditions and the

right illumination these cliffs

can be most impressive. The

crater’s foor is largely fat, but

shows a variety of different

tones and textures. To give

you a sense of scale, Humboldt

covers an area of 35,000

square km, which is about 1.5

times the size of Wales.

There is a central mountain

complex and a curious curve

of smaller mountains and hills

arcing off to the northeast. A

smaller, 15km-diameter crater

known as Humboldt N can be

seen to the west, in the

foreground, of this curving

range. This crater and the

mountain range provide the

most obvious visual features

within Humboldt’s rim.

Look carefully and it may be

possible to make out that the

foor of the crater isn’t evenly

toned. There are pyroclastic

patches – dark deposits left

over from volcanic activity

– visible in certain parts of

the foor, most notably in the

southwest round to the west,

and in the northeast.

Moonwatch

CrATer HUmboLdT is

located in the zone of libration

close to the eastern limb of the

moon. The easiest way to fnd

it is to frst identify the more

favourably positioned, 182km-

wide crater Petavius.

Petavius lies 500km to the

west of Humboldt, a distance

that looks much smaller due

to foreshortening at the

moon’s edge. even knowing

this fact, Humboldt can still

be a tricky feature to get to

grips with. in order to see it

convincingly the moon’s

phase has to be just right, as

does the libration. As the

crater is so close to the edge of

the moon, our view of it from

earth foreshortens it into an

ellipse. it can be challenging

to pull the crater out from the

surrounding landscape, but

vigilance reaps rewards.

The crater’s rim is well

defned and lined by some

rather steep cliffs, Humboldt

a number of easily identifable features sit within humboldt’s rim – these include a central peak complex, a mountain range and smaller craters

seen from above by orbiting

spacecraft, Humboldt displays

a delicate pattern of radial

fractures that resembles a

spider’s web. These cracks are

very diffcult to see visually

from earth, but present a

good challenge if you’re into

high-resolution imaging.

Foreshortened regions of

the moon can be very diffcult

to decode. between Petavius

and Humboldt lies 82km-wide

crater Legendre; many of the

smaller craters between it and

Humboldt are catalogued as

being part of the Legendre

family. one notable exception

is the tormented 128km-wide

crater Philips, which sidles up

to the west rim of Humboldt.

if the conditions are really

good, see if you can fnd the

104km-wide crater barnard,

which sits against the southeast

rampart of Humboldt even

nearer to the moon’s edge.

over the coming months

Humboldt’s position will get

less favourable at the same

lunar phase, so make the most

of the conditions during April

to see this amazing crater.

STATISTICSTyPE: CraterSIZE: 213km wide aGE: 3.2 to 3.8 billion years oldlocaTIoN: Latitude 27.2°S, longitude 80.0°E bEST TIME To obSErVE: Two days after new Moon or one day after full Moon (1 and 2 April from 20:00 BST; 30 April and 1 May from 21:00 BST) MINIMuM EquIPMENT: 10x binoculars

Humboldt

“To give you a sense of scale, Humboldt covers an area of 35,000 square km, which is about 1.5 times the size of Wales”

N

E

huMbolDT

huMbolDT N



being about 5km deep. Under

good seeing conditions and the

right illumination these cliffs

can be most impressive. The

crater’s foor is largely fat, but

shows a variety of different

tones and textures. To give

you a sense of scale, Humboldt

covers an area of 35,000

square km, which is about 1.5

times the size of Wales.

There is a central mountain

complex and a curious curve

of smaller mountains and hills

arcing off to the northeast. A

smaller, 15km-diameter crater

known as Humboldt N can be

seen to the west, in the

foreground, of this curving

range. This crater and the

mountain range provide the

most obvious visual features

within Humboldt’s rim.

Look carefully and it may be

possible to make out that the

foor of the crater isn’t evenly

toned. There are pyroclastic

patches – dark deposits left

over from volcanic activity

– visible in certain parts of

the foor, most notably in the

southwest round to the west,

and in the northeast.

Moonwatch

CrATer HUmboLdT is

located in the zone of libration

close to the eastern limb of the

moon. The easiest way to fnd

it is to frst identify the more

favourably positioned, 182km-

wide crater Petavius.

Petavius lies 500km to the

west of Humboldt, a distance

that looks much smaller due

to foreshortening at the

moon’s edge. even knowing

this fact, Humboldt can still

be a tricky feature to get to

grips with. in order to see it

convincingly the moon’s

phase has to be just right, as

does the libration. As the

crater is so close to the edge of

the moon, our view of it from

earth foreshortens it into an

ellipse. it can be challenging

to pull the crater out from the

surrounding landscape, but

vigilance reaps rewards.

The crater’s rim is well

defned and lined by some

rather steep cliffs, Humboldt

a number of easily identifable features sit within humboldt’s rim – these include a central peak complex, a mountain range and smaller craters

seen from above by orbiting

spacecraft, Humboldt displays

a delicate pattern of radial

fractures that resembles a

spider’s web. These cracks are

very diffcult to see visually

from earth, but present a

good challenge if you’re into

high-resolution imaging.

Foreshortened regions of

the moon can be very diffcult

to decode. between Petavius

and Humboldt lies 82km-wide

crater Legendre; many of the

smaller craters between it and

Humboldt are catalogued as

being part of the Legendre

family. one notable exception

is the tormented 128km-wide

crater Philips, which sidles up

to the west rim of Humboldt.

if the conditions are really

good, see if you can fnd the

104km-wide crater barnard,

which sits against the southeast

rampart of Humboldt even

nearer to the moon’s edge.

over the coming months

Humboldt’s position will get

less favourable at the same

lunar phase, so make the most

of the conditions during April

to see this amazing crater.

STATISTICSTyPE: CraterSIZE: 213km wide aGE: 3.2 to 3.8 billion years oldlocaTIoN: Latitude 27.2°S, longitude 80.0°E bEST TIME To obSErVE: Two days after new Moon or one day after full Moon (1 and 2 April from 20:00 BST; 30 April and 1 May from 21:00 BST) MINIMuM EquIPMENT: 10x binoculars

Humboldt

“To give you a sense of scale, Humboldt covers an area of 35,000 square km, which is about 1.5 times the size of Wales”

N

E

huMbolDT

huMbolDT N

64

mArs is A bit of a tease as far as practical

astronomy is concerned. After lurking in

tricky parts of the sky and looking rather

diminutive for many months, it bursts

back onto the scene for a short period, before

fading into the background once again.

This month it reaches opposition, so this

is the best time to both observe and image

it. Here, we’ll look at how to do the latter

with a mono high frame rate camera and

a set of rGb imaging flters.

mars is a captivating astrophotography

target because it is the closest world we can

see that has reasonable similarity to earth,

in that it shows both surface features and

weather. From earth we can see brighter

deserts, darker rock and gleaming polar

caps. These are ‘albedo features’; they are

visible because they have notably different

refectivity (albedo) to adjacent areas.

Features such as craters, mountains and

valleys are much harder to image from

earth because of their small apparent size

at the planet’s vast distance. Known as

AstrophotographyImaging Mars at opposition

ALL

PIC

Tu

reS: PeTe L

AW

ren

Ce

need to try and complete the entire

capture sequence in less than fve minutes.

For a colour camera this isn’t too hard,

but when trying to capture images using

several flters it is more of a concern.

Advanced processing techniques such as

derotation can be used to address motion

blur, but there’s an easier solution that

hinges around the lack of signifcant detail

visible in the green flter – simply abstain

from taking a green-fltered image in the

frst place. it may sound crazy, but the green

image can be artifcially synthesised from

the red and blue results. The fnal colour

image will look almost identical to what

you would have achieved using a full set of

rGb images, but you’ll reduce the time it

needed for your capture sequence by a third.

Generating a synthetic green image also

streamlines the capture process, allowing

you to generate a smooth sequence of

mars images for animation purposes. For

example, a run of rbrbrb captures would

allow you to create an r(G)b result using

the frst rb pair – the parentheses indicate

that the green is synthetic – then

a second b(G)r result using the frst br

pair. A third r(G)b result would be created

using the second rb pair, and so on. With

a fairly short time gap between r(G)b

results, these can be animated together

to produce a smooth fowing rotation

sequence of this fascinating world.

‘relief’ features, these would normally be

revealed because height variation causes

them to cast shadows, just like elevated

structures close to the terminator do

on the moon. From earth, the martian

shadows are tiny and hard to pick out,

so the main features of interest for mars

imagers are albedo based rather than relief.

Using a mono high frame rate camera

and rGb flters, mars’s refectivity

becomes quite interesting – the reason for

this is that the ‘information’ that passes

through a green flter gives very little

extra image detail than can be obtained

with red and blue flters alone. This

surprising fact can be used to help

overcome one of the main issues when

rGb imaging a relatively fast rotating

planet such as mars: if you take too long

to collect an image set, the fnal rGb may

show motion blur. For this reason, you

Send your image to: [email protected]


ReCommended equIPmenT8-inch or larger scope, Barlow lens, monochrome high frame rate camera, RGB imaging flters mounted in a flter wheel

Key TeChnIqueSyNThETIc colourSAlthough colour cameras are catching up, mono cameras still have the edge when it comes to planetary imaging. For a full-colour result from a mono camera you need red, green and blue imaging filters; this significantly reduces colour-related problems such as chromatic aberration and atmospheric dispersion. Unfortunately, filtered sequences take longer to complete and overly long capture may result in motion blur – but using a synthetic green capture can help. Find out how in the step-by-step.

your fnal image will reveal the red

Planet’s large albedo surface features

64

mArs is A bit of a tease as far as practical

astronomy is concerned. After lurking in

tricky parts of the sky and looking rather

diminutive for many months, it bursts

back onto the scene for a short period, before

fading into the background once again.

This month it reaches opposition, so this

is the best time to both observe and image

it. Here, we’ll look at how to do the latter

with a mono high frame rate camera and

a set of rGb imaging flters.

mars is a captivating astrophotography

target because it is the closest world we can

see that has reasonable similarity to earth,

in that it shows both surface features and

weather. From earth we can see brighter

deserts, darker rock and gleaming polar

caps. These are ‘albedo features’; they are

visible because they have notably different

refectivity (albedo) to adjacent areas.

Features such as craters, mountains and

valleys are much harder to image from

earth because of their small apparent size

at the planet’s vast distance. Known as

AstrophotographyImaging Mars at opposition

ALL

PIC

Tu

reS:

PeTe L

AW

ren

Ce

need to try and complete the entire

capture sequence in less than fve minutes.

For a colour camera this isn’t too hard,

but when trying to capture images using

several flters it is more of a concern.

Advanced processing techniques such as

derotation can be used to address motion

blur, but there’s an easier solution that

hinges around the lack of signifcant detail

visible in the green flter – simply abstain

from taking a green-fltered image in the

frst place. it may sound crazy, but the green

image can be artifcially synthesised from

the red and blue results. The fnal colour

image will look almost identical to what

you would have achieved using a full set of

rGb images, but you’ll reduce the time it

needed for your capture sequence by a third.

Generating a synthetic green image also

streamlines the capture process, allowing

you to generate a smooth sequence of

mars images for animation purposes. For

example, a run of rbrbrb captures would

allow you to create an r(G)b result using

the frst rb pair – the parentheses indicate

that the green is synthetic – then

a second b(G)r result using the frst br

pair. A third r(G)b result would be created

using the second rb pair, and so on. With

a fairly short time gap between r(G)b

results, these can be animated together

to produce a smooth fowing rotation

sequence of this fascinating world.

‘relief’ features, these would normally be

revealed because height variation causes

them to cast shadows, just like elevated

structures close to the terminator do

on the moon. From earth, the martian

shadows are tiny and hard to pick out,

so the main features of interest for mars

imagers are albedo based rather than relief.

Using a mono high frame rate camera

and rGb flters, mars’s refectivity

becomes quite interesting – the reason for

this is that the ‘information’ that passes

through a green flter gives very little

extra image detail than can be obtained

with red and blue flters alone. This

surprising fact can be used to help

overcome one of the main issues when

rGb imaging a relatively fast rotating

planet such as mars: if you take too long

to collect an image set, the fnal rGb may

show motion blur. For this reason, you

Send your image to: [email protected]


ReCommended equIPmenT8-inch or larger scope, Barlow lens, monochrome high frame rate camera, RGB imaging flters mounted in a flter wheel

Key TeChnIqueSyNThETIc colourSAlthough colour cameras are catching up, mono cameras still have the edge when it comes to planetary imaging. For a full-colour result from a mono camera you need red, green and blue imaging filters; this significantly reduces colour-related problems such as chromatic aberration and atmospheric dispersion. Unfortunately, filtered sequences take longer to complete and overly long capture may result in motion blur – but using a synthetic green capture can help. Find out how in the step-by-step.

your fnal image will reveal the red

Planet’s large albedo surface features



STeP-By-STeP GuIde

sTep 2 With Mars on chip, select the red flter and focus as quickly and accurately as possible. aim to collect 2,000-3,000 frames, although try to avoid imaging for more than 90 seconds per flter. adjust the camera gain and frame rate if necessary to maximise the saturation level for each flter to around 80-90 per cent.

sTep 3 Switch to your blue flter, quickly re-focus and capture the blue image. repeat the rb sequence as many times as required. When done, load each capture into a stacking program, such as the freeware regiStax, and process each through to wavelet sharpening. apply a subtle amount of wavelet sharpening to the end result as required.

sTep 6 Switch to the layers list and duplicate the base r(G)b layer to make your fnal tweaks. If the colour looks off or subdued, try using the program’s auto-colour function; if the colours look too strong after this, try fading the auto-colour back a bit. adjust the fnal levels, contrast and brightness to taste. apply sharpening sparingly.

sTep 1 Mars has an apparent diameter of 15 arcseconds at opposition, so you’ll need a decent image scale to show much detail. as a guide, aim for a focal ratio of between f/15 and f/45, adjusted by using optical amplifers such as a barlow lens. only use a high image scale if the seeing is good.

sTep 4 load an rb pair into a layer-based editor as separate layers. adjust the upper image so that it is aligned with the lower one. crop to remove any whites edges this creates. Duplicate the r and b layers and move to the top of layer stack. Make top layer 50 per cent transparent and merge with the one below – this creates the synthetic green.

sTep 5 create a blank rGb image with the same dimensions as the image you were working on in step 4. copy the r image layer to the red channel in the blank image. repeat for the (G) and b layers, pasting them into their respective green and blue channels. The result should be a full colour r(G)b image showing the distinctive colours of Mars.



STeP-By-STeP GuIde

sTep 2 With Mars on chip, select the red flter and focus as quickly and accurately as possible. aim to collect 2,000-3,000 frames, although try to avoid imaging for more than 90 seconds per flter. adjust the camera gain and frame rate if necessary to maximise the saturation level for each flter to around 80-90 per cent.

sTep 3 Switch to your blue flter, quickly re-focus and capture the blue image. repeat the rb sequence as many times as required. When done, load each capture into a stacking program, such as the freeware regiStax, and process each through to wavelet sharpening. apply a subtle amount of wavelet sharpening to the end result as required.

sTep 6 Switch to the layers list and duplicate the base r(G)b layer to make your fnal tweaks. If the colour looks off or subdued, try using the program’s auto-colour function; if the colours look too strong after this, try fading the auto-colour back a bit. adjust the fnal levels, contrast and brightness to taste. apply sharpening sparingly.

sTep 1 Mars has an apparent diameter of 15 arcseconds at opposition, so you’ll need a decent image scale to show much detail. as a guide, aim for a focal ratio of between f/15 and f/45, adjusted by using optical amplifers such as a barlow lens. only use a high image scale if the seeing is good.

sTep 4 load an rb pair into a layer-based editor as separate layers. adjust the upper image so that it is aligned with the lower one. crop to remove any whites edges this creates. Duplicate the r and b layers and move to the top of layer stack. Make top layer 50 per cent transparent and merge with the one below – this creates the synthetic green.

sTep 5 create a blank rGb image with the same dimensions as the image you were working on in step 4. copy the r image layer to the red channel in the blank image. repeat for the (G) and b layers, pasting them into their respective green and blue channels. The result should be a full colour r(G)b image showing the distinctive colours of Mars.

As two more sites in northern England and Scotland earn Dark Sky status, Paul F Cockburn hears how they achieved the award

Light pollution has been a

growing problem for the past

century, which has seen our

view of the night sky obscured

by the glow of artifcial lighting.

Since 2003, the annual International

Dark Sky Week – this year’s is 20-26

April – has become an umbrella for

events that remind people not just of the

wonder and beauty above their heads,

but also how light pollution can disrupt

the natural environment, waste energy

and affect human health. One ongoing

response has been the identifcation,

recognition and protection of areas

around the world that are still largely

free of signifcant light pollution.

It started in 2006, when the US-based

International Dark Sky Association

established a programme to classify Dark

Sky Parks, Reserves and Communities.

Galloway Forest Park in Scotland was

the frst area in the UK to ft the bill,

attaining Dark Sky status in 2009; the

Island of Sark and Exmoor National

Park followed suit in 2011, then Brecon

Beacons National Park in early 2013.

December 2013 saw two more, bringing

the UK’s total to six: Northumberland

National Park joined with neighbouring

Kielder Water and Forest Park to create

a single Dark Sky Park, and the Island

of Coll in Scotland became a Dark

Sky Community. We spoke to some

of the people who made these latest

designations possible. KIL

ED

ER W

ATER A

ND

FO

REST P

ARK

Dark skiesRECOGNISEDAs two more sites in northern England and Scotland earn Dark Sky status, Paul F Cockburn hears how they achieved the award

Light pollution has been a

growing problem for the past

century, which has seen our

view of the night sky obscured

by the glow of artifcial lighting.

Since 2003, the annual International

Dark Sky Week – this year’s is 20-26

April – has become an umbrella for

events that remind people not just of the

wonder and beauty above their heads,

but also how light pollution can disrupt

the natural environment, waste energy

and affect human health. One ongoing

response has been the identifcation,

recognition and protection of areas

around the world that are still largely

free of signifcant light pollution.

It started in 2006, when the US-based

International Dark Sky Association

established a programme to classify Dark

Sky Parks, Reserves and Communities.

Galloway Forest Park in Scotland was

the frst area in the UK to ft the bill,

attaining Dark Sky status in 2009; the

Island of Sark and Exmoor National

Park followed suit in 2011, then Brecon

Beacons National Park in early 2013.

December 2013 saw two more, bringing

the UK’s total to six: Northumberland

National Park joined with neighbouring

Kielder Water and Forest Park to create

a single Dark Sky Park, and the Island

of Coll in Scotland became a Dark

Sky Community. We spoke to some

of the people who made these latest

designations possible. KIL

ED

ER W

ATER A

ND

FO

REST P

ARK

Dark skiesRECOGNISED

ABOUT THE WRITER

Paul F Cockburn is a freelance journalist who has been writing about science and technology – past and future – since 1996.

The success of Kielder Observatory made applying for

Dark Sky status a natural step

ABOUT THE WRITER

Paul F Cockburn is a freelance journalist who has been writing about science and technology – past and future – since 1996.

The success of Kielder Observatory made applying for

Dark Sky status a natural step

68


“Tranquility has been

recognised as one of the

main special qualities

of Northumberland National Park,”

says chief executive Tony Gates. “That

sense of the unspoilt, which is

something that we know residents

and visitors really value, we felt also

extended to the skies.”

So, when applying for Dark Sky Park

status, Gates believes they started from

a very good base. “We needed to change

very little really,” he says. “The survey

of our existing skies, which was part of

the application, showed we already had

a very high level of darkness, which led

to us being designated gold status.

“Our intention was always to ensure

we protected the levels of dark skies

and, where there were opportunities

to enhance them, that we did,” Gates

adds. “What we’ve found through this

process is that people have really come

on board: it’s really tapped into just

how much they value the dark skies.

We had people voluntarily adjusting

the angles of outdoor spotlights,

adjusting the fttings.”

Adding weight to Northumberland

National Park’s application was the

fact that it was jointly made with

neighbouring Kielder Water and Forest

Park. “In their case the application was

largely driven by the popularity of the

Kiedler Observatory and the sudden

realisation that the dark skies were really

widely valued,” says Gates. “It just so

happened that the two parks were working

on this idea at the same time, so we

decided to put our lot together.”

Northumberland National Park

The initial inspiration behind attaining Dark Sky status was simple, according to chair of the

Kielder Water and Forest Park Development Trust, Heidi Mottram – it was the success of the Kielder Observatory, opened in 2008.

The trust has long been looking for new ways to promote economic

development in the area, as a way of helping ensure it remains a vibrant, living community.

“The idea really came from the Kielder Observatory and just grew,” says Mottram. “The local community became quite excited about it. At one level I think we already knew that the sky was stunning, that we had a fabulous asset, that it was pretty dark and that the changes required by the lighting audits were generally

Kielder Water and Forest Park

minor – a large part of the park is uninhabited anyway.”

She adds that the engagement of local communities has been great. “At one primary school, the children really got into it and designed covers for the school’s unshielded lights,” she says. “They really embraced the whole thing. One of the villages has had its lights replaced with LED units – there have been some changes, but nothing I would describe as massive.”

TONY GATES Chief executive

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Quite early on, the trust linked up with the application being made by neighbouring Northumberland National Park. “In many respects, that way of working is embedded here,” Mottram says.

“People in these communities recognise that because they’re so small on their own, it’s often diffcult to do anything. The two parks are side by side; it was obvious we should work together.”

HEIDI MOTTRAM Chairperson

Comet Hale-Bopp shines bright in the darkness of


A sycamore stands alone against the starry

skyscape over Kielder

68


“Tranquility has been

recognised as one of the

main special qualities

of Northumberland National Park,”

says chief executive Tony Gates. “That

sense of the unspoilt, which is

something that we know residents

and visitors really value, we felt also

extended to the skies.”

So, when applying for Dark Sky Park

status, Gates believes they started from

a very good base. “We needed to change

very little really,” he says. “The survey

of our existing skies, which was part of

the application, showed we already had

a very high level of darkness, which led

to us being designated gold status.

“Our intention was always to ensure

we protected the levels of dark skies

and, where there were opportunities

to enhance them, that we did,” Gates

adds. “What we’ve found through this

process is that people have really come

on board: it’s really tapped into just

how much they value the dark skies.

We had people voluntarily adjusting

the angles of outdoor spotlights,

adjusting the fttings.”

Adding weight to Northumberland

National Park’s application was the

fact that it was jointly made with

neighbouring Kielder Water and Forest

Park. “In their case the application was

largely driven by the popularity of the

Kiedler Observatory and the sudden

realisation that the dark skies were really

widely valued,” says Gates. “It just so

happened that the two parks were working

on this idea at the same time, so we

decided to put our lot together.”


The initial inspiration behind attaining Dark Sky status was simple, according to chair of the

Kielder Water and Forest Park Development Trust, Heidi Mottram – it was the success of the Kielder Observatory, opened in 2008.

The trust has long been looking for new ways to promote economic

development in the area, as a way of helping ensure it remains a vibrant, living community.

“The idea really came from the Kielder Observatory and just grew,” says Mottram. “The local community became quite excited about it. At one level I think we already knew that the sky was stunning, that we had a fabulous asset, that it was pretty dark and that the changes required by the lighting audits were generally

Kielder Water and Forest Park

minor – a large part of the park is uninhabited anyway.”

She adds that the engagement of local communities has been great. “At one primary school, the children really got into it and designed covers for the school’s unshielded lights,” she says. “They really embraced the whole thing. One of the villages has had its lights replaced with LED units – there have been some changes, but nothing I would describe as massive.”

TONY GATES Chief executive

ALA

MY,

KIL

EDER

WA

TER

AN

D F

ORE

ST P

ARK

, W

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GA

TER,

ALE

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Quite early on, the trust linked up with the application being made by neighbouring Northumberland National Park. “In many respects, that way of working is embedded here,” Mottram says.

“People in these communities recognise that because they’re so small on their own, it’s often diffcult to do anything. The two parks are side by side; it was obvious we should work together.”

HEIDI MOTTRAM Chairperson

Comet Hale-Bopp shines bright in the darkness of


A sycamore stands alone against the starry

skyscape over Kielder

dark sky sites april 69


“We stared out with

just two designations

– Reserve and Park,”

says Bob Parks, executive director of the

International Dark Skies Association.

“Then we added Community. The system

evolves over time to take account of

the types of areas where people are

interested; we’re fnding, as we continue

to expand the programme, that one

size defnitely doesn’t ft all, so we’re

trying to make adjustments.”

So what are the current technical

distinctions between the different kinds

of Dark Sky places? “Starting at the

larger end of the spectrum, a ‘Reserve’

is not required to be protected by a

government entity,” Parks says. “You can

develop a Reserve around any property

that the community and residents

are interested in protecting. A ‘Park’

specifcally has to have public protection,

which also ensures it’s not private

land. On the municipal end of the

spectrum, ‘Community’ is for

townships and cities, places that

are incorporated entities.”

The association is also introducing

a category called Development of

Distinction. “That’s one step down the

chain for residential developments that

may not be a town or city, but have an

interest in protecting the development.

We’re actually looking now at another

designation, or modifying current

ones. For example, two islands are part

of the programme, and in both cases

ESA’s JUICE mission, due to launch in 2022, will study the Galilean moons in greater detail than ever before

BOB PARKS

Executive director

they did not ft in anything except

Community because they were protected

by natural boundaries; they didn’t

really have a buffer zone to make either

a Reserve.

“Some areas that aren’t surrounded

by water have that same issue,” he adds.

“If they are surrounded by public land,

they sometimes can’t really incorporate

that into the equation as a buffer zone

because there isn’t a township or local

authority in the area that’s able to

sign a declaration of intent to abide

by our guidelines.

It’s not all about darkness“We don’t look for quantities of

designation; we’re not looking to have

hundreds of these,” Parks insists.

“Any decision is based on the merits

of the application. What we look for

is extraordinary dedication to the

preservation of that area in the future.

It doesn’t matter whether the area is

as dark as it possibly can be; what

we’re looking for is a community that’s

willing to make the changes and have

the dedication to try to preserve that

for the next generation.

“These applications take a long

time to prepare: they’re not easy,”

he adds. “Some people get into them

and then fnd out pretty quickly that

these are not a quick path to fame

and fortune. Different countries now

want to have their own Dark Sky

Parks, but the level of cooperation

and collaboration required to get

all the different parties to agree to

something is diffcult. It takes a

sustained effort by a community over

a long period of time.”

International Dark Skies Association

Galloway was the frst Dark Sky place in the UK, earning its award in 2009

The UK now boasts six Dark Sky places, the others being Sark,

Exmoor and – shown here – the Brecon Beacons

dark sky sites april 69


“We stared out with

just two designations

– Reserve and Park,”

says Bob Parks, executive director of the

International Dark Skies Association.

“Then we added Community. The system

evolves over time to take account of

the types of areas where people are

interested; we’re fnding, as we continue

to expand the programme, that one

size defnitely doesn’t ft all, so we’re

trying to make adjustments.”

So what are the current technical

distinctions between the different kinds

of Dark Sky places? “Starting at the

larger end of the spectrum, a ‘Reserve’

is not required to be protected by a

government entity,” Parks says. “You can

develop a Reserve around any property

that the community and residents

are interested in protecting. A ‘Park’

specifcally has to have public protection,

which also ensures it’s not private

land. On the municipal end of the

spectrum, ‘Community’ is for

townships and cities, places that

are incorporated entities.”

The association is also introducing

a category called Development of

Distinction. “That’s one step down the

chain for residential developments that

may not be a town or city, but have an

interest in protecting the development.

We’re actually looking now at another

designation, or modifying current

ones. For example, two islands are part

of the programme, and in both cases

ESA’s JUICE mission, due to launch in 2022, will study the Galilean moons in greater detail than ever before

BOB PARKS

Executive director

they did not ft in anything except

Community because they were protected

by natural boundaries; they didn’t

really have a buffer zone to make either

a Reserve.

“Some areas that aren’t surrounded

by water have that same issue,” he adds.

“If they are surrounded by public land,

they sometimes can’t really incorporate

that into the equation as a buffer zone

because there isn’t a township or local

authority in the area that’s able to

sign a declaration of intent to abide

by our guidelines.

It’s not all about darkness“We don’t look for quantities of

designation; we’re not looking to have

hundreds of these,” Parks insists.

“Any decision is based on the merits

of the application. What we look for

is extraordinary dedication to the

preservation of that area in the future.

It doesn’t matter whether the area is

as dark as it possibly can be; what

we’re looking for is a community that’s

willing to make the changes and have

the dedication to try to preserve that

for the next generation.

“These applications take a long

time to prepare: they’re not easy,”

he adds. “Some people get into them

and then fnd out pretty quickly that

these are not a quick path to fame

and fortune. Different countries now

want to have their own Dark Sky

Parks, but the level of cooperation

and collaboration required to get

all the different parties to agree to

something is diffcult. It takes a

sustained effort by a community over

a long period of time.”

International Dark Skies Association

Galloway was the frst Dark Sky place in the UK, earning its award in 2009

The UK now boasts six Dark Sky places, the others being Sark,

Exmoor and – shown here – the Brecon Beacons


1 Brecon Beacons National Park International Dark Sky ReserveNational Park Visitor Centre Libanus, Brecon, Powys, LD3 8ER01874 623366www.beacons-npa.gov.uk/contact-us www.beacons-npa.gov.uk

2 Exmoor National ParkInternational Dark Sky ReserveDulverton National Park Centre7-9 Fore Street, Dulverton, TA22 9EX 01398 323841 [email protected] www.exmoor-nationalpark.gov.uk

3 Galloway Forest ParkInternational Dark Sky ParkGalloway Astronomy CentreA747, three miles east of Monreith01988 500594 [email protected] www.forestry.gov.uk/darkskygalloway

4 Isle of Coll International Dark Sky Communityc/o The Coll Hotel

Arinagour, Isle of Coll, PA78 6SZ01879 230334 [email protected] http://darkskies.visitcoll.co.uk

5 Northumberland National Park and Kielder Water and Forest Park International Dark Sky ParkOnce Brewed Visitor Centre Military Road, Bardon Mill, Hexham, NE47 7AN 01434 344396 [email protected] www.northumberlandnationalpark.org.uk

Kielder ObservatoryBlack Fell, Off Shilling Pot, Kielder, NE48 1EJ07805 638469 [email protected]

6 Isle of Sark International Dark Sky Communitywww.sark.co.uk Sark Tourist OffceThe Avenue, Sark Island, GY10 1SA01481 832345 [email protected]

Visiting the UK’s Dark Sky sites

70 dark sky sites april

“An International Dark

Sky Community is a

town, city, municipality,

or other legally organised community

that shows what the International Dark

Sky Association describes as ‘exceptional

dedication’ to preserving the night sky,”

explains amateur astronomer Olvin Smith,

who lives on the Inner Hebridean island

of Coll – since December 2013 the second

Dark Sky Community in Britain.

“It started around two years ago when

fellow astronomer Tony Oliver saw that Sark

had been awarded the status and thought

that we should get it as well,” Smith says.

“This led to a meeting which ended up

with a core group of four – myself, Tony,

hotel owner Julie Oliphant and guest house

owner Paula Smalley taking it forward. We

got in touch with the association, and had a

couple of phone calls with chief executive Bob

Parks, who talked us through the process.

Having purchased a Unihedron [sky quality]

meter, Smith completed a light survey

around the island. “On several sites I got

readings of 21.9 [magnitudes per square

arcsecond], which make our skies some of

the darkest in Europe,” he says. “Once we

had all the data, and with the help of a dark

skies consultant, Tony put together our

application, which was fnished last May.

“We had to alter some of the lights to

make them point straight down and get

commitment from some people to change

their outside lights to correct type,” Smith

notes. “We also needed to get the council

to endorse our lighting plan.”

It’s been very much a ‘ground up’

affair, Smith insists. “The community

has done all the work without any outside

funding; the money and work came

from the islanders.”

Isle of CollOLvIN SMITH

Amateur astronomer

CO

LL D

ARK

SK

Y G

RO

UP

1

2

3

4

5

6

Coll is Britain’s second Dark Sky Community


1 Brecon Beacons National Park International Dark Sky ReserveNational Park Visitor Centre Libanus, Brecon, Powys, LD3 8ER01874 623366www.beacons-npa.gov.uk/contact-us www.beacons-npa.gov.uk

2 Exmoor National ParkInternational Dark Sky ReserveDulverton National Park Centre7-9 Fore Street, Dulverton, TA22 9EX 01398 323841 [email protected] www.exmoor-nationalpark.gov.uk

3 Galloway Forest ParkInternational Dark Sky ParkGalloway Astronomy CentreA747, three miles east of Monreith01988 500594 [email protected] www.forestry.gov.uk/darkskygalloway

4 Isle of Coll International Dark Sky Communityc/o The Coll Hotel

Arinagour, Isle of Coll, PA78 6SZ01879 230334 [email protected] http://darkskies.visitcoll.co.uk

5 Northumberland National Park and Kielder Water and Forest Park International Dark Sky ParkOnce Brewed Visitor Centre Military Road, Bardon Mill, Hexham, NE47 7AN 01434 344396 [email protected] www.northumberlandnationalpark.org.uk

Kielder ObservatoryBlack Fell, Off Shilling Pot, Kielder, NE48 1EJ07805 638469 [email protected]

6 Isle of Sark International Dark Sky Communitywww.sark.co.uk Sark Tourist OffceThe Avenue, Sark Island, GY10 1SA01481 832345 [email protected]

Visiting the UK’s Dark Sky sites

70 dark sky sites april

“An International Dark

Sky Community is a

town, city, municipality,

or other legally organised community

that shows what the International Dark

Sky Association describes as ‘exceptional

dedication’ to preserving the night sky,”

explains amateur astronomer Olvin Smith,

who lives on the Inner Hebridean island

of Coll – since December 2013 the second

Dark Sky Community in Britain.

“It started around two years ago when

fellow astronomer Tony Oliver saw that Sark

had been awarded the status and thought

that we should get it as well,” Smith says.

“This led to a meeting which ended up

with a core group of four – myself, Tony,

hotel owner Julie Oliphant and guest house

owner Paula Smalley taking it forward. We

got in touch with the association, and had a

couple of phone calls with chief executive Bob

Parks, who talked us through the process.

Having purchased a Unihedron [sky quality]

meter, Smith completed a light survey

around the island. “On several sites I got

readings of 21.9 [magnitudes per square

arcsecond], which make our skies some of

the darkest in Europe,” he says. “Once we

had all the data, and with the help of a dark

skies consultant, Tony put together our

application, which was fnished last May.

“We had to alter some of the lights to

make them point straight down and get

commitment from some people to change

their outside lights to correct type,” Smith

notes. “We also needed to get the council

to endorse our lighting plan.”

It’s been very much a ‘ground up’

affair, Smith insists. “The community

has done all the work without any outside

funding; the money and work came

from the islanders.”

Isle of CollOLvIN SMITH

Amateur astronomer

CO

LL D

ARK

SK

Y G

RO

UP

1

2

3

4

5

6

Coll is Britain’s second Dark Sky Community

SP

EC

IAL

ED

ITIO

N

What are the deadliest animals?

How high are the tallest skyscrapers?

Which inventors were killed by their

own creations?

From the biggest and highest to the

strongest and hottest, the extremes of

life as we know it are revealed by The Big

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This 116-page special edition by

the makers of BBC Focus Magazine

explores science, technology, space, the

animal world, evolution, history and more

to explain how our planet works.

NEW FROM

The Earth is an amazing place: compare its longest rivers and highest mountains

+Calls to this number from a BT landline will cost no more than 5p per minute. Calls from mobiles and other providers may vary. Lines are open 8am-8pm weekdays & 9am-1pm Saturday.

*Prices including postage are: £9.49 for UK residents, £10.99 for Europe and £11.49 for Rest of World. All orders subject to availability. Please allow up to 21 days for delivery.

Journey to the final frontier, from the brightest stars to the biggest moons

Discover amazing feats of engineering that have left their mark on the planet

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What are the deadliest animals?

How high are the tallest skyscrapers?

Which inventors were killed by their

own creations?

From the biggest and highest to the

strongest and hottest, the extremes of

life as we know it are revealed by The Big

Book Of Top 10s.

This 116-page special edition by

the makers of BBC Focus Magazine

explores science, technology, space, the

animal world, evolution, history and more

to explain how our planet works.

NEW FROM

The Earth is an amazing place: compare its longest rivers and highest mountains

+Calls to this number from a BT landline will cost no more than 5p per minute. Calls from mobiles and other providers may vary. Lines are open 8am-8pm weekdays & 9am-1pm Saturday.

*Prices including postage are: £9.49 for UK residents, £10.99 for Europe and £11.49 for Rest of World. All orders subject to availability. Please allow up to 21 days for delivery.

Journey to the final frontier, from the brightest stars to the biggest moons

Discover amazing feats of engineering that have left their mark on the planet

ORDER TODAY ATwww.buysubscriptions.com/FOCUS10 0844 844 0388+

Or call our order hotline

Please quote

TOPHAX14

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+P&P*

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Two centuries after Fraunhofer discovered dark lines in the Sun’s spectrum, Will Gater looks at the next generation of spectroscopes

Every day, as Earth’s terminator sweeps

around the globe, the Sun sets in some

part of the world and the blue sky

deepens. On mountaintops and high

desert plateaus, domes open and motors whirr

as various kinds of astronomical machinery

housed in observatories heaves into life.

Like the coral polyps that emerge at night to

feed, the telescopes inside these observatories

are on the hunt for passing quarry. Yet they seek

something far more exotic than even the most

unusual plankton: photons of celestial light.

Photons that may have been travelling for billions

of years across unimaginably vast stretches of

space. Photons that, crucially, can reveal the

secrets of the objects they’ve come from.

As they peer out into space, the huge mirrors

of the world’s professional telescopes catch some

of these precious photons. Sensitive cameras can

record the light if need be, producing pictures

of stars, nebulae and galaxies that enable

astronomers to piece together the story of their

distant subjects. But to delve deeper into what

this light can tell them, astronomers must turn

unlockingThe SecreTS oF

>

thin

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Two centuries after Fraunhofer discovered dark lines in the Sun’s spectrum, Will Gater looks at the next generation of spectroscopes

Every day, as Earth’s terminator sweeps

around the globe, the Sun sets in some

part of the world and the blue sky

deepens. On mountaintops and high

desert plateaus, domes open and motors whirr

as various kinds of astronomical machinery

housed in observatories heaves into life.

Like the coral polyps that emerge at night to

feed, the telescopes inside these observatories

are on the hunt for passing quarry. Yet they seek

something far more exotic than even the most

unusual plankton: photons of celestial light.

Photons that may have been travelling for billions

of years across unimaginably vast stretches of

space. Photons that, crucially, can reveal the

secrets of the objects they’ve come from.

As they peer out into space, the huge mirrors

of the world’s professional telescopes catch some

of these precious photons. Sensitive cameras can

record the light if need be, producing pictures

of stars, nebulae and galaxies that enable

astronomers to piece together the story of their

distant subjects. But to delve deeper into what

this light can tell them, astronomers must turn

unlockingThe SecreTS oF

>

74


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to another, less celebrated, tool of astronomical

discovery – the spectrograph.

The realisation that light could harbour

information about celestial objects came thanks

to the work of the German glass-maker Joseph von

Fraunhofer. In 1814 he dispersed the Sun’s light

into a rainbow of colours – known as a spectrum

– discovering numerous dark absorption lines (see

‘The Science of Spectra’, right) that were later found

to betray the composition of our star. With the

subsequent development of spectroscopes to view –

and spectrographs to record – celestial spectra and

the lines they contained, astronomers had a means

to examine the make-up of stars.

The next generationEver since those early days, spectroscopy and

the spectrograph have been an integral part of

astronomical research, giving astronomers insights

into not just the composition of faraway bodies

but also their temperature, distance and even

movements. Now, two centuries after Fraunhofer’s

studies, astronomers are readying a new generation

of spectrographs to explore the Universe, the likes

of which have never been seen before.

Under the bright lights of the cavernous High Bay

clean room at NASA’s Goddard Space Flight Center

in Maryland, the James Webb Space Telescope is

slowly taking shape. Yellow scissor fences carefully

partition off areas of the immaculate, white-foored

room where instruments and other structures rest

on substantial support stands. High above, on an

enormous gantry, each of the telescope’s 18 primary

mirror segments sit protected within huge polished

metal containers. Gradually, the components

are being meticulously tested and, eventually,

integrated into the telescope’s skeleton, ahead of

its planned launch in 2018.

Sitting in its own corner of the Goddard clean

room, NIRSpec – the Near-Infrared Spectrograph

– is just one of the four instruments that will

fy on James Webb. As with all of the telescope’s

instruments, it will focus on observing the Universe

at infrared wavelengths. To understand why, you

only need to look at the work of James Webb’s

forebear, the Hubble Space Telescope.

Hubble has excelled at studying faraway galaxies

as well as extrasolar planets and how they form

within vast clouds of dust and gas. But to peer

Þ Lines in the Sun’s spectrum show which wavelengths of light have been absorbed by its atmosphere

Joseph von Fraunhofer, left, demonstrates his spectrocope in Munich in 1814

>

74


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, th

ink

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to another, less celebrated, tool of astronomical

discovery – the spectrograph.

The realisation that light could harbour

information about celestial objects came thanks

to the work of the German glass-maker Joseph von

Fraunhofer. In 1814 he dispersed the Sun’s light

into a rainbow of colours – known as a spectrum

– discovering numerous dark absorption lines (see

‘The Science of Spectra’, right) that were later found

to betray the composition of our star. With the

subsequent development of spectroscopes to view –

and spectrographs to record – celestial spectra and

the lines they contained, astronomers had a means

to examine the make-up of stars.

The next generationEver since those early days, spectroscopy and

the spectrograph have been an integral part of

astronomical research, giving astronomers insights

into not just the composition of faraway bodies

but also their temperature, distance and even

movements. Now, two centuries after Fraunhofer’s

studies, astronomers are readying a new generation

of spectrographs to explore the Universe, the likes

of which have never been seen before.

Under the bright lights of the cavernous High Bay

clean room at NASA’s Goddard Space Flight Center

in Maryland, the James Webb Space Telescope is

slowly taking shape. Yellow scissor fences carefully

partition off areas of the immaculate, white-foored

room where instruments and other structures rest

on substantial support stands. High above, on an

enormous gantry, each of the telescope’s 18 primary

mirror segments sit protected within huge polished

metal containers. Gradually, the components

are being meticulously tested and, eventually,

integrated into the telescope’s skeleton, ahead of

its planned launch in 2018.

Sitting in its own corner of the Goddard clean

room, NIRSpec – the Near-Infrared Spectrograph

– is just one of the four instruments that will

fy on James Webb. As with all of the telescope’s

instruments, it will focus on observing the Universe

at infrared wavelengths. To understand why, you

only need to look at the work of James Webb’s

forebear, the Hubble Space Telescope.

Hubble has excelled at studying faraway galaxies

as well as extrasolar planets and how they form

within vast clouds of dust and gas. But to peer

Þ Lines in the Sun’s spectrum show which wavelengths of light have been absorbed by its atmosphere

Joseph von Fraunhofer, left, demonstrates his spectrocope in Munich in 1814

>

stellar spectroscopy april 75


The science of spectraKey to understanding why spectroscopy is such a formidable tool for astronomers is knowing what creates the features of a spectrum. You can think of the lines in astronomical spectra as celestial fngerprints, in that they can help scientists work out what atoms and molecules created them.

These ‘fngerprints’ come in two forms, absorption lines and emission lines. Let’s look at absorption lines frst. Objects such as stars create what are known as continuum spectra. If we think about just the visible-light portion of the electromagnetic spectrum, a continuum spectrum looks like an unbroken rainbow of

colours from violet at one end to red at the other. Yet when we look at stars within this continuum we see dark lines, like those that Fraunhofer saw in the spectrum of the Sun. These are absorption lines. They’re made when photons of light passing through the star’s atmosphere interact with electrons in the gases there. These electrons can absorb the photons’ energy, removing certain wavelengths from the continuum. Which ones are removed depends on the atoms or molecules present. By identifying the dark lines in a spectrum astronomers can determine the composition of the star’s atmosphere.

In emission lines you see the opposite. For example, photons from a bright star may be causing a nearby nebula to glow. When this happens, the photons from the star give energy to, or ‘excite’, the electrons in the nebula’s gases. Those electrons will eventually settle down and they do this by releasing energy in the form of a photon of light. The wavelengths of the photons emitted are indicative of the atom or molecule that is glowing. If you could observe the light from the nebula with a spectroscope, you’d see a series of thin, bright lines of different colours – these are emission lines.

STARNEBULA

Star’s atmosphere

Hot bright stars

ABSORPTION LINES EMISSION LINES

further out into the Universe and deeper into

nebulae you need to see the cosmos at much longer

wavelengths, says NIRSpec instrument scientist

James Muzerolle. “Near-infrared and mid-infrared

observations allow us to penetrate the dusty

environments that are very important for studying

star and planet formation,” he says.

Using NIRSpec, astronomers will also be able to

study light from some of the most distant, and thus

earliest, galaxies. Light that has been stretched as it

travelled across the expanding Universe. “The light

that we’ll measure at our telescope will be light that

was originally mostly in the ultraviolet [section of

the spectrum] that’s been redshifted into the near-

infrared,” explains Muzerolle. “You have to be able

to look at longer wavelengths in the near-infrared

[region] in order to detect [the galaxies] at all.”

Like all spectrographs, NIRSpec will break

down the light of celestial objects into spectra Þ NIRSpec’s flter carousel sits in the centre of the device and holds eight light flters>



The science of spectraKey to understanding why spectroscopy is such a formidable tool for astronomers is knowing what creates the features of a spectrum. You can think of the lines in astronomical spectra as celestial fngerprints, in that they can help scientists work out what atoms and molecules created them.

These ‘fngerprints’ come in two forms, absorption lines and emission lines. Let’s look at absorption lines frst. Objects such as stars create what are known as continuum spectra. If we think about just the visible-light portion of the electromagnetic spectrum, a continuum spectrum looks like an unbroken rainbow of

colours from violet at one end to red at the other. Yet when we look at stars within this continuum we see dark lines, like those that Fraunhofer saw in the spectrum of the Sun. These are absorption lines. They’re made when photons of light passing through the star’s atmosphere interact with electrons in the gases there. These electrons can absorb the photons’ energy, removing certain wavelengths from the continuum. Which ones are removed depends on the atoms or molecules present. By identifying the dark lines in a spectrum astronomers can determine the composition of the star’s atmosphere.

In emission lines you see the opposite. For example, photons from a bright star may be causing a nearby nebula to glow. When this happens, the photons from the star give energy to, or ‘excite’, the electrons in the nebula’s gases. Those electrons will eventually settle down and they do this by releasing energy in the form of a photon of light. The wavelengths of the photons emitted are indicative of the atom or molecule that is glowing. If you could observe the light from the nebula with a spectroscope, you’d see a series of thin, bright lines of different colours – these are emission lines.

STARNEBULA

Star’s atmosphere

Hot bright stars

ABSORPTION LINES EMISSION LINES

further out into the Universe and deeper into

nebulae you need to see the cosmos at much longer

wavelengths, says NIRSpec instrument scientist

James Muzerolle. “Near-infrared and mid-infrared

observations allow us to penetrate the dusty

environments that are very important for studying

star and planet formation,” he says.

Using NIRSpec, astronomers will also be able to

study light from some of the most distant, and thus

earliest, galaxies. Light that has been stretched as it

travelled across the expanding Universe. “The light

that we’ll measure at our telescope will be light that

was originally mostly in the ultraviolet [section of

the spectrum] that’s been redshifted into the near-

infrared,” explains Muzerolle. “You have to be able

to look at longer wavelengths in the near-infrared

[region] in order to detect [the galaxies] at all.”

Like all spectrographs, NIRSpec will break

down the light of celestial objects into spectra Þ NIRSpec’s flter carousel sits in the centre of the device and holds eight light flters>

76


whose features, such as dark absorption lines, can

tell astronomers much about what they’re looking

at. But NIRSpec’s great strength will be its ability to

carry out what is known as multi-object spectroscopy.

“With a traditional spectrograph you have one slit

that, generally speaking, is only big enough to put

onto one object, like one star. You have to go one at

a time to build up a large

sample of spectroscopy of

many different stars,”

explains Muzerolle.

NIRSpec will be able to

capture the spectra of

around a hundred celestial

objects, such as stars or faint galaxies, in one shot.

It’s able to do this thanks to an advanced piece of

technology known as a micro-shutter array.

Shut out the light“Even on the ground there are not a lot of

instruments that have used this kind of

technology,” says Muzerolle. In essence, the micro-

shutter array’s role is to purposely block out large

parts of NIRSpec’s feld of view. Light from the

JWST’s 6.5m mirror will be fed into NIRSpec via a

complex system of optics. But before it reaches the

instrument’s grating, which spreads the light into

a spectrum, it will frst encounter the array. Here a

panel of roughly a quarter of a million microscopic

doors, or ‘shutters’, can be programmed to remain

either open or closed while the instrument is

making its observations. The result being that light

will only be let through from a select few parts

of the instrument’s feld of view – the parts that

contain the objects the

astronomers specifcally

want spectra of.

“For example if you

want to take spectroscopy

of stars in a cluster you

point the telescope at the

cluster and then open the shutters at the positions

of the stars that you’re interested in,” explains

Muzerolle. “All of the rest of the shutters [would

be] closed so that you don’t get any background or

other contaminating light getting through.”

The light going through the open shutters

from the chosen targets will then fall onto one of

NIRSpec’s gratings, which will produce spectra

that can be imaged by the instrument’s extremely

sensitive camera chips. This image, of up to a

hundred tiny infrared ‘rainbows’, will then be

beamed back to Earth where it can be analysed

by astronomers on the ground.

“NIRSpec will be able to capture the spectra of around a hundred

celestial objects in one shot”

Þ The JWST will see the Universe in infrared, allowing it to look back at the earliest galaxies

>

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asa

/Jpl

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si

76


whose features, such as dark absorption lines, can

tell astronomers much about what they’re looking

at. But NIRSpec’s great strength will be its ability to

carry out what is known as multi-object spectroscopy.

“With a traditional spectrograph you have one slit

that, generally speaking, is only big enough to put

onto one object, like one star. You have to go one at

a time to build up a large

sample of spectroscopy of

many different stars,”

explains Muzerolle.

NIRSpec will be able to

capture the spectra of

around a hundred celestial

objects, such as stars or faint galaxies, in one shot.

It’s able to do this thanks to an advanced piece of

technology known as a micro-shutter array.

Shut out the light“Even on the ground there are not a lot of

instruments that have used this kind of

technology,” says Muzerolle. In essence, the micro-

shutter array’s role is to purposely block out large

parts of NIRSpec’s feld of view. Light from the

JWST’s 6.5m mirror will be fed into NIRSpec via a

complex system of optics. But before it reaches the

instrument’s grating, which spreads the light into

a spectrum, it will frst encounter the array. Here a

panel of roughly a quarter of a million microscopic

doors, or ‘shutters’, can be programmed to remain

either open or closed while the instrument is

making its observations. The result being that light

will only be let through from a select few parts

of the instrument’s feld of view – the parts that

contain the objects the

astronomers specifcally

want spectra of.

“For example if you

want to take spectroscopy

of stars in a cluster you

point the telescope at the

cluster and then open the shutters at the positions

of the stars that you’re interested in,” explains

Muzerolle. “All of the rest of the shutters [would

be] closed so that you don’t get any background or

other contaminating light getting through.”

The light going through the open shutters

from the chosen targets will then fall onto one of

NIRSpec’s gratings, which will produce spectra

that can be imaged by the instrument’s extremely

sensitive camera chips. This image, of up to a

hundred tiny infrared ‘rainbows’, will then be

beamed back to Earth where it can be analysed

by astronomers on the ground.

“NIRSpec will be able to capture the spectra of around a hundred

celestial objects in one shot”

Þ The JWST will see the Universe in infrared, allowing it to look back at the earliest galaxies

>

>na

sa

, th

ink

sto

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, n

asa

/es

a,

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sa

/Jpl

-ca

ltec

h/m

ali

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pac

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ien

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syste

ms,

eso

/l.

ca

lça

da

, n

asa

/Jpl

-ca

ltec

h/s

si



The Cosmic Origins Spectrograph The Cosmic Origins Spectrograph (COS) sits inside the Hubble Space Telescope. It was ftted to the orbiting observatory in 2009, when Hubble was visited by astronauts on Space Shuttle Atlantis. As its name suggests, the instrument is used to explore how various objects in the Universe, including galaxies and stars, came into being. In particular, COS has been used to examine the large-scale network of galaxies and gas present in space, known as the ‘cosmic web’.

insTrumenTs of discoverya number of missions have used spectroscopy to deliver insights into the workings of the Universe

ChemCamNASA’s Curiosity rover certainly lives up to its original name – the Mars Science Laboratory. It is covered with cameras and scientifc instruments, including the ChemCam spectrometer. ChemCam works by zapping a target, such as an interesting rock, with a powerful laser. The plasma released is then analysed to see what the target is made of. The range of the laser is such that the instrument can study features that are 7m away from the rover.

HARPSThe High Accuracy Radial Velocity Planet Searcher (HARPS) is mounted on the ESO 3.6m Telescope at the La Silla Observatory in Chile. From this mountaintop site, with pristine skies, HARPS is used to hunt for planets orbiting around distant stars. By looking for tell-tale movements of the lines in the spectra of these faraway stars, scientists are able to use the instrument to infer the presence of extrasolar worlds.

VIMSThe Cassini mission to Saturn has been exploring the ringed planet and its moons since 2004. On board the spacecraft are cameras, spectrometers and other scientifc instruments that have given us incredible insights into this remarkable planetary system. The Visible and Infrared Mapping Spectrometer (VIMS) has studied the icy jets coming from Saturn’s moon Enceladus, the hydrocarbon lakes on the planet’s largest moon Titan and weather in the gas giant’s atmosphere.



The Cosmic Origins Spectrograph The Cosmic Origins Spectrograph (COS) sits inside the Hubble Space Telescope. It was ftted to the orbiting observatory in 2009, when Hubble was visited by astronauts on Space Shuttle Atlantis. As its name suggests, the instrument is used to explore how various objects in the Universe, including galaxies and stars, came into being. In particular, COS has been used to examine the large-scale network of galaxies and gas present in space, known as the ‘cosmic web’.

insTrumenTs of discoverya number of missions have used spectroscopy to deliver insights into the workings of the Universe

ChemCamNASA’s Curiosity rover certainly lives up to its original name – the Mars Science Laboratory. It is covered with cameras and scientifc instruments, including the ChemCam spectrometer. ChemCam works by zapping a target, such as an interesting rock, with a powerful laser. The plasma released is then analysed to see what the target is made of. The range of the laser is such that the instrument can study features that are 7m away from the rover.

HARPSThe High Accuracy Radial Velocity Planet Searcher (HARPS) is mounted on the ESO 3.6m Telescope at the La Silla Observatory in Chile. From this mountaintop site, with pristine skies, HARPS is used to hunt for planets orbiting around distant stars. By looking for tell-tale movements of the lines in the spectra of these faraway stars, scientists are able to use the instrument to infer the presence of extrasolar worlds.

VIMSThe Cassini mission to Saturn has been exploring the ringed planet and its moons since 2004. On board the spacecraft are cameras, spectrometers and other scientifc instruments that have given us incredible insights into this remarkable planetary system. The Visible and Infrared Mapping Spectrometer (VIMS) has studied the icy jets coming from Saturn’s moon Enceladus, the hydrocarbon lakes on the planet’s largest moon Titan and weather in the gas giant’s atmosphere.

78 stellar spectroscopy april


ABOUT THE WRITER

Will Gater is an astronomy writer and journalist. the author of several astronomy books, he regularly appears tV and radio. Find him on twitter: @willgater

In capturing spectra of many stars at once,

NIRSpec will allow astronomers to gather large

samples of data that should shine a light on the

processes at work in star and planet formation.

“From a statistical standpoint, this will really

advance the feld by a considerable amount,” says

Muzerolle. When the instrument surveys the most

distant realms of the Universe it should also tell us

more about how some of the frst galaxies were born

and how they evolved.

In doing so it will give

astronomers a glimpse

of the Universe as it was

“a few hundred million

years after the Big Bang”,

says Muzerolle. “We

hope that we’ll be able

to see many galaxies

that are in the process

of forming, of collecting their initial material,” he

adds. NIRSpec isn’t the only spectrograph that will

be operating on James Webb though.

A second pair of eyesMIRI, the Mid-Infrared Instrument, will study

many of the objects that NIRSpec will. But

because it observes in the longer wavelength,

mid-infrared region of the electromagnetic

spectrum it will also be able to examine some

phenomena that NIRSpec can’t. “With MIRI

we’ll be able to study a whole range of astronomical

objects from inside our own Solar System to

the furthest reaches of the observable Universe,”

says Sarah Kendrew, one of the astronomers who

worked on MIRI. “It is particularly sensitive to

colder, dustier environments, the sort that we

currently struggle to observe with the Hubble Space

Telescope. Discs of dust around newly formed stars,

for example, will be excellent targets for MIRI. As

those are the birthplaces of planets, that’s a

particularly exciting area of research.”

Spectrographs have

been at the very heart

of astronomy for two

centuries. And one can

only imagine the awe

with which Fraunhofer

might regard modern

instruments, like MIRI

and NIRSpec, if he could

see them in their clean

room today. Two hundred years ago his pioneering

work revolutionised our understanding of the

Universe. Now the legacy of that work is preparing

to launch into space to start a new, and equally

ground-breaking, revolution of its own.

“MIRI will be able to study a range of objects from inside our

own Solar System to the furthest reaches of the Universe”

Þ MIRI will be used to see what’s inside the dust clouds around newly formed stars

S

>

ala

my

78 stellar spectroscopy april


ABOUT THE WRITER

Will Gater is an astronomy writer and journalist. the author of several astronomy books, he regularly appears tV and radio. Find him on twitter: @willgater

In capturing spectra of many stars at once,

NIRSpec will allow astronomers to gather large

samples of data that should shine a light on the

processes at work in star and planet formation.

“From a statistical standpoint, this will really

advance the feld by a considerable amount,” says

Muzerolle. When the instrument surveys the most

distant realms of the Universe it should also tell us

more about how some of the frst galaxies were born

and how they evolved.

In doing so it will give

astronomers a glimpse

of the Universe as it was

“a few hundred million

years after the Big Bang”,

says Muzerolle. “We

hope that we’ll be able

to see many galaxies

that are in the process

of forming, of collecting their initial material,” he

adds. NIRSpec isn’t the only spectrograph that will

be operating on James Webb though.

A second pair of eyesMIRI, the Mid-Infrared Instrument, will study

many of the objects that NIRSpec will. But

because it observes in the longer wavelength,

mid-infrared region of the electromagnetic

spectrum it will also be able to examine some

phenomena that NIRSpec can’t. “With MIRI

we’ll be able to study a whole range of astronomical

objects from inside our own Solar System to

the furthest reaches of the observable Universe,”

says Sarah Kendrew, one of the astronomers who

worked on MIRI. “It is particularly sensitive to

colder, dustier environments, the sort that we

currently struggle to observe with the Hubble Space

Telescope. Discs of dust around newly formed stars,

for example, will be excellent targets for MIRI. As

those are the birthplaces of planets, that’s a

particularly exciting area of research.”

Spectrographs have

been at the very heart

of astronomy for two

centuries. And one can

only imagine the awe

with which Fraunhofer

might regard modern

instruments, like MIRI

and NIRSpec, if he could

see them in their clean

room today. Two hundred years ago his pioneering

work revolutionised our understanding of the

Universe. Now the legacy of that work is preparing

to launch into space to start a new, and equally

ground-breaking, revolution of its own.

“MIRI will be able to study a range of objects from inside our

own Solar System to the furthest reaches of the Universe”

Þ MIRI will be used to see what’s inside the dust clouds around newly formed stars

S

>

ala

my

*These extra items will be available with various issues in 2014 depending on subscription start date. After your fi rst 12 issues, you will then go on to pay £38.40 every 12 issues by Direct Debit,saving 20%. This offer is only open to new UK Direct Debit customers subscribing to Gardeners’ World Magazine. The closing date for this offer is April 30th 2014. You may cancel at any time and receive a full refund on any outstanding issues by contacting your bank or building society. Written confi rmation may also be required. Prices are discounted from the full UK subscription price and include P & P. Standard UK subscription price is £48, Europe and Republic of Ireland is £63.60 and Rest of the World is £80.40. Calling the 0844 848 9707 order number from a BT landline will cost no more than 5p per minute. Calls from mobiles and other providers may vary. Please note enquiry lines are open 9am-6pm.

SAVE 50% when you subscribe today!

Never miss an inspiring issue of

BBC Gardeners’ World Magazine.

Subscribe today by Direct Debit and

save 50% of the cover price, paying

just £24 for 12 issues. This great-value

subscription of er will bring you

practical, trustworthy and expert

advice to help you work wonders

over the coming months.Subscribe today!

Just £24 for 12 issues

I Exclusive subscriber-only of ers and invitations to events

I Extra discounts on plant of ers

I Quarterly newsletter full of gardening of ers and events

I Delivery direct to your door

I Your own subscriber edition with exclusive cover and content in every issue

PLUS When you subscribe, you’ll become a member

of the BBC Gardeners’ World Magazine Subscriber Club.

Enjoy many benef ts including:

Extras FREE with this yearÕs magazine*:

I 2-for-1 Gardens to Visit Card and Guide I Small Garden Handbook I 2015 BBC Gardeners’ World Magazine

calendar, and more…

To celebrate spring we are of ering a whole year’s worth

of gardening advice for only £24 – that’s just £2 per issue

A subscription to BBC Gardeners’ World Magazine will help you appreciate your garden in the day and the Sky at Night

2 EASY WAYS TO SUBSCRIBE

Visit www.buysubscriptions.com/gardenersworld/GWXSN414

Call 0844 848 9707 and quote code GWXSN414 (Lines open Mon to Fri 8am-8pm and Sat 9am-1pm)

*These extra items will be available with various issues in 2014 depending on subscription start date. After your fi rst 12 issues, you will then go on to pay £38.40 every 12 issues by Direct Debit,saving 20%. This offer is only open to new UK Direct Debit customers subscribing to Gardeners’ World Magazine. The closing date for this offer is April 30th 2014. You may cancel at any time and receive a full refund on any outstanding issues by contacting your bank or building society. Written confi rmation may also be required. Prices are discounted from the full UK subscription price and include P & P. Standard UK subscription price is £48, Europe and Republic of Ireland is £63.60 and Rest of the World is £80.40. Calling the 0844 848 9707 order number from a BT landline will cost no more than 5p per minute. Calls from mobiles and other providers may vary. Please note enquiry lines are open 9am-6pm.

SAVE 50% when you subscribe today!

Never miss an inspiring issue of

BBC Gardeners’ World Magazine.

Subscribe today by Direct Debit and

save 50% of the cover price, paying

just £24 for 12 issues. This great-value

subscription of er will bring you

practical, trustworthy and expert

advice to help you work wonders

over the coming months.Subscribe today!

Just £24 for 12 issues

I Exclusive subscriber-only of ers and invitations to events

I Extra discounts on plant of ers

I Quarterly newsletter full of gardening of ers and events

I Delivery direct to your door

I Your own subscriber edition with exclusive cover and content in every issue

PLUS When you subscribe, you’ll become a member

of the BBC Gardeners’ World Magazine Subscriber Club.

Enjoy many benef ts including:

Extras FREE with this yearÕs magazine*:

I 2-for-1 Gardens to Visit Card and Guide I Small Garden Handbook I 2015 BBC Gardeners’ World Magazine

calendar, and more…

To celebrate spring we are of ering a whole year’s worth

of gardening advice for only £24 – that’s just £2 per issue

A subscription to BBC Gardeners’ World Magazine will help you appreciate your garden in the day and the Sky at Night

2 EASY WAYS TO SUBSCRIBE

Visit www.buysubscriptions.com/gardenersworld/GWXSN414

Call 0844 848 9707 and quote code GWXSN414 (Lines open Mon to Fri 8am-8pm and Sat 9am-1pm)

Pete Lawrence reveals his secrets to creating a frst-class lunar mosaic – from capturing the raw data to completion

THE MOONmosaicing

The Moon is a fascinating object to

both observe and image. The ever-

changing shadows crossing the

lunar surface make each and every

Moon session unique and interesting.

At roughly 0.5º across, it is relatively easy to

photograph the entire lunar disc in one go with

a DSLR camera, but this won’t bring out any

intricate detail. A telescope ftted with a high

frame rate camera allows you to get closer,

especially at high magnifcation. This typically

results in an image that shows more detail but

covers a smaller area of the Moon.

If you want highly detailed images of the

entire lunar disc, you need to use a technique

known as ‘mosaicing’. This is the process of taking

a number of zoomed-in shots and joining them

together. The ultimate goal is to produce a high-

resolution image of the whole lunar disc. Over

the next few pages, we take you through all the

steps necessary to produce one from scratch.

ABOUT THE WRITER

Pete Lawrence is an expert imager. Each month, he tells us about a new lunar target in our Moonwatch column – fnd it in the Sky Guide.

If you’re inspired by Pete’s effort, or think you could do the better, why not enter 2014’s Astronomy Photographer of the Year competition? Among the seven categories and prizes being contested is ‘Our Solar System’, for which the judges are looking for images that show the best of our cosmic backyard. For full details on how to sign up, the rules and how to submit your images, visit the competition website. www.rmg.co.uk/astrophoto

Pete Lawrence reveals his secrets to creating a frst-class lunar mosaic – from capturing the raw data to completion

THE MOONmosaicing

The Moon is a fascinating object to

both observe and image. The ever-

changing shadows crossing the

lunar surface make each and every

Moon session unique and interesting.

At roughly 0.5º across, it is relatively easy to

photograph the entire lunar disc in one go with

a DSLR camera, but this won’t bring out any

intricate detail. A telescope ftted with a high

frame rate camera allows you to get closer,

especially at high magnifcation. This typically

results in an image that shows more detail but

covers a smaller area of the Moon.

If you want highly detailed images of the

entire lunar disc, you need to use a technique

known as ‘mosaicing’. This is the process of taking

a number of zoomed-in shots and joining them

together. The ultimate goal is to produce a high-

resolution image of the whole lunar disc. Over

the next few pages, we take you through all the

steps necessary to produce one from scratch.

ABOUT THE WRITER

Pete Lawrence is an expert imager. Each month, he tells us about a new lunar target in our Moonwatch column – fnd it in the Sky Guide.

If you’re inspired by Pete’s effort, or think you could do the better, why not enter 2014’s Astronomy Photographer of the Year competition? Among the seven categories and prizes being contested is ‘Our Solar System’, for which the judges are looking for images that show the best of our cosmic backyard. For full details on how to sign up, the rules and how to submit your images, visit the competition website. www.rmg.co.uk/astrophoto

The author’s own mosaic of the waxing gibbous Moon; it is made

up of a staggering 213 panes PEtE L

aw

rEn

cEThe author’s own mosaic of the

waxing gibbous Moon; it is made up of a staggering 213 panes P

EtE L

aw

rEn

cE

1skyatnightmagazine.com 2014

Before you can create a mosaic, you

need detailed pictures. a mono high frame

rate camera is really the best tool for the job,

allowing you to record a short video of each

‘pane’ (segment of the lunar surface) as an

aVI fle, the individual frames of which can

be stacked into a still image later. If your

camera doesn’t have an infrared-blocking

flter built-in, consider attaching an infrared-

pass flter. Doing so can reduce the effects

of poor seeing. alternatively, try a red flter.

Moving across the lunar surface in

overlapping panels is something that sounds

easy to do, but there are pitfalls. The higher PEtE

La

wrEn

cE x

4, stE

vE m

arsh

Þ Follow the surface horizontally; higher magnifcation increases the number of panes but the method stays the same

the magnifcation you use, for instance, the

easier it is to get lost and miss a bit out; this

is a common frustration when starting out.

It pays to be realistic in terms of image scale.

If you’re experimenting with mosaics for

the frst time, capture a small number of

panes to start with so you can get a feel of

what’s what. Image scale can be adjusted

using optical amplifers such as Barlow

lenses, but aim to keep your scope’s overall

focal ratio somewhere between f/15 and f/45.

only go higher if the seeing gets really good.

a driven, equatorially mounted scope is

ideal. check camera alignment by slewing

in right ascension and rotating the camera

so that features move parallel to the bottom

edge of the frame. finally, focus your setup.

An equatorial setup is the most useful mount for mosaicing

caPTURing THE MOONRemembering a few simple rules will help you to capture a lunar mosaic without any gaps

Start

Finish

overlap

over

lap

Area of Moon visible (pane)

þ High frame rate cameras are the

best choice for lunar mosaicing

Use the features at the bottom of the frst row of frames as a guide for lining up the next row

Use features at the leading edge of the frame as a guide for the next frame

1skyatnightmagazine.com 2014

Before you can create a mosaic, you

need detailed pictures. a mono high frame

rate camera is really the best tool for the job,

allowing you to record a short video of each

‘pane’ (segment of the lunar surface) as an

aVI fle, the individual frames of which can

be stacked into a still image later. If your

camera doesn’t have an infrared-blocking

flter built-in, consider attaching an infrared-

pass flter. Doing so can reduce the effects

of poor seeing. alternatively, try a red flter.

Moving across the lunar surface in

overlapping panels is something that sounds

easy to do, but there are pitfalls. The higher PEtE

La

wrEn

cE x

4,

stE

vE m

arsh

Þ Follow the surface horizontally; higher magnifcation increases the number of panes but the method stays the same

the magnifcation you use, for instance, the

easier it is to get lost and miss a bit out; this

is a common frustration when starting out.

It pays to be realistic in terms of image scale.

If you’re experimenting with mosaics for

the frst time, capture a small number of

panes to start with so you can get a feel of

what’s what. Image scale can be adjusted

using optical amplifers such as Barlow

lenses, but aim to keep your scope’s overall

focal ratio somewhere between f/15 and f/45.

only go higher if the seeing gets really good.

a driven, equatorially mounted scope is

ideal. check camera alignment by slewing

in right ascension and rotating the camera

so that features move parallel to the bottom

edge of the frame. finally, focus your setup.

An equatorial setup is the most useful mount for mosaicing

caPTURing THE MOONRemembering a few simple rules will help you to capture a lunar mosaic without any gaps

Start

Finish

overlap

over

lap

Area of Moon visible (pane)

þ High frame rate cameras are the

best choice for lunar mosaicing

Use the features at the bottom of the frst row of frames as a guide for lining up the next row

Use features at the leading edge of the frame as a guide for the next frame

2

making a lunar mosaic april 83


There are various ways to move across

the Moon, but imaging in horizontal

strips with lots of overlap is best. a good

overlap is typically 20-25 per cent. When

lining up your frst pane, make a note of

features close to the corners of the frame

and use these as guides when positioning

for the next one.

It’s good practice to image the strips in

the same direction, moving back to the

same starting side of the Moon between

strips. use features in the frst strip of panes

to make sure your vertical adjustment

gives plenty of overlap. a rough sketch of

the feature in each frame can help. If you

lose track, wind back to the last place you

know you defnitely imaged. It’s better to

risk duplication than a gap!

The nexT sTep is to process each aVI

fle to produce one still image, ready

for assembly into the fnal mosaic.

for a large mosaic containing many

individual panes this can be a daunting

and tedious task, but there are ways

to speed things up.

The frst processing step is to analyse,

register and stack the frames in each

aVI fle. There are various good (not to

mention, free) computer programs that

can do this for you automatically, among

them registax, autostakkert! and

avistack. for this project we’ll be using

avistack to take care of the bulk of the

processing and registax to perform

wavelet sharpening on the results.

The analysis step determines the

quality of each still frame and then

ranks them in order of how good they

are. a user-set quality threshold then

determines how many of the frames

are used. The frames that are above

the threshold are ‘registered’ (aligned)

to one another. These are then

‘stacked’ (averaged) to produce

a fnal image.

The higher the quality

threshold, the fewer frames

will ultimately go into the

stack. This will result in the

sharpest output, but with less

frames to average, noise is

more noticeable. set the quality

threshold lower and there will

be more frames to average,

resulting in a smoother, less

noisy result. however, using

lower quality frames reduces

overall image sharpness.

It’s a good idea to perform

a number of test runs using

avistack if you’re not familiar

with the program. There are a

lot of parameters and settings

that can be confgured; these are

shown in a separate window and can

be viewed by expanding the tree list.

Double clicking on a parameter section,

for example ‘frame selection’, will bring

point your scope at the brightest part of

the Moon and adjust the camera’s gain and

exposure so peak saturation is around 90

per cent. you should be able to leave this

alone. of course, you can adjust the exposure

levels for each frame if you want, but this

is more time consuming and requires

greater effort when it comes to stitching

your panes together; the advantage is less

noise in dark regions and extra navigational

detail when crossing seemingly featureless

areas such as the lunar seas.

What you will need to do during a long

mosaicing run is refocus often. This is

essential to prevent defocusing caused by

temperature variations. a 12V camping

hairdryer is also invaluable for removing

moisture from dewed-up optics during

long runs. Two fnal tips: mosaic captures

typically take up lots of computer hard

disk space, so make sure you have plenty

free; and plan ahead to make sure the

Moon doesn’t disappear behind by a

neighbouring tree or rooftop part-way

through your imaging session.

Þ You’ll need fewer panes to complete your mosaic at f/15, but at f/45 you’ll get more detail

Single pane at f/15

Single pane at f/45Þ Lining up your panes with a generous overlap will lessen the chances of missing a piece

PRocessing THE MOONNow that you’ve captured your panes as movie fles it’s time to turn them into high-resolution images

up a control window allowing you to

adjust the settings for that section. you

can toggle between automatic and

manual processing by clicking on

Þ Quality analysis determines which frames will give you the best results for each pane

>

2

making a lunar mosaic april 83


There are various ways to move across

the Moon, but imaging in horizontal

strips with lots of overlap is best. a good

overlap is typically 20-25 per cent. When

lining up your frst pane, make a note of

features close to the corners of the frame

and use these as guides when positioning

for the next one.

It’s good practice to image the strips in

the same direction, moving back to the

same starting side of the Moon between

strips. use features in the frst strip of panes

to make sure your vertical adjustment

gives plenty of overlap. a rough sketch of

the feature in each frame can help. If you

lose track, wind back to the last place you

know you defnitely imaged. It’s better to

risk duplication than a gap!

The nexT sTep is to process each aVI

fle to produce one still image, ready

for assembly into the fnal mosaic.

for a large mosaic containing many

individual panes this can be a daunting

and tedious task, but there are ways

to speed things up.

The frst processing step is to analyse,

register and stack the frames in each

aVI fle. There are various good (not to

mention, free) computer programs that

can do this for you automatically, among

them registax, autostakkert! and

avistack. for this project we’ll be using

avistack to take care of the bulk of the

processing and registax to perform

wavelet sharpening on the results.

The analysis step determines the

quality of each still frame and then

ranks them in order of how good they

are. a user-set quality threshold then

determines how many of the frames

are used. The frames that are above

the threshold are ‘registered’ (aligned)

to one another. These are then

‘stacked’ (averaged) to produce

a fnal image.

The higher the quality

threshold, the fewer frames

will ultimately go into the

stack. This will result in the

sharpest output, but with less

frames to average, noise is

more noticeable. set the quality

threshold lower and there will

be more frames to average,

resulting in a smoother, less

noisy result. however, using

lower quality frames reduces

overall image sharpness.

It’s a good idea to perform

a number of test runs using

avistack if you’re not familiar

with the program. There are a

lot of parameters and settings

that can be confgured; these are

shown in a separate window and can

be viewed by expanding the tree list.

Double clicking on a parameter section,

for example ‘frame selection’, will bring

point your scope at the brightest part of

the Moon and adjust the camera’s gain and

exposure so peak saturation is around 90

per cent. you should be able to leave this

alone. of course, you can adjust the exposure

levels for each frame if you want, but this

is more time consuming and requires

greater effort when it comes to stitching

your panes together; the advantage is less

noise in dark regions and extra navigational

detail when crossing seemingly featureless

areas such as the lunar seas.

What you will need to do during a long

mosaicing run is refocus often. This is

essential to prevent defocusing caused by

temperature variations. a 12V camping

hairdryer is also invaluable for removing

moisture from dewed-up optics during

long runs. Two fnal tips: mosaic captures

typically take up lots of computer hard

disk space, so make sure you have plenty

free; and plan ahead to make sure the

Moon doesn’t disappear behind by a

neighbouring tree or rooftop part-way

through your imaging session.

Þ You’ll need fewer panes to complete your mosaic at f/15, but at f/45 you’ll get more detail

Single pane at f/15

Single pane at f/45Þ Lining up your panes with a generous overlap will lessen the chances of missing a piece

PRocessing THE MOONNow that you’ve captured your panes as movie fles it’s time to turn them into high-resolution images

up a control window allowing you to

adjust the settings for that section. you

can toggle between automatic and

manual processing by clicking on

Þ Quality analysis determines which frames will give you the best results for each pane

>

84


PEtE L

aw

rEn

cE x

10

STEP 3That’s your frst processed fle complete. The settings for this fle will be automatically used for the batch processing run. Click ‘Add movies’ and select all of the fles to be processed, then click ‘Open’. Finally, click ‘Batch processing’ and let the program run through each fle in turn, saving the results according to the settings you chose in the save stacked image box in the previous step.

the gear wheel icon below the

section header. setting the toggle

to ‘automatic processing’ lets avistack

make decisions for you, which can be

useful if you’re not initially sure what

you’re doing.

avistack has a great batch-processing

mode that can work on large numbers

of aVI fles unattended. The end result

is a single distilled image for each aVI

capture. Various output formats are

available but we recommend pnG as

this is a lossless format that many

editing programs and fle viewers can

easily display. other lossless fles can also

be used, but how easy they are to view

and manipulate may vary. avoid lossy

formats such as JpeG.

following the step-by-step guide below,

the initial process delivers results with

no sharpening. To the eye these will look

blurred, so to address this we’ll apply the

excellent wavelet sharpening function

within registax.

sharpening lunar images is something

that needs to be done with great care.

once you start to apply sharpening to an

image, it’s easy to get carried away and

push it just that little bit too far.

If in doubt, it’s a good idea to leave

the image up on your computer screen

and walk away from it for a while. When

you come back, your initial reaction

will be a good indicator as to whether

you’ve taken things too far. If you’re

creating your mosaic at low magnifcation,

a gentle tweak on the frst slider is all that’s

normally required.

STEP 1Load a single AVI into AviStack for processing. If you’re technically minded, choose ‘Settings’, ‘Processing’, ‘All manual’ from the main window menu. If not, select ‘All automatic’. Expand the ‘Save stacked image’ section and make sure ‘Manual processing’ is set; click on “Automatic processing” if shown. Expand ‘Post processing’ and select ‘Manual processing’. The four options below this should be deselected, as shown above.

STEP 4Once you have all the AviStack-processed PNG results, copy them all to a new folder, named something like ‘Wavelet-sharpened’. These are the fles we’ll edit in RegiStax; leaving the originals untouched means you can rework them at a later date – say if new software or more advanced techniques become available. Once you have your fnal results, the originals can be discarded if you need the disk space.

STEP 5Run RegiStax and click ‘Select’. Change ‘Files of type’ to match the format of the processed images (in our example, PNG). Load the frst image. With the Wavelet tab selected, click on the preview buttons to the right of the sliders to see which details will change. Use the slider that shows the fnest detail that isn’t just noise grain. Adjust the slider to sharpen the image to taste.

STEP 6Wavelet sharpen all of the images, saving each when done. Next, load the frst image into a layer-based editing program such as Photoshop or GIMP and crop off any unwanted edge artefacts. Estimate and adjust the canvas size so that it will hold all of the panes; don’t worry too much if you get the size wrong as it can be adjusted later. Select a black background for the new canvas area before you do this.

STEP 2Click on ‘Process fle’. When the ‘Save stacked image’ window appears – see right – select PNG as the fle type and defne the save folder. Make sure ‘Save parameters’ is ticked before you click on ‘Save’. Press ‘Cancel’ when the ‘Post processing’ window appears. Test the suitability of the result for wavelet sharpening – see step 5. If it is not, repeat and adjust parameter settings during a manual run using the help options to assist.

Add Movies(fle open)

Batch processing

Þ AVIs can be batch processed manually or automatically

prOcEssiNg – sTEp by sTEp

>

84


PEtE L

aw

rEn

cE x

10

STEP 3That’s your frst processed fle complete. The settings for this fle will be automatically used for the batch processing run. Click ‘Add movies’ and select all of the fles to be processed, then click ‘Open’. Finally, click ‘Batch processing’ and let the program run through each fle in turn, saving the results according to the settings you chose in the save stacked image box in the previous step.

the gear wheel icon below the

section header. setting the toggle

to ‘automatic processing’ lets avistack

make decisions for you, which can be

useful if you’re not initially sure what

you’re doing.

avistack has a great batch-processing

mode that can work on large numbers

of aVI fles unattended. The end result

is a single distilled image for each aVI

capture. Various output formats are

available but we recommend pnG as

this is a lossless format that many

editing programs and fle viewers can

easily display. other lossless fles can also

be used, but how easy they are to view

and manipulate may vary. avoid lossy

formats such as JpeG.

following the step-by-step guide below,

the initial process delivers results with

no sharpening. To the eye these will look

blurred, so to address this we’ll apply the

excellent wavelet sharpening function

within registax.

sharpening lunar images is something

that needs to be done with great care.

once you start to apply sharpening to an

image, it’s easy to get carried away and

push it just that little bit too far.

If in doubt, it’s a good idea to leave

the image up on your computer screen

and walk away from it for a while. When

you come back, your initial reaction

will be a good indicator as to whether

you’ve taken things too far. If you’re

creating your mosaic at low magnifcation,

a gentle tweak on the frst slider is all that’s

normally required.

STEP 1Load a single AVI into AviStack for processing. If you’re technically minded, choose ‘Settings’, ‘Processing’, ‘All manual’ from the main window menu. If not, select ‘All automatic’. Expand the ‘Save stacked image’ section and make sure ‘Manual processing’ is set; click on “Automatic processing” if shown. Expand ‘Post processing’ and select ‘Manual processing’. The four options below this should be deselected, as shown above.

STEP 4Once you have all the AviStack-processed PNG results, copy them all to a new folder, named something like ‘Wavelet-sharpened’. These are the fles we’ll edit in RegiStax; leaving the originals untouched means you can rework them at a later date – say if new software or more advanced techniques become available. Once you have your fnal results, the originals can be discarded if you need the disk space.

STEP 5Run RegiStax and click ‘Select’. Change ‘Files of type’ to match the format of the processed images (in our example, PNG). Load the frst image. With the Wavelet tab selected, click on the preview buttons to the right of the sliders to see which details will change. Use the slider that shows the fnest detail that isn’t just noise grain. Adjust the slider to sharpen the image to taste.

STEP 6Wavelet sharpen all of the images, saving each when done. Next, load the frst image into a layer-based editing program such as Photoshop or GIMP and crop off any unwanted edge artefacts. Estimate and adjust the canvas size so that it will hold all of the panes; don’t worry too much if you get the size wrong as it can be adjusted later. Select a black background for the new canvas area before you do this.

STEP 2Click on ‘Process fle’. When the ‘Save stacked image’ window appears – see right – select PNG as the fle type and defne the save folder. Make sure ‘Save parameters’ is ticked before you click on ‘Save’. Press ‘Cancel’ when the ‘Post processing’ window appears. Test the suitability of the result for wavelet sharpening – see step 5. If it is not, repeat and adjust parameter settings during a manual run using the help options to assist.

Add Movies(fle open)

Batch processing

Þ AVIs can be batch processed manually or automatically

prOcEssiNg – sTEp by sTEp

>

3making a lunar mosaic april 85


The excITInG parT of mosaicing is

building the fnal image. There are free

programs that can do this automatically,

including Microsoft’s excellent Image

composite editor (Ice). Building the

mosaic manually is a more time-consuming

process, but ultimately a rewarding

experience. Doing it yourself can also help

to avoid the errors that sometimes occur

when using automated programs.

If you followed our step-by-step guide

on the previous page, your base image

will contain a single fnished pane and

your canvas will be of suffcient size to

take the rest.

Load the next frame in the sequence

and draw a selection box slightly smaller

than the frame edge within it. apply a

5-10 pixel feather to the selection.

copy the selection and paste it into

the base image. use the arrow keys to

nudge the pane into alignment with

the lower image. Toggling the visibility

of the nudged layer on and off will help

you to line it up accurately.

small variations in tone between the

pasted and base images can normally be

dealt with by gently tweaking the curves

tool – you should apply the adjustment

to the centre of the curve. for larger

variations, raise or drop the brightness

of the image frst to get it closer to where

you want it, then use the curves tool to

carry out fne adjustments.

The feathered edges of the pasted

image pane should make any straight

edges hard to see. If some are still obvious,

set the eraser tool to 10 per cent strength

and gently rub it over any visible joins;

this should hide them.

for very large mosaics that stretch

your computer’s memory, assemble a

batch of panes and then save the layered

image to a fle called ‘mosaic-001’. flatten

the image and continue loading with the

next set of frames. When you get to a

similar stage as before, save as ‘mosaic-002’

and fatten. repeat until the whole mosaic

is complete. This technique means you

can go back and address any major

problems found at the end.

When done, fatten the image and save

to a fle name of your choice. a gentle

tweak of brightness or contrast, or a small

adjustment using the Levels and curves

tools, can help to fnish off your masterpiece.

It takes a bit of work to build such a mosaic

manually but once it’s done, the feeling of

satisfaction will be immense; that is unless

you’ve missed a bit of course!

sTiTching THE MOONAll the hard work you’ve put in up to this point is about to pay off with the best part, assembling the mosaic

Þ Align your panes by zooming in and nudging them into place with the arrow keys

Þ You may need to adjust brightness and contrast to blend adjacent panes together

Whether a full disc or a crescent, a lunar mosaic is one of the most rewarding

images you can produce

S

3making a lunar mosaic april 85


The excITInG parT of mosaicing is

building the fnal image. There are free

programs that can do this automatically,

including Microsoft’s excellent Image

composite editor (Ice). Building the

mosaic manually is a more time-consuming

process, but ultimately a rewarding

experience. Doing it yourself can also help

to avoid the errors that sometimes occur

when using automated programs.

If you followed our step-by-step guide

on the previous page, your base image

will contain a single fnished pane and

your canvas will be of suffcient size to

take the rest.

Load the next frame in the sequence

and draw a selection box slightly smaller

than the frame edge within it. apply a

5-10 pixel feather to the selection.

copy the selection and paste it into

the base image. use the arrow keys to

nudge the pane into alignment with

the lower image. Toggling the visibility

of the nudged layer on and off will help

you to line it up accurately.

small variations in tone between the

pasted and base images can normally be

dealt with by gently tweaking the curves

tool – you should apply the adjustment

to the centre of the curve. for larger

variations, raise or drop the brightness

of the image frst to get it closer to where

you want it, then use the curves tool to

carry out fne adjustments.

The feathered edges of the pasted

image pane should make any straight

edges hard to see. If some are still obvious,

set the eraser tool to 10 per cent strength

and gently rub it over any visible joins;

this should hide them.

for very large mosaics that stretch

your computer’s memory, assemble a

batch of panes and then save the layered

image to a fle called ‘mosaic-001’. flatten

the image and continue loading with the

next set of frames. When you get to a

similar stage as before, save as ‘mosaic-002’

and fatten. repeat until the whole mosaic

is complete. This technique means you

can go back and address any major

problems found at the end.

When done, fatten the image and save

to a fle name of your choice. a gentle

tweak of brightness or contrast, or a small

adjustment using the Levels and curves

tools, can help to fnish off your masterpiece.

It takes a bit of work to build such a mosaic

manually but once it’s done, the feeling of

satisfaction will be immense; that is unless

you’ve missed a bit of course!

sTiTching THE MOONAll the hard work you’ve put in up to this point is about to pay off with the best part, assembling the mosaic

Þ Align your panes by zooming in and nudging them into place with the arrow keys

Þ You may need to adjust brightness and contrast to blend adjacent panes together

Whether a full disc or a crescent, a lunar mosaic is one of the most rewarding

images you can produce

S

UK


It is quite easy to become daunted by the vast array

of equipment that is available to today’s amateur

astronomers. Different makes, different models, different

sizes and optical arrangements – if you’re new to the

hobby, how do you make sense of all these details and fnd the

telescope that will show you the Universe?

The answer lies in buying from a specialist retailer –

somewhere that really knows what they’re talking about. Like

the retailers in this guide, they’ll have the practical knowledge

that will guide you towards the scope that won’t end up

gathering dust in a cupboard.

Today there are over 1,000 models of telescope to choose

from – refractors and refectors, Dobsonians and Newtonians,

Schmidt- and Maksutov-Cassegrains. And just as important as

the telescope is the mount it sits on; but do you go for equatorial

or altazimuth, manual or Go-To? And what about accessories

like eyepieces and fnderscopes?

That’s certainly a lot to consider before making a decision,

but a specialist retailer will help you make that decision, taking

important considerations like portability, construction and price

into account.

So if you need friendly, face-to-face advice and excellent

aftersales service, free from biased opinions, specialist

telescope retailers are the place to go for a helping hand

through the technical literature and tables of fgures. They’ll

help you fnd a scope that combines quality and convenience at

a price that’s right.

Find the right one for you: buy your

telescope from a specialist retailer

Retailer Guide

UK


It is quite easy to become daunted by the vast array

of equipment that is available to today’s amateur

astronomers. Different makes, different models, different

sizes and optical arrangements – if you’re new to the

hobby, how do you make sense of all these details and fnd the

telescope that will show you the Universe?

The answer lies in buying from a specialist retailer –

somewhere that really knows what they’re talking about. Like

the retailers in this guide, they’ll have the practical knowledge

that will guide you towards the scope that won’t end up

gathering dust in a cupboard.

Today there are over 1,000 models of telescope to choose

from – refractors and refectors, Dobsonians and Newtonians,

Schmidt- and Maksutov-Cassegrains. And just as important as

the telescope is the mount it sits on; but do you go for equatorial

or altazimuth, manual or Go-To? And what about accessories

like eyepieces and fnderscopes?

That’s certainly a lot to consider before making a decision,

but a specialist retailer will help you make that decision, taking

important considerations like portability, construction and price

into account.

So if you need friendly, face-to-face advice and excellent

aftersales service, free from biased opinions, specialist

telescope retailers are the place to go for a helping hand

through the technical literature and tables of fgures. They’ll

help you fnd a scope that combines quality and convenience at

a price that’s right.

Find the right one for you: buy your

telescope from a specialist retailer

Retailer Guide


Telescope House

01342 837610www.telescopehouse.com

[email protected]

Founded in 1785, Telescope House has been responsible for supplying many well-known Astronomers with telescopes and equipment. The late Sir Patrick Moore bought the majority of his telescopes from the company, including his very frst instrument. With a friendly showroom in Surrey, a number one ranked retail website and a service centre with fully qualifed staff, the company offers equipment from manufacturers such as Meade, Revelation, Coronado, Bresser, Skywatcher, Orion USA, TeleVue, Vixen and Explore Scientifc. Whether it’s advice on your frst telescope, to setting up advanced Astrophotography systems, the staff at Telescope House have a wealth of experience and instant access to the right stock to back it up.

TRinG AsTRonomy cenTRe

01442 822997 www.tringastro.co.uk

[email protected]

At Tring Astronomy Centre we know that choosing the right equipment can be a minefeld, but we strongly believe that seeing telescopes in the fesh and talking to an expert in a relaxed environment can really help. That’s why we have a coffee machine, a fully stocked bicuit barrel, and 45+ telescopes on display. As well as representing leading brands such as Celestron, Sky-Watcher, Baader Planetarium, Altair Astro, Vixen, Opticron, AstroTrac, iOptron, Lunt, Starlight Instruments, ZW Optical and many more we also offer a hire service so you can even try before you buy! So what are you waiting for? Visit or contact Tring Astronomy Centre and lets talk Astronomy!

sHeRwoodsEstablished for over 60 years, we at Sherwoods are one of the Midlands leading suppliers of astronomical telescopes, binoculars and accessories. Through our website and showroom we are able to supply optics from some of the world’s leading optical manufacturers including Celestron, Skywatcher and Meade at some of the lowest prices in the UK. We offer a full mail-order service including next day delivery on many items held in stock.

01527 857500www.binocularhouse.com

[email protected]

GReen wiTcHGreen Witch is one of the UK’s leading suppliers of telescopes, binoculars and accessories for astronomy. Founded by former members of the Royal Greenwich Observatory in 1998, Green Witch is dedicated to helping you choose and use the equipment that is right for you.

We also carry an extensive range of telescopes and binoculars for nature and leisure, which you are welcome to try before you buy. Whether you visit our showrooms or buy online you can be sure of excellent service.

01924 477719 - Birstall, west yorks 01767 677025 - Gransden,

Beds & cambswww.green-witch.com

The Widescreen cenTre

02079 352580 www.widescreen-centre.co.uk

[email protected]

The Widescreen Centre is London’s Astronomy Showroom, located in Sherlock Holmes territory off Baker Street in the heart of Marylebone - a family owned and run business since starting out in1971. Our experienced and highly knowledgeable staff will offer you quality, choice, expertise and service - see Celestron, Sky-Watcher, Meade, Orion, Tele Vue, APM, Takahashi and much, much more besides says Simon Bennett, Widescreen’s MD and lifelong amateur astronomer, “If the correct equipment is purchased it will give a lifetime’s enjoyment. This is our mission. We will never sell you anything you don’t need” Watch out for Widescreen at Star Parties and exhibitions throughout the UK.

AsTronomiAAtronomia is the award-winning home of the biggest range of telescopes and binoculars on display in the South of England. With over 50 telescopes and even more binoculars, Astronomia brings you the widest choice from respected brands such as Celestron, Sky-Watcher, Meade, Vixen and more. Visit our store in the High Street, Dorking or check out the website. Take advantage of our full-price trade-ins on all telescopes – if you upgrade within 12 months, you don’t lose a penny!

01306 640714www.astronomia.co.uk

[email protected]


Telescope House

01342 837610www.telescopehouse.com

[email protected]

Founded in 1785, Telescope House has been responsible for supplying many well-known Astronomers with telescopes and equipment. The late Sir Patrick Moore bought the majority of his telescopes from the company, including his very frst instrument. With a friendly showroom in Surrey, a number one ranked retail website and a service centre with fully qualifed staff, the company offers equipment from manufacturers such as Meade, Revelation, Coronado, Bresser, Skywatcher, Orion USA, TeleVue, Vixen and Explore Scientifc. Whether it’s advice on your frst telescope, to setting up advanced Astrophotography systems, the staff at Telescope House have a wealth of experience and instant access to the right stock to back it up.

TRinG AsTRonomy cenTRe

01442 822997 www.tringastro.co.uk

[email protected]

At Tring Astronomy Centre we know that choosing the right equipment can be a minefeld, but we strongly believe that seeing telescopes in the fesh and talking to an expert in a relaxed environment can really help. That’s why we have a coffee machine, a fully stocked bicuit barrel, and 45+ telescopes on display. As well as representing leading brands such as Celestron, Sky-Watcher, Baader Planetarium, Altair Astro, Vixen, Opticron, AstroTrac, iOptron, Lunt, Starlight Instruments, ZW Optical and many more we also offer a hire service so you can even try before you buy! So what are you waiting for? Visit or contact Tring Astronomy Centre and lets talk Astronomy!

sHeRwoodsEstablished for over 60 years, we at Sherwoods are one of the Midlands leading suppliers of astronomical telescopes, binoculars and accessories. Through our website and showroom we are able to supply optics from some of the world’s leading optical manufacturers including Celestron, Skywatcher and Meade at some of the lowest prices in the UK. We offer a full mail-order service including next day delivery on many items held in stock.

01527 857500www.binocularhouse.com

[email protected]

GReen wiTcHGreen Witch is one of the UK’s leading suppliers of telescopes, binoculars and accessories for astronomy. Founded by former members of the Royal Greenwich Observatory in 1998, Green Witch is dedicated to helping you choose and use the equipment that is right for you.

We also carry an extensive range of telescopes and binoculars for nature and leisure, which you are welcome to try before you buy. Whether you visit our showrooms or buy online you can be sure of excellent service.

01924 477719 - Birstall, west yorks 01767 677025 - Gransden,

Beds & cambswww.green-witch.com

The Widescreen cenTre

02079 352580 www.widescreen-centre.co.uk

[email protected]

The Widescreen Centre is London’s Astronomy Showroom, located in Sherlock Holmes territory off Baker Street in the heart of Marylebone - a family owned and run business since starting out in1971. Our experienced and highly knowledgeable staff will offer you quality, choice, expertise and service - see Celestron, Sky-Watcher, Meade, Orion, Tele Vue, APM, Takahashi and much, much more besides says Simon Bennett, Widescreen’s MD and lifelong amateur astronomer, “If the correct equipment is purchased it will give a lifetime’s enjoyment. This is our mission. We will never sell you anything you don’t need” Watch out for Widescreen at Star Parties and exhibitions throughout the UK.

AsTronomiAAtronomia is the award-winning home of the biggest range of telescopes and binoculars on display in the South of England. With over 50 telescopes and even more binoculars, Astronomia brings you the widest choice from respected brands such as Celestron, Sky-Watcher, Meade, Vixen and more. Visit our store in the High Street, Dorking or check out the website. Take advantage of our full-price trade-ins on all telescopes – if you upgrade within 12 months, you don’t lose a penny!

01306 640714www.astronomia.co.uk

[email protected]


The guide

MA

RK G

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/SC

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, N

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The Local Group

Contents

With

Elizabeth Pearson

The guide

88An introduction to the Milky Way’s

neighbouring galaxies

The Milky Way is one of the mainstays in this galactic family

Brush up on your astronomy prowess with our team of expertsSkills

88

SKILLS

The Milky Way is not alone in

the Universe. Our Galaxy

and its neighbouring spiral, the

Andromeda Galaxy, are locked

together by gravity. Caught along with

them are a host of 30-50 smaller galaxies,

among them M33 in Triangulum and the

How to

90Get steadier binocular views with a pair of

stabilising techniques

Sketching

93Discover how to sketch Mars, which

reaches opposition this month

Scope doctor

95Steve Richards answers your

astro equipment queries

Magellanic Clouds. Together, they make

up the Local Group.

The term ‘Local Group’ was introduced

by Edwin Hubble in 1936 while he was

measuring the distances to extragalactic

objects. Hubble realised that several of the

objects he had catalogued were so close to

the Milky Way that they must be affected

by its gravitational pull. By that time it

was already known that most galaxies

are found in either groups or their larger

cousins, clusters, and so Hubble suggested

that these objects were all part of our

Galaxy’s own group.

The Local Group of galaxies only contains three spirals, our own

Milky Way, M31 and M33

The Milky Way

The Andromeda Galaxy, M31

The Triangulum Galaxy, M33


The guide

MA

RK G

ARL

ICK

/SC

IEN

CE

PHO

TO L

IBR

ARY

, TH

INK

STO

CK

x 3

, N

OA

O/A

UR

A/N

SF

The Local Group

Contents

With

Elizabeth Pearson

The guide

88An introduction to the Milky Way’s

neighbouring galaxies

The Milky Way is one of the mainstays in this galactic family

Brush up on your astronomy prowess with our team of expertsSkills

88

SKILLS

The Milky Way is not alone in

the Universe. Our Galaxy

and its neighbouring spiral, the

Andromeda Galaxy, are locked

together by gravity. Caught along with

them are a host of 30-50 smaller galaxies,

among them M33 in Triangulum and the

How to

90Get steadier binocular views with a pair of

stabilising techniques

Sketching

93Discover how to sketch Mars, which

reaches opposition this month

Scope doctor

95Steve Richards answers your

astro equipment queries

Magellanic Clouds. Together, they make

up the Local Group.

The term ‘Local Group’ was introduced

by Edwin Hubble in 1936 while he was

measuring the distances to extragalactic

objects. Hubble realised that several of the

objects he had catalogued were so close to

the Milky Way that they must be affected

by its gravitational pull. By that time it

was already known that most galaxies

are found in either groups or their larger

cousins, clusters, and so Hubble suggested

that these objects were all part of our

Galaxy’s own group.

The Local Group of galaxies only contains three spirals, our own

Milky Way, M31 and M33

The Milky Way

The Andromeda Galaxy, M31

The Triangulum Galaxy, M33

Observing the LocaL Group

skiLLs APRIL 89


Over the years astronomers have found

more nearby dwarf galaxies, upping the

number in the Local Group to several dozen.

The exact population is still a matter of

some contention: in order to be part of the

group, a galaxy needs to be gravitationally

bound to the other members, something

that can be hard to work out.

Gravitational graspMost of the galaxies in the Local Group

are satellites of either the Milky Way or the

Andromeda Galaxy. There are a few

others that are not, such as the Aquarius

and Phoenix Dwarf Galaxies, but we know

that they must be part of the group as they

are too close not to be affected by the

combined gravity of the two large spirals.

The problem comes for galaxies that are

on the edge of the group’s gravitational

infuence. Calculating distances on these

huge scales is extremely diffcult using the

usual techniques of resolving individual

stars visually and calculating redshift with

spectroscopy. In several cases a galaxy has

at frst appeared to be part of the Local

Group, only for a more precise distance

measurement to place it in a nearby group;

this happened with irregular galaxy

UGCA 86. Once proposed to be part of the

Local Group, recent studies have placed

it in the IC 342/Maffei Group, an adjacent

congregation of galaxies within 10 million

lightyears of our own.

Telling which galaxies are part of the Local

Group will be a lot easier in a few billion

years, however, as they are slowly being

pulled together. The largest two members

of the group, Andromeda and the Milky Way,

are heading towards a massive collision in

about four billion years. While this will be

the most spectacular crash these two spirals

have encountered, it won’t be the frst. The

remains of dwarf galaxies that have been

subsumed by Andromeda can be seen in

our galactic companion, while a structure

called the Virgo Stellar Stream is believed

to be what’s left of a dwarf that is currently

merging with the Milky Way. When the

largest members of the Local Group merge,

they will form a massive elliptical galaxy.

What will happen to the smaller

galaxies is a little more uncertain. Some

will get consumed in the merger, others

will continue to orbit as satellite galaxies

and some may be thrown out of the

system entirely.

Elizabeth Pearson is BBC Sky at Night Magazine’s staff writer

ThE AndroMEdA GALAXY, M31

Equipment: naked eye, binoculars, telescopeConstellation: AndromedaAt mag. +3.5, M31 is the brightest galaxy visible from the northern hemisphere; also look out for its satellite galaxies above and below it, designated M32 and M110 – you’ll need at least binoculars for these.

A few objects in the Local Group are prime targets for observing and imaging. That said, the light from these galaxies is spread out and

diffuse, meaning they can be a challenge to fnd and picking out detail is very tricky. As with most deep-sky objects, it’s critical to

observe from a very dark site – from good locations you may be able to see some of these four with the naked eye.

ThE MILKY WAY

Equipment: naked eyeThe Milky Way appears as a band of stars across the sky as we look out through the plane of our Galaxy. The exact position of the band on the sky changes throughout the year, showing us different parts of the Galaxy.

ThE LArGE And SMALL MAGELLAnIC CLoudS (LMC And SMC)

Equipment: naked eye, binoculars, telescopeConstellation: dorado/Mensa (LMC); Tucana (SMC)This duo are only visible from the southern hemisphere. The LMC is an irregular galaxy, though a strong bar-like structure near the centre suggests it may once have been a spiral; the SMC is an irregular dwarf.

ThE TrIAnGuLuM GALAXY, M33

Equipment: Binoculars, telescopeConstellation: TriangulumIn April, the mag. +5.7 Triangulum Galaxy will appear low on the horizon in the early hours of the morning. It is most easily spotted with binoculars due to its low surface brightness.

S

Observing the LocaL Group

skiLLs APRIL 89


Over the years astronomers have found

more nearby dwarf galaxies, upping the

number in the Local Group to several dozen.

The exact population is still a matter of

some contention: in order to be part of the

group, a galaxy needs to be gravitationally

bound to the other members, something

that can be hard to work out.

Gravitational graspMost of the galaxies in the Local Group

are satellites of either the Milky Way or the

Andromeda Galaxy. There are a few

others that are not, such as the Aquarius

and Phoenix Dwarf Galaxies, but we know

that they must be part of the group as they

are too close not to be affected by the

combined gravity of the two large spirals.

The problem comes for galaxies that are

on the edge of the group’s gravitational

infuence. Calculating distances on these

huge scales is extremely diffcult using the

usual techniques of resolving individual

stars visually and calculating redshift with

spectroscopy. In several cases a galaxy has

at frst appeared to be part of the Local

Group, only for a more precise distance

measurement to place it in a nearby group;

this happened with irregular galaxy

UGCA 86. Once proposed to be part of the

Local Group, recent studies have placed

it in the IC 342/Maffei Group, an adjacent

congregation of galaxies within 10 million

lightyears of our own.

Telling which galaxies are part of the Local

Group will be a lot easier in a few billion

years, however, as they are slowly being

pulled together. The largest two members

of the group, Andromeda and the Milky Way,

are heading towards a massive collision in

about four billion years. While this will be

the most spectacular crash these two spirals

have encountered, it won’t be the frst. The

remains of dwarf galaxies that have been

subsumed by Andromeda can be seen in

our galactic companion, while a structure

called the Virgo Stellar Stream is believed

to be what’s left of a dwarf that is currently

merging with the Milky Way. When the

largest members of the Local Group merge,

they will form a massive elliptical galaxy.

What will happen to the smaller

galaxies is a little more uncertain. Some

will get consumed in the merger, others

will continue to orbit as satellite galaxies

and some may be thrown out of the

system entirely.

Elizabeth Pearson is BBC Sky at Night Magazine’s staff writer

ThE AndroMEdA GALAXY, M31

Equipment: naked eye, binoculars, telescopeConstellation: AndromedaAt mag. +3.5, M31 is the brightest galaxy visible from the northern hemisphere; also look out for its satellite galaxies above and below it, designated M32 and M110 – you’ll need at least binoculars for these.

A few objects in the Local Group are prime targets for observing and imaging. That said, the light from these galaxies is spread out and

diffuse, meaning they can be a challenge to fnd and picking out detail is very tricky. As with most deep-sky objects, it’s critical to

observe from a very dark site – from good locations you may be able to see some of these four with the naked eye.

ThE MILKY WAY

Equipment: naked eyeThe Milky Way appears as a band of stars across the sky as we look out through the plane of our Galaxy. The exact position of the band on the sky changes throughout the year, showing us different parts of the Galaxy.

ThE LArGE And SMALL MAGELLAnIC CLoudS (LMC And SMC)

Equipment: naked eye, binoculars, telescopeConstellation: dorado/Mensa (LMC); Tucana (SMC)This duo are only visible from the southern hemisphere. The LMC is an irregular galaxy, though a strong bar-like structure near the centre suggests it may once have been a spiral; the SMC is an irregular dwarf.

ThE TrIAnGuLuM GALAXY, M33

Equipment: Binoculars, telescopeConstellation: TriangulumIn April, the mag. +5.7 Triangulum Galaxy will appear low on the horizon in the early hours of the morning. It is most easily spotted with binoculars due to its low surface brightness.

S

90

SKILLS

The ‘grab and go’ nature of

small or medium binoculars

makes them very attractive

astronomical instruments.

Sooner or later, however, you will fnd that

you need to steady them a bit more in

order to make a critical observation.

One solution is to mount them, but a

mount immediately compromises their

portability and adds a layer of complexity.

You can, however, get steadier views

simply by changing the way you hold your

binoculars, which is what we are going

to explain this month.

Most of us instinctively hold Porro-

prism binoculars by the prism housings

and roof-prism binoculars about midway

along their length. This is tolerable for

terrestrial targets, but can quickly become

tiring when you are observing objects at

How to

Two techniques to help you split tricky double stars in no time

all

pic

tu

res: steph

en

to

nk

in

high altitudes. In order to improve things,

we need to apply some ergonomics.

Let’s assume you hold your binoculars

as described previously. When looking

through them horizontally, all the weight

is borne by your arms, which are cantilevered

out in front of you; the strain is mostly taken

by the deltoid muscles in your shoulder.

As you observe higher targets, your

forearm becomes more horizontal and

your triceps take more of the strain.

Additionally, when you observe objects at

high altitude your arms are much higher

than your heart, reducing the blood fow

to your arm muscles. This means they are

more likely to tire and start shaking. What

we need is a way of transferring the strain.

One way to do this is called the

‘triangular arm brace’, in which you

transfer some of the weight to your head


Get steadier binocular viewsWith Stephen Tonkin

and neck: as you lean further back to

observe higher targets, more and more of

the weight of the binoculars rests on your

head and less is borne by your arms,

making them less liable to shake. And this

is not the only beneft.

As any structural engineer will tell you,

the triangle is the simplest and most stable

mechanical structure. By holding your

binoculars in this position, you create two

triangles with your arms – these triangles

share a common side comprised of your head

and neck. The result is an immediately

noticeable improvement in stability. This

improvement is even more marked if you

take up a position where your head is also

supported, such as lying on a sunlounger.

If the binoculars have a suffciently long

strap, we can steady the view even more by

using a second technique similar that used

Even heavy binoculars can be held steady if your arms

aren’t taking the weight

90

SKILLS

The ‘grab and go’ nature of

small or medium binoculars

makes them very attractive

astronomical instruments.

Sooner or later, however, you will fnd that

you need to steady them a bit more in

order to make a critical observation.

One solution is to mount them, but a

mount immediately compromises their

portability and adds a layer of complexity.

You can, however, get steadier views

simply by changing the way you hold your

binoculars, which is what we are going

to explain this month.

Most of us instinctively hold Porro-

prism binoculars by the prism housings

and roof-prism binoculars about midway

along their length. This is tolerable for

terrestrial targets, but can quickly become

tiring when you are observing objects at

How to

Two techniques to help you split tricky double stars in no time

all

pic

tu

res:

steph

en

to

nk

in

high altitudes. In order to improve things,

we need to apply some ergonomics.

Let’s assume you hold your binoculars

as described previously. When looking

through them horizontally, all the weight

is borne by your arms, which are cantilevered

out in front of you; the strain is mostly taken

by the deltoid muscles in your shoulder.

As you observe higher targets, your

forearm becomes more horizontal and

your triceps take more of the strain.

Additionally, when you observe objects at

high altitude your arms are much higher

than your heart, reducing the blood fow

to your arm muscles. This means they are

more likely to tire and start shaking. What

we need is a way of transferring the strain.

One way to do this is called the

‘triangular arm brace’, in which you

transfer some of the weight to your head


Get steadier binocular viewsWith Stephen Tonkin

and neck: as you lean further back to

observe higher targets, more and more of

the weight of the binoculars rests on your

head and less is borne by your arms,

making them less liable to shake. And this

is not the only beneft.

As any structural engineer will tell you,

the triangle is the simplest and most stable

mechanical structure. By holding your

binoculars in this position, you create two

triangles with your arms – these triangles

share a common side comprised of your head

and neck. The result is an immediately

noticeable improvement in stability. This

improvement is even more marked if you

take up a position where your head is also

supported, such as lying on a sunlounger.

If the binoculars have a suffciently long

strap, we can steady the view even more by

using a second technique similar that used

Even heavy binoculars can be held steady if your arms

aren’t taking the weight

SKILLS april 91

STEP 1To fnd the correct position for your hands, cup them and hold them to your face so that the top knuckle of your thumb rests securely in the indent of your eye socket; the lower bone of your thumb should rest comfortably on your cheekbone.

STEP 2With the same cupped-hand position, hold the prism housings of the binoculars with your third and fourth fngers. Your forefnger will rest lightly on the eyepiece barrel and your middle fnger on the eyepiece bridge. Your palms will take the weight of the binoculars.

STEP 3Raise the binoculars to your eyes and re-settle your thumbs into their original positions resting on your cheekbones. If you have centre-focus binoculars, use your middle or ring fnger to adjust the focus wheel. If you have individual eyepiece focusing, use your forefngers.

STEP 4For the ultra-stable rife sling hold, you may need a longer strap. Cut a 1.7m length of nylon webbing and attach it to the strap lugs of your binoculars. Secure the strap with the 3-bar buckles, with the free ends trapped against the buckles.

STEP 5Hold the binoculars in front of you so the strap is looped down and, one at a time, put your arms through the strap and adjust its position so that it comes to just above your elbows. Hold the binoculars the same way as you did before.

STEP 6Raise the binoculars to your eyes as before and tension the strap by pushing your elbows apart. You should feel the binoculars pushing down on your hands and the whole ‘system’ of arms, head and straps becoming very rigid.


by marksmen to steady a rife. For this

reason, we call it the ‘rife sling’ method.

It works by creating tension between your

arms and the binoculars; the tension reduces

the ability of the binoculars to shake.

Armed and ready?This technique can be slightly awkward

until you get used to it, but get it right

and it is quite comfortable. The rife sling

method doesn’t quite have the stability of

mounted binoculars, but it’s not a long way

off for a pair of 10x50s. You should certainly

fnd that double stars that used to be tricky

to split suddenly seem much easier.

Even on larger binoculars that shouldn’t

really be hand-held – 15x70s for example

– the difference between the rife sling

approach and the normal way of holding

them is quite marked. Not only will you

fnd that more detail becomes visible in

large ‘fuzzy blobs’ like the Orion Nebula

and the Andromeda Galaxy, but also some

clusters will resolve more easily and seem

to have more stars. It can also help

distinguish between stars and those very

small objects that look stellar at low

magnifcation, such as active galaxy M77

in Cetus or the Ring Nebula, M57, in Lyra.

An added bonus to the improved

stability is that holding your binoculars

like this also has the advantage of

considerably reducing arm fatigue, so your

binocular observing sessions can become

longer and much more productive.

Stephen Tonkin writes our Binocular tour each month – fnd it in the Sky Guide

S

STEP-BY-STEP GUIDETOOLS AND

MATERIALSif you need a new strap for the ‘rife sling’ method

Finish

use a soldering iron to heat seal cut ends to prevent them fraying.

Materials

approximately 1.7m of nylon webbing to suit the strap-lugs on your binoculars, which are usually about 8mm wide, and a pair of 3-bar slide buckles to ft the webbing; you may be able to reuse the ones on your existing strap.

tools

scissors, craft knife or hot cutter, tape measure, ruler.

SKILLS april 91

STEP 1To fnd the correct position for your hands, cup them and hold them to your face so that the top knuckle of your thumb rests securely in the indent of your eye socket; the lower bone of your thumb should rest comfortably on your cheekbone.

STEP 2With the same cupped-hand position, hold the prism housings of the binoculars with your third and fourth fngers. Your forefnger will rest lightly on the eyepiece barrel and your middle fnger on the eyepiece bridge. Your palms will take the weight of the binoculars.

STEP 3Raise the binoculars to your eyes and re-settle your thumbs into their original positions resting on your cheekbones. If you have centre-focus binoculars, use your middle or ring fnger to adjust the focus wheel. If you have individual eyepiece focusing, use your forefngers.

STEP 4For the ultra-stable rife sling hold, you may need a longer strap. Cut a 1.7m length of nylon webbing and attach it to the strap lugs of your binoculars. Secure the strap with the 3-bar buckles, with the free ends trapped against the buckles.

STEP 5Hold the binoculars in front of you so the strap is looped down and, one at a time, put your arms through the strap and adjust its position so that it comes to just above your elbows. Hold the binoculars the same way as you did before.

STEP 6Raise the binoculars to your eyes as before and tension the strap by pushing your elbows apart. You should feel the binoculars pushing down on your hands and the whole ‘system’ of arms, head and straps becoming very rigid.


by marksmen to steady a rife. For this

reason, we call it the ‘rife sling’ method.

It works by creating tension between your

arms and the binoculars; the tension reduces

the ability of the binoculars to shake.

Armed and ready?This technique can be slightly awkward

until you get used to it, but get it right

and it is quite comfortable. The rife sling

method doesn’t quite have the stability of

mounted binoculars, but it’s not a long way

off for a pair of 10x50s. You should certainly

fnd that double stars that used to be tricky

to split suddenly seem much easier.

Even on larger binoculars that shouldn’t

really be hand-held – 15x70s for example

– the difference between the rife sling

approach and the normal way of holding

them is quite marked. Not only will you

fnd that more detail becomes visible in

large ‘fuzzy blobs’ like the Orion Nebula

and the Andromeda Galaxy, but also some

clusters will resolve more easily and seem

to have more stars. It can also help

distinguish between stars and those very

small objects that look stellar at low

magnifcation, such as active galaxy M77

in Cetus or the Ring Nebula, M57, in Lyra.

An added bonus to the improved

stability is that holding your binoculars

like this also has the advantage of

considerably reducing arm fatigue, so your

binocular observing sessions can become

longer and much more productive.

Stephen Tonkin writes our Binocular tour each month – fnd it in the Sky Guide

S

STEP-BY-STEP GUIDETOOLS AND

MATERIALSif you need a new strap for the ‘rife sling’ method

Finish

use a soldering iron to heat seal cut ends to prevent them fraying.

Materials

approximately 1.7m of nylon webbing to suit the strap-lugs on your binoculars, which are usually about 8mm wide, and a pair of 3-bar slide buckles to ft the webbing; you may be able to reuse the ones on your existing strap.

tools

scissors, craft knife or hot cutter, tape measure, ruler.

The Great Courses®, Unit A, Sovereign Business Park,

Brenda Road, Hartlepool, TS25 1NN. Terms and conditions

apply. See www.thegreatcourses.co.uk for details.

For 24 years, The Great Courses has brought the

world’s foremost educators to millions who want to

go deeper into the subjects that matter most. No

exams. No homework. Just a world of knowledge

available anytime, anywhere. Download or stream

to your laptop or PC, or use our free mobile apps

for iPad, iPhone, or Android. Nearly 500 courses

available at www.thegreatcourses.co.uk.

LIM

ITED TIME OFFE

R

55%off

O

RDER BY 18 M

AY

Black Holes ExplainedTaught by Professor Alex FilippenkoUNIVERSITY OF CALIFORNIA, BERKELEY

LECTURE TITLES

1. A General Introduction to Black Holes

2. The Violent Deaths of Massive Stars

3. Gamma-Ray Bursts—The Birth of Black Holes

4. Searching for Stellar-Mass Black Holes

5. Monster of the Milky Way and Other Galaxies

6. Quasars—Feasting Supermassive Black Holes

7. Gravitational Waves—Ripples in Space-Time

8. The Wildest Ride in the Universe

9. Shortcuts through the Universe and Beyond?

10. Stephen Hawking and Black Hole Evaporation

11. Black Holes and the Holographic Universe

12. Black Holes and the Large Hadron Collider

Black Holes ExplainedCourse no. 1841 | 12 lectures (30 minutes/lecture)

SAVE £18

DVD £29.99 NOW £11.99+£2.99 Postage and Packing

Priority Code: 96520

Make Sense of Black HolesBlack holes. They are one of the most exotic, mind-boggling, and profound subjects in astrophysics. Not only are they at the heart of some of the most intriguing phenomena in the cosmos, they’re the gateway to fundamental and cutting-edge concepts like general relativity and wormholes.

Nearly everyone has heard of black holes, but few people outside of complex scientific fields understand their true nature and their implications for our universe. Black Holes Explained finally makes this awe-inspiring cosmological subject accessible, with 12 lavishly illustrated lectures delivered by distinguished astronomer and award-winning professor Alex Filippenko. As he presents the actual science behind these amazing objects, you’ll make sense of Einstein rings, photon spheres, event horizons, and other concepts central to the study of black holes. Like its subject matter, this course is intriguing, eye-opening, and essential to your knowledge of how the universe works.

Of er expires 18/05/14

0800 298 9796WWW.THEGREATCOURSES.CO.UK/3SAN

The Great Courses®, Unit A, Sovereign Business Park,

Brenda Road, Hartlepool, TS25 1NN. Terms and conditions

apply. See www.thegreatcourses.co.uk for details.

For 24 years, The Great Courses has brought the

world’s foremost educators to millions who want to

go deeper into the subjects that matter most. No

exams. No homework. Just a world of knowledge

available anytime, anywhere. Download or stream

to your laptop or PC, or use our free mobile apps

for iPad, iPhone, or Android. Nearly 500 courses

available at www.thegreatcourses.co.uk.

LIM

ITED TIME OFFE

R

55%off

O

RDER BY 18 M

AY

Black Holes ExplainedTaught by Professor Alex FilippenkoUNIVERSITY OF CALIFORNIA, BERKELEY

LECTURE TITLES

1. A General Introduction to Black Holes

2. The Violent Deaths of Massive Stars

3. Gamma-Ray Bursts—The Birth of Black Holes

4. Searching for Stellar-Mass Black Holes

5. Monster of the Milky Way and Other Galaxies

6. Quasars—Feasting Supermassive Black Holes

7. Gravitational Waves—Ripples in Space-Time

8. The Wildest Ride in the Universe

9. Shortcuts through the Universe and Beyond?

10. Stephen Hawking and Black Hole Evaporation

11. Black Holes and the Holographic Universe

12. Black Holes and the Large Hadron Collider

Black Holes ExplainedCourse no. 1841 | 12 lectures (30 minutes/lecture)

SAVE £18

DVD £29.99 NOW £11.99+£2.99 Postage and Packing

Priority Code: 96520

Make Sense of Black HolesBlack holes. They are one of the most exotic, mind-boggling, and profound subjects in astrophysics. Not only are they at the heart of some of the most intriguing phenomena in the cosmos, they’re the gateway to fundamental and cutting-edge concepts like general relativity and wormholes.

Nearly everyone has heard of black holes, but few people outside of complex scientific fields understand their true nature and their implications for our universe. Black Holes Explained finally makes this awe-inspiring cosmological subject accessible, with 12 lavishly illustrated lectures delivered by distinguished astronomer and award-winning professor Alex Filippenko. As he presents the actual science behind these amazing objects, you’ll make sense of Einstein rings, photon spheres, event horizons, and other concepts central to the study of black holes. Like its subject matter, this course is intriguing, eye-opening, and essential to your knowledge of how the universe works.

Of er expires 18/05/14

0800 298 9796WWW.THEGREATCOURSES.CO.UK/3SAN

SKILLS APRIL 93

Sketching

all

pic

tu

res: c

aro

l la

ko

mia

k


MarsWith Carol Lakomiak

Like all of the naked-eye

planets in our Solar System,

Mars has been known to

mankind since ancient times

– Egyptian astronomers knew of its

retrograde motion by 1534 BC. When

Galileo viewed it through his telescope

over 3,000 years later, we fnally had a

closer look at Mars and we’ve been

studying it ever since.

This month, Mars’s opposition

occurs at 20:57 UT on the 8th; the planet

makes its closest approach to Earth, at a

distance of 92,386,484km, on the 14th at

12:54 UT. Mars’s size and magnitude will

fuctuate during the month, but not

enough to affect your choice of sketching

dates. Different features will come into

view though, so what you see might not

be the same as what’s shown here.

Mars is shown here the way it appears

to the naked-eye at culmination: north is

up and surface features rotate from left to

right (from the following limb towards

the preceding limb). Different telescopes

present different views though, so be sure

to mark your sketch with ‘N’ or ‘S’ for

north or south and ‘F’ or ‘P’ for following

or preceding). Following and preceding

are used instead of east and west to avoid

confusion, because when Mars is viewed

from the UK, its eastern limb faces

towards the western horizon.

Colour flters are useful for viewing

Mars. Casual observers often use a few of

them to increase contrast and enhance

clouds or dust storms. Advanced Mars

observers use a wider variety of flters to

help them detect details of the features

they’re studying. If you don’t have any

flters, don’t worry – just take your time

and sketch what you see.

Usually we include everything in the

eyepiece’s view when sketching, but use

your entire circle to represent Mars – this

way, you’ll be able to ft in all the details

you see. If you want your sketch to look

more like what you see in the eyepiece,

blacken the background sky. Do this with

a 9B pencil, black permanent marker or a

photo-editing program.

Carol Lakomiak is BBC Sky at Night Magazine’s sketching expert

Step 1

Make a swatch of B graphite on a small piece of paper. Then use your fngertip to evenly smudge the graphite over your entire sketching circle. Next, use the ‘fat’ side of the pencil’s graphite to lightly and evenly shade any dark features you see.

Name: Mars

type of object: Planet

coNSteLLatIoN: Virgo

Ra: 13h 22m to 12h 43m

dec: –05° 51’ to –02° 57’

equIpmeNt:

6-inch refector (or larger); B pencil; blending stump; soft and hard art erasers

beSt tIme to SKetch:

1-30 April, 11pm-2am BST (10pm-1am UT)

fIeLd of VIew ShowN:

15 arcminutes; 400x magnifcation

Step 2

Soften the dark features with a blending stump (small, circular motions work best). To complete the shading process, you’ll need to darken some areas. Do this by rubbing the blending stump on the graphite swatch, and using it like a pencil to bring out the darker areas.

Step 3

Indicate Mars’s bright areas by removing the background shading. For bright areas with a diffuse edge, round the tip of a soft eraser and ‘dab’ the graphite away. For bright areas with a distinct edge, cut the end of a hard eraser so it is fat and use it to ‘carve’ the graphite away.

Need TO KNOW

SKILLS

North polar cap

N

P

Mare Acidalium

Arabia

Eden

Sinus Meridiani Sinus

Sabaeus

Syrtis Major

Hellas

AeriaMoab

Utopia

Mare Tyrrhenum

Iapygia Viridis

N

P

N

P

SKILLS APRIL 93

Sketching

all

pic

tu

res:

ca

ro

l la

ko

mia

k


MarsWith Carol Lakomiak

Like all of the naked-eye

planets in our Solar System,

Mars has been known to

mankind since ancient times

– Egyptian astronomers knew of its

retrograde motion by 1534 BC. When

Galileo viewed it through his telescope

over 3,000 years later, we fnally had a

closer look at Mars and we’ve been

studying it ever since.

This month, Mars’s opposition

occurs at 20:57 UT on the 8th; the planet

makes its closest approach to Earth, at a

distance of 92,386,484km, on the 14th at

12:54 UT. Mars’s size and magnitude will

fuctuate during the month, but not

enough to affect your choice of sketching

dates. Different features will come into

view though, so what you see might not

be the same as what’s shown here.

Mars is shown here the way it appears

to the naked-eye at culmination: north is

up and surface features rotate from left to

right (from the following limb towards

the preceding limb). Different telescopes

present different views though, so be sure

to mark your sketch with ‘N’ or ‘S’ for

north or south and ‘F’ or ‘P’ for following

or preceding). Following and preceding

are used instead of east and west to avoid

confusion, because when Mars is viewed

from the UK, its eastern limb faces

towards the western horizon.

Colour flters are useful for viewing

Mars. Casual observers often use a few of

them to increase contrast and enhance

clouds or dust storms. Advanced Mars

observers use a wider variety of flters to

help them detect details of the features

they’re studying. If you don’t have any

flters, don’t worry – just take your time

and sketch what you see.

Usually we include everything in the

eyepiece’s view when sketching, but use

your entire circle to represent Mars – this

way, you’ll be able to ft in all the details

you see. If you want your sketch to look

more like what you see in the eyepiece,

blacken the background sky. Do this with

a 9B pencil, black permanent marker or a

photo-editing program.

Carol Lakomiak is BBC Sky at Night Magazine’s sketching expert

Step 1

Make a swatch of B graphite on a small piece of paper. Then use your fngertip to evenly smudge the graphite over your entire sketching circle. Next, use the ‘fat’ side of the pencil’s graphite to lightly and evenly shade any dark features you see.

Name: Mars

type of object: Planet

coNSteLLatIoN: Virgo

Ra: 13h 22m to 12h 43m

dec: –05° 51’ to –02° 57’

equIpmeNt:

6-inch refector (or larger); B pencil; blending stump; soft and hard art erasers

beSt tIme to SKetch:

1-30 April, 11pm-2am BST (10pm-1am UT)

fIeLd of VIew ShowN:

15 arcminutes; 400x magnifcation

Step 2

Soften the dark features with a blending stump (small, circular motions work best). To complete the shading process, you’ll need to darken some areas. Do this by rubbing the blending stump on the graphite swatch, and using it like a pencil to bring out the darker areas.

Step 3

Indicate Mars’s bright areas by removing the background shading. For bright areas with a diffuse edge, round the tip of a soft eraser and ‘dab’ the graphite away. For bright areas with a distinct edge, cut the end of a hard eraser so it is fat and use it to ‘carve’ the graphite away.

Need TO KNOW

SKILLS

North polar cap

N

P

Mare Acidalium

Arabia

Eden

Sinus Meridiani Sinus

Sabaeus

Syrtis Major

Hellas

AeriaMoab

Utopia

Mare Tyrrhenum

Iapygia Viridis

N

P

N

P

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HD 8x42 ......£69.99HD 8x56 ......£99.99HD 7x50 ......£79.99HD 10x50 ....£79.99

HUGE RANGE of eyepieces and accessories

102 EDtelescope outftwith 2” SWA eyepice,

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Eyepieces & AccessoriesEYEPIECES/ACCESSORIES

Plossl 5mm (1.25”) ................................................................. £14.99 Plossl 10mm (1.25”) .............................................................. £14.99 Plossl 15mm (1.25”) .............................................................. £14.99 Plossl 20mm (1.25”) .............................................................. £14.99 Plossl 25mm (1.25”) .............................................................. £17.99 Plossl 30mm (1.25”) .............................................................. £17.99 Plossl 40mm (1.25”) ............................................................. £19.99 Super Wide angle 10mm (1.25”) ....................................... £39.99 Super Wide angle 20mm (1.25”) ....................................... £44.99 FF 8mm (1.25”) ....................................................................... £49.99 FF 12mm (1.25”) .................................................................... £49.99 FF 19mm (1.25”) .................................................................... £49.99 FF 27mm (1.25”) .................................................................... £49.99 SWA 26mm (2”) ..................................................................... £79.99 SWA 32mm (2”) ..................................................................... £79.99 SWA 38mm (2”) ..................................................................... £79.99 SWA82 8.8mm (1.25”) ...................................................... £129.99 SWA82 14mm (1.25”) ....................................................... £149.99 SWA82 24mm (2”) ............................................................. £199.99

HD 12x60 ....£89.99HD 15x70 ....£99.99HD 20x80 .£149.99HD 20x80T .£249.99

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Visionary HD 15x70 only £ 99.99

Visionary

FIRST VIEW3” starter telescope complete with fnderscope, table base and eyepieces.

£49.99

Clearview Binoculars: Four Square Chapel, Mapplewell. S75 6GG. Tel 01226 383736.

www.clearviewbinoculars.co.uk Callers very welcome, please check website for opening times.

Binocular Outlet. Check our website or visit us at our shows throughout the UK.

www.binocularoutlet.co.uk

The Far-Sighted binocular company is a group of independent specialist optical goods suppliers. For more information please visit www.far-sighted.co.uk.

Offers are subject to availability and at participating outlets only. Prices and specifcations are subject to change without notice.

LOW PRICES we’ll match any genuine web price!

Visionary Classic 10x50Good value and excellent value for money.

Kepler GL 10x50A strong and sturdy binocular - excellent value for money and a

great tool for viewing the night sky at a great price.

£29.99

£34.99

Visionary HDVery high quality optics at a great price. Traditional styled binoculars featuring BAK4 prisms, fully coated lenses, Long eye relief, rubber armour body.

HD 8x42 ......£69.99HD 8x56 ......£99.99HD 7x50 ......£79.99HD 10x50 ....£79.99

HUGE RANGE of eyepieces and accessories

102 EDtelescope outftwith 2” SWA eyepice,

2” 90M and 8.5x50 illuminated fnder

£799.00

Eyepieces & AccessoriesEYEPIECES/ACCESSORIES

Plossl 5mm (1.25”) ................................................................. £14.99 Plossl 10mm (1.25”) .............................................................. £14.99 Plossl 15mm (1.25”) .............................................................. £14.99 Plossl 20mm (1.25”) .............................................................. £14.99 Plossl 25mm (1.25”) .............................................................. £17.99 Plossl 30mm (1.25”) .............................................................. £17.99 Plossl 40mm (1.25”) ............................................................. £19.99 Super Wide angle 10mm (1.25”) ....................................... £39.99 Super Wide angle 20mm (1.25”) ....................................... £44.99 FF 8mm (1.25”) ....................................................................... £49.99 FF 12mm (1.25”) .................................................................... £49.99 FF 19mm (1.25”) .................................................................... £49.99 FF 27mm (1.25”) .................................................................... £49.99 SWA 26mm (2”) ..................................................................... £79.99 SWA 32mm (2”) ..................................................................... £79.99 SWA 38mm (2”) ..................................................................... £79.99 SWA82 8.8mm (1.25”) ...................................................... £129.99 SWA82 14mm (1.25”) ....................................................... £149.99 SWA82 24mm (2”) ............................................................. £199.99

HD 12x60 ....£89.99HD 15x70 ....£99.99HD 20x80 .£149.99HD 20x80T .£249.99

Olivon QB 10x50Excellent quality traditional styled binoculars. Rubber armoured, water resistant and BAK 4 optics.

Ostara Elinor 10x50BAK 4 prisms, Fully multi coated , waterproof and nitrogen flled.

£84.99

£179.99

Ostara Prophecy 10x50The ultimate in high quality viewing. Highest quality, full multicoated optics, prism and phase coatings for superb brightness, clarity and contrast. Waterproof and nitrogenflled, Fully checked and tested in the UK.

£299.99

Stockists of

Visionary Saxon

Visionary HD 15x70 only £ 99.99

Visionary

FIRST VIEW3” starter telescope complete with fnderscope, table base and eyepieces.

£49.99

Clearview Binoculars: Four Square Chapel, Mapplewell. S75 6GG. Tel 01226 383736.

www.clearviewbinoculars.co.uk Callers very welcome, please check website for opening times.

Binocular Outlet. Check our website or visit us at our shows throughout the UK.

www.binocularoutlet.co.uk

The Far-Sighted binocular company is a group of independent specialist optical goods suppliers. For more information please visit www.far-sighted.co.uk.

Offers are subject to availability and at participating outlets only. Prices and specifcations are subject to change without notice.

skills APRIL 95


Our resident equipment specialist cures your optical ailments and technical maladies

ma

ksu

tov

ca

sseg

ra

in il

lust

ra

tio

n b

y pa

ul

wo

ott

on

, pa

ul

wh

itfi

eld

Email your queries to [email protected]

Maksutov-Cassegrain telescopes are

designed to give a long focal length

within a short optical tube by using a

folded light path. The design requires

a meniscus correcting lens at the front

of the instrument. These can be quite

thick and heavy, so tend to limit the

maximum aperture size of amateur

instruments to less than 8 inches.

Typical focal ratios are in the region

of f/12 to f/15, so a typical 5-inch

telescope would have a focal length

of around 1,500mm, while an

8-inch version would have a focal

length around 2,700mm. Focal

lengths of this size give quite high

magnifcation with a given eyepiece

making Maksutov-Cassegrains

most suitable for Solar System

observing. However, they can also

Which eyepieces are suitable for Maksutov-Cassegrains and how can I ensure the widest feld of view? DaviD Frampton

be used to observe globular clusters

and many galaxies but the high

magnifcation Maksutov-Cassegrains

are capable of can result in quite a

narrow feld of view.

Some of the latest Maksutov-

Cassegrain telescopes can physically

take wide-feld 2-inch eyepieces. But

it’s worth bearing in mind that if the

telescope’s rear aperture is narrower

than the eyepiece’s feld stop, you

may not achieve a fully illuminated

feld of view.

Ideal eyepieces would be either the

1.25-inch 24mm Tele Vue Panoptic

or the Baader Hyperion 24mm, both

of which have a 68° apparent feld of

view. The use of a focal reducer with

this design is not recommended.

Will the Orion Mini-Guider be enough to guide my Celestron VX8 or do I need something bigger? Keith moore

Finder-guiders like the Orion

Mini-Guider, Altair Astro 60mm

Miniguider or Altair Astro

Finderscope (pictured right)

that have been modifed

with special adaptor rings

are becoming very popular

for autoguiding mounts

when imaging deep-sky objects.

Their lightness and compact

dimensions, combined with close coupling

to the imaging telescope, which reduces the risk of

fexure, makes them a compelling purchase. The

wide feld of view afforded by these diminutive

guide telescopes also makes the task of locating

suitable guide stars easy.

With the sub-pixel guiding accuracy provided

by modern autoguiding software, even the short

focal lengths of these mini-guiders can be used

to guide imaging telescopes with focal lengths

of over 1,200mm.

The Celestron VX8 is available as either an 8-inch

Newtonian Refector with a focal length of

1,000mm or an 8-inch Schmidt-Cassegrain with a

focal length of 2,032mm. These mini-guiders would

be suitable for the Newtonian but for the Schmidt-

Cassegrain, an 80mm refractor or off-axis guider

would be required for guiding.

Steve richards is a keen astro imager and an astronomy equipment expert

SKILLS

With Steve Richards

ScopedOctOr

Þ Maksutov-Cassegrains fold the light path to increase the scope’s focal length

StEVE’S TOP TIPWhat’s the best way to store my telescope for

long periods of time?

careful long-term storage of a telescope is

important to ensure that it remains in good

condition and ready for use. dust and moisture

are the greatest concerns, so you should choose

somewhere that is dry, well-ventilated but not

too warm and then take precautions to keep

dust at bay. ensure that the focuser tube is fully

retracted and ftted with a dust cap and that

the front of the telescope is also ftted with a

dust cap. if you don’t have the original cap,

a shower hat can often be used instead.

Primary mirrorStarlight

Starlight

Meniscus lens

Coated spot

Eyepiece

skills APRIL 95


Our resident equipment specialist cures your optical ailments and technical maladies

ma

ksu

tov

ca

sseg

ra

in il

lust

ra

tio

n b

y pa

ul

wo

ott

on

, pa

ul

wh

itfi

eld

Email your queries to [email protected]

Maksutov-Cassegrain telescopes are

designed to give a long focal length

within a short optical tube by using a

folded light path. The design requires

a meniscus correcting lens at the front

of the instrument. These can be quite

thick and heavy, so tend to limit the

maximum aperture size of amateur

instruments to less than 8 inches.

Typical focal ratios are in the region

of f/12 to f/15, so a typical 5-inch

telescope would have a focal length

of around 1,500mm, while an

8-inch version would have a focal

length around 2,700mm. Focal

lengths of this size give quite high

magnifcation with a given eyepiece

making Maksutov-Cassegrains

most suitable for Solar System

observing. However, they can also

Which eyepieces are suitable for Maksutov-Cassegrains and how can I ensure the widest feld of view? DaviD Frampton

be used to observe globular clusters

and many galaxies but the high

magnifcation Maksutov-Cassegrains

are capable of can result in quite a

narrow feld of view.

Some of the latest Maksutov-

Cassegrain telescopes can physically

take wide-feld 2-inch eyepieces. But

it’s worth bearing in mind that if the

telescope’s rear aperture is narrower

than the eyepiece’s feld stop, you

may not achieve a fully illuminated

feld of view.

Ideal eyepieces would be either the

1.25-inch 24mm Tele Vue Panoptic

or the Baader Hyperion 24mm, both

of which have a 68° apparent feld of

view. The use of a focal reducer with

this design is not recommended.

Will the Orion Mini-Guider be enough to guide my Celestron VX8 or do I need something bigger? Keith moore

Finder-guiders like the Orion

Mini-Guider, Altair Astro 60mm

Miniguider or Altair Astro

Finderscope (pictured right)

that have been modifed

with special adaptor rings

are becoming very popular

for autoguiding mounts

when imaging deep-sky objects.

Their lightness and compact

dimensions, combined with close coupling

to the imaging telescope, which reduces the risk of

fexure, makes them a compelling purchase. The

wide feld of view afforded by these diminutive

guide telescopes also makes the task of locating

suitable guide stars easy.

With the sub-pixel guiding accuracy provided

by modern autoguiding software, even the short

focal lengths of these mini-guiders can be used

to guide imaging telescopes with focal lengths

of over 1,200mm.

The Celestron VX8 is available as either an 8-inch

Newtonian Refector with a focal length of

1,000mm or an 8-inch Schmidt-Cassegrain with a

focal length of 2,032mm. These mini-guiders would

be suitable for the Newtonian but for the Schmidt-

Cassegrain, an 80mm refractor or off-axis guider

would be required for guiding.

Steve richards is a keen astro imager and an astronomy equipment expert

SKILLS

With Steve Richards

ScopedOctOr

Þ Maksutov-Cassegrains fold the light path to increase the scope’s focal length

StEVE’S TOP TIPWhat’s the best way to store my telescope for

long periods of time?

careful long-term storage of a telescope is

important to ensure that it remains in good

condition and ready for use. dust and moisture

are the greatest concerns, so you should choose

somewhere that is dry, well-ventilated but not

too warm and then take precautions to keep

dust at bay. ensure that the focuser tube is fully

retracted and ftted with a dust cap and that

the front of the telescope is also ftted with a

dust cap. if you don’t have the original cap,

a shower hat can often be used instead.

Primary mirrorStarlight

Starlight

Meniscus lens

Coated spot

Eyepiece

High ReflectivityCoating

www.orionoptics.co.uk

Increase the efficiency of yourreflector by up to 25%

tech enquiries: [email protected]

Telephone 01782 614200

Our HI-LUX coating can be applied to almost anyreflector, in virtually any condition or no matter howold. Improves the reflective efficiency of your mirrors.

Find out more onour website: Optics >Mirror Recoatingor call / email

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Contact Mike Alexander: Craiglemine Cottage, Glasserton,

Dumfries & Galloway DG8 8NE • 01988 500594

[email protected] • www.gallowayastro.com

We provide all you need with:

• Telescopes up to 400mm aperture

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• B&B accommodation and evening meals

• Skywatcher and Celestron Telescope Dealer

near the UK’s 1st Dark sky Park If you are inspired to learn more about the night sky, book your stay for a

great experience under the UK’s darkest skies. Now in business for 10 years.

High quality spectroscopic gratings designed specifcally for ease of use

with webcams, video and CCD imagers.

These simple devices make a perfect introduction to the fascinating world

of spectroscopy, revealing the hidden information contained in the light from

stars and other objects.

add a new dimension to your imaging

With thestar analyser

Used like standard 1.25” flters

Choice of 2 models, starting from

£95.30

See our website for more information

www.patonhawksley.co.uk

NortherN optics A s t r o A c c e s s o r i e s i n L i n c o l n s h i r e

Visit us (Weekends)

Waters Edge Visitors Centre Maltkiln Road, Barton Upon Humber

North Lincolnshire DN18 5JR

07779 122 121 (Weekends)

01724 782022 (Mon-Fri)

Open 10.00am-3.30pm (Sat & Sun)

www.northernoptics.co.uk

25

yE

AR

S

e x p e r i e n c e

Stockist ofEyepieces, flters, barlows,

camera adapters, binoculars

and much more

check

website

for latest

ofers

High ReflectivityCoating

www.orionoptics.co.uk

Increase the efficiency of yourreflector by up to 25%

tech enquiries: [email protected]

Telephone 01782 614200

Our HI-LUX coating can be applied to almost anyreflector, in virtually any condition or no matter howold. Improves the reflective efficiency of your mirrors.

Find out more onour website: Optics >Mirror Recoatingor call / email

Galloway astronomy Centre

Prices from £26 pppn

Contact Mike Alexander: Craiglemine Cottage, Glasserton,

Dumfries & Galloway DG8 8NE • 01988 500594

[email protected] • www.gallowayastro.com

We provide all you need with:

• Telescopes up to 400mm aperture

• Free help and guidance

• Beginner Astronomy Courses

• B&B accommodation and evening meals

• Skywatcher and Celestron Telescope Dealer

near the UK’s 1st Dark sky Park If you are inspired to learn more about the night sky, book your stay for a

great experience under the UK’s darkest skies. Now in business for 10 years.

High quality spectroscopic gratings designed specifcally for ease of use

with webcams, video and CCD imagers.

These simple devices make a perfect introduction to the fascinating world

of spectroscopy, revealing the hidden information contained in the light from

stars and other objects.

add a new dimension to your imaging

With thestar analyser

Used like standard 1.25” flters

Choice of 2 models, starting from

£95.30

See our website for more information

www.patonhawksley.co.uk

NortherN optics A s t r o A c c e s s o r i e s i n L i n c o l n s h i r e

Visit us (Weekends)

Waters Edge Visitors Centre Maltkiln Road, Barton Upon Humber

North Lincolnshire DN18 5JR

07779 122 121 (Weekends)

01724 782022 (Mon-Fri)

Open 10.00am-3.30pm (Sat & Sun)

www.northernoptics.co.uk

25

yE

AR

S

e x p e r i e n c e

Stockist ofEyepieces, flters, barlows,

camera adapters, binoculars

and much more

check

website

for latest

ofers

HOW WE RATE

Each category is given a mark out of fve stars according to how well it performs. The ratings are:

★★★★★ Outstanding ★★★★★ Very good ★★★★★ Good★★★★★ Average ★★★★★ Poor/Avoid

REVIEWS APRIL 97


Bringing you the best in equipment and accessories each month, as reviewed by our team of astro experts

Find out how the huge Meade

LX600 improves on its forebears

98

Reviews

This month’s reviews

First light

98Meade LX600-ACF

12-inch Schmidt-Cassegrain

102William Optics

GTF 102 fve-element astrograph

Books

110We rate

four of the latest astronomy titles

Gear

112 Including this

Baader Classic Q-Eyepiece Set

106QSI 683 WSG-8

CCD camera with in-built flter wheel

SEE INTERACTIVE 360° MODELS OF ALL OUR FIRST LIGHT REVIEWS AT WWW.SKYATNIGHTMAGAZINE.COM

Tried & tested

WW

W.T

hES

ECrE

TSTu

DIO

.nET

X 4

Find out more about how we review equipment at: www.skyatnightmagazine.com/scoring-categories

HOW WE RATE

Each category is given a mark out of fve stars according to how well it performs. The ratings are:

★★★★★ Outstanding ★★★★★ Very good ★★★★★ Good★★★★★ Average ★★★★★ Poor/Avoid

REVIEWS APRIL 97


Bringing you the best in equipment and accessories each month, as reviewed by our team of astro experts

Find out how the huge Meade

LX600 improves on its forebears

98

Reviews

This month’s reviews

First light

98Meade LX600-ACF

12-inch Schmidt-Cassegrain

102William Optics

GTF 102 fve-element astrograph

Books

110We rate

four of the latest astronomy titles

Gear

112 Including this

Baader Classic Q-Eyepiece Set

106QSI 683 WSG-8

CCD camera with in-built flter wheel

SEE INTERACTIVE 360° MODELS OF ALL OUR FIRST LIGHT REVIEWS AT WWW.SKYATNIGHTMAGAZINE.COM

Tried & tested

WW

W.T

hES

ECrE

TSTu

DIO

.nET

X 4

Find out more about how we review equipment at: www.skyatnightmagazine.com/scoring-categories

98

first light

• Price £5,760 with X-Wedge, £5,280 without

• Aperture 305mm (12 inches)

• Focal length 2,438mm (f/8)

• Focuser Internal dual speed 7:1 Crayford-style

• Mount Giant Field tripod

• Controller Autostar II

• Additional features GPS, True Level and North sensors, time chip, planetarium software

• Weight Telescope tube 16.3kg, drive base with fork arms 22.7kg, tripod 22.7kg

• Supplier Telescope House

• www.telescopehouse.com

• Tel 01342 837610

ViTAl STATS The Meade LX600 is, in the

manufacturer’s words, a giant

leap forward in telescope

design, creating a portable,

highly transportable and easy to set up

platform for observation and

astrophotography. We put that to the test

in this review of the 12-inch variant.

In this style of telescope, the tube is

incorporated within a heavy-duty fork

mounting assembly. A Go-To computer is ftted

in the base of the mount. Lifting this arrangement

onto a tripod or equatorial wedge is not for the

fainthearted, although the design of the LX600

does include a means to split the fork arms, so

reducing the component lifting weight.

There are two arm stubs fxed to the optical

tube – these connect to the main forks via two

bolted plates. A locating pin is provided for each

plate. One arm stub can’t be locked and swings

freely, making locating it that bit harder to ft.

Once in place we found it fddly and time-

consuming to ft all eight of the locking hex bolts

and washers in place, and far too easy to drop

them. In the dark this was frustrating.

ww

w.t

hes

ecre

tstu

dio

.net

x 3

words: pete lawrence

stellar starlock

The most innovative aspect of the LX600 system is StarLock. This comprises a wide-feld, 14.7º by 11.8º camera for general pointing and a 3-inch f/5 telescope, giving a 57.2 arcminute by 45.8 arcminute autoguiding setup. The StarLock assembly unobtrusively locks onto the main telescope tube and is connected to the main computer via a supplied cable.

Upon activating the Go-To, the wide-feld camera automatically locates a nearby bright star, which is initially centred. The scope then slews to the selected object, at which point the autoguider locks on. The whole process takes a bit longer than a direct Go-To, but the accuracy is better as a result. StarLock is described as producing arcsecond guiding accuracy, although conditions and set-up precision may affect this.

The system’s activity is indicated by a rather comforting red LED. Once we’d balanced the optical tube and set the guide rate, the system did the rest. Thanks to StarLock, the LX600 range offers large aperture telescopes with camera-enhanced Go-To capability and autoguiding for long-exposure astrophotography. That’s a pretty exciting prospect.

A bridge connection, via a pair of

nine-pin D-plug leads, is required to

allow the Go-To computer at the base

of the forks to communicate with the

declination drives across the fork

breaks. Another eight fddly thumb

screws need to be tightened to ensure

a good connection.

Our test setup included a sturdy

feld tripod, which is included, and an

optional Meade X-Wedge. This is a satisfyingly solid,

angled platform used to convert the LX600’s altaz fork

mount to equatorial mode for long-exposure imaging.

High-precision pointingThe LX600 includes a new feature known as

StarLock, which enables high-precision pointing

accuracy and autoguiding functionality. For

StarLock to work correctly, the telescope tube must

be well balanced. Rail-mounted counterweights

are provided to achieve this, but they require a

hex key to adjust their position – thumb screws

would have been better. We also found that we

had to adjust our guide rate to fairly low to stop

the StarLock from overcompensating. >

smart upgrades and refnements characterise this huge telescope

Schmidt-CassegrainSky SAyS…

The Meade LX600 is a formidable imaging platform despite its fddly set-up process

Meade LX600-ACF 12-inch

see an interactive 360° model of this scope at www.skyatnightmagazine.com/meadelx600

98

first light

• Price £5,760 with X-Wedge, £5,280 without


• Focal length 2,438mm (f/8)

• Focuser Internal dual speed 7:1 Crayford-style

• Mount Giant Field tripod

• Controller Autostar II

• Additional features GPS, True Level and North sensors, time chip, planetarium software

• Weight Telescope tube 16.3kg, drive base with fork arms 22.7kg, tripod 22.7kg

• Supplier Telescope House

• www.telescopehouse.com

• Tel 01342 837610

ViTAl STATS The Meade LX600 is, in the

manufacturer’s words, a giant

leap forward in telescope

design, creating a portable,

highly transportable and easy to set up

platform for observation and

astrophotography. We put that to the test

in this review of the 12-inch variant.

In this style of telescope, the tube is

incorporated within a heavy-duty fork

mounting assembly. A Go-To computer is ftted

in the base of the mount. Lifting this arrangement

onto a tripod or equatorial wedge is not for the

fainthearted, although the design of the LX600

does include a means to split the fork arms, so

reducing the component lifting weight.

There are two arm stubs fxed to the optical

tube – these connect to the main forks via two

bolted plates. A locating pin is provided for each

plate. One arm stub can’t be locked and swings

freely, making locating it that bit harder to ft.

Once in place we found it fddly and time-

consuming to ft all eight of the locking hex bolts

and washers in place, and far too easy to drop

them. In the dark this was frustrating.

ww

w.t

hes

ecre

tstu

dio

.net

x 3

words: pete lawrence

stellar starlock

The most innovative aspect of the LX600 system is StarLock. This comprises a wide-feld, 14.7º by 11.8º camera for general pointing and a 3-inch f/5 telescope, giving a 57.2 arcminute by 45.8 arcminute autoguiding setup. The StarLock assembly unobtrusively locks onto the main telescope tube and is connected to the main computer via a supplied cable.

Upon activating the Go-To, the wide-feld camera automatically locates a nearby bright star, which is initially centred. The scope then slews to the selected object, at which point the autoguider locks on. The whole process takes a bit longer than a direct Go-To, but the accuracy is better as a result. StarLock is described as producing arcsecond guiding accuracy, although conditions and set-up precision may affect this.

The system’s activity is indicated by a rather comforting red LED. Once we’d balanced the optical tube and set the guide rate, the system did the rest. Thanks to StarLock, the LX600 range offers large aperture telescopes with camera-enhanced Go-To capability and autoguiding for long-exposure astrophotography. That’s a pretty exciting prospect.

A bridge connection, via a pair of

nine-pin D-plug leads, is required to

allow the Go-To computer at the base

of the forks to communicate with the

declination drives across the fork

breaks. Another eight fddly thumb

screws need to be tightened to ensure

a good connection.

Our test setup included a sturdy

feld tripod, which is included, and an

optional Meade X-Wedge. This is a satisfyingly solid,

angled platform used to convert the LX600’s altaz fork

mount to equatorial mode for long-exposure imaging.

High-precision pointingThe LX600 includes a new feature known as

StarLock, which enables high-precision pointing

accuracy and autoguiding functionality. For

StarLock to work correctly, the telescope tube must

be well balanced. Rail-mounted counterweights

are provided to achieve this, but they require a

hex key to adjust their position – thumb screws

would have been better. We also found that we

had to adjust our guide rate to fairly low to stop

the StarLock from overcompensating. >

smart upgrades and refnements characterise this huge telescope

Schmidt-CassegrainSky SAyS…

The Meade LX600 is a formidable imaging platform despite its fddly set-up process

Meade LX600-ACF 12-inch

see an interactive 360° model of this scope at www.skyatnightmagazine.com/meadelx600


first light april 99

Zero-SHiFT FoCuSer

Meade has redesigned its old LX-range focuser to produce a new

mechanism that keeps the target frmly in view while focus is adjusted.

This overcomes a shortcoming of previous designs where the image could shift out of view as the focus

was adjusted. The new design offers coarse and fne (7:1) focus options.

X-Wedge

Meade’s newest equatorial wedge, this heavy-duty platform tilts the base of the LX600 forks so that the RA axis points at the north celestial pole. Fine adjustment is made through altitude and azimuth knobs.

AuToSTAr ii CoMpuTeriSed go-To

As with earlier models, the LX600 is equipped with the Meade Autostar II computerised controller. This system gives you telescope set-up and confguration options, as well as a database of 145,000 objects, which can be centred on at the touch of a few buttons.

SpLiT-Fork

deSign

Like the LX200 range before it, LX600 telescopes are heavy. Meade has engineered a clever way to separate the optical tube from the main forks, allowing the 12-inch LX600 to be just about assembled by one person. However, certain design aspects make the process of putting the scope back together a bit fddly.


first light april 99

Zero-SHiFT FoCuSer

Meade has redesigned its old LX-range focuser to produce a new

mechanism that keeps the target frmly in view while focus is adjusted.

This overcomes a shortcoming of previous designs where the image could shift out of view as the focus

was adjusted. The new design offers coarse and fne (7:1) focus options.

X-Wedge

Meade’s newest equatorial wedge, this heavy-duty platform tilts the base of the LX600 forks so that the RA axis points at the north celestial pole. Fine adjustment is made through altitude and azimuth knobs.

AuToSTAr ii CoMpuTeriSed go-To

As with earlier models, the LX600 is equipped with the Meade Autostar II computerised controller. This system gives you telescope set-up and confguration options, as well as a database of 145,000 objects, which can be centred on at the touch of a few buttons.

SpLiT-Fork

deSign

Like the LX200 range before it, LX600 telescopes are heavy. Meade has engineered a clever way to separate the optical tube from the main forks, allowing the 12-inch LX600 to be just about assembled by one person. However, certain design aspects make the process of putting the scope back together a bit fddly.

F/8 opTiCS

Another departure from earlier LX200 models is the use of f/8 rather than f/10 optics. This delivers a wider and brighter feld of view, allowing the scope to produce decent images of deep-sky objects as well as still keeping a good image scale for Solar System imaging and viewing.

Þ Our composite shot of M42 turned out beautifully

Þ Starlock-guided M82 plus the January 2014 supernova

ww

w.t

hesec

rets

tud

io.n

et,

pete

la

wren

ce x

2

100 first light april

first light

The Advanced Coma-Free (ACF) optics are a

delight to use. A view of the Orion Nebula gave lots

of beautiful detail in the swirling gas cloud, while

the tight trapezium star cluster took the guise of

diamonds scattered in ‘cotton wool’. Dark mottles

and edges of the nebula stood out superbly in the

high-contrast view and it was easy to get lost in the

sumptuous detail. Planetary imaging with the LX600

is really good, as StarLock helps to keep your target

centred in the feld of view. This would be a dream

system for taking planetary timelapse sequences.

A major criticism of previous LX models was the

image shift caused by the focuser. This has been fxed

for the LX600 – the focuser has been revamped

completely – and we didn’t experience any image shift

whatsoever. The focus knob is a little stiff though,

so for accurate high-magnifcation focusing we’d

recommend investing in an in-line electric focuser.

Further improvementsThe mount drives use large, 5.75-inch gears to help

maintain accuracy and provide smooth movements

without serious periodic error. Another great feature

of this setup is the way that it has been designed to

work from horizon-to-horizon without the need for

a meridian fip as the scope passes through the

north-south plane, something that some much more

expensive setups continue to experience.

Unlike previous LX folded-optic designs, the LX600

is f/8 rather than f/10. This gives a bigger, brighter

image and a wider natural feld of view. It also reduces

the tolerance required to maintain good pointing

accuracy for long exposures. If you’re a planetary or

lunar imager, the generous 2.4m focal length will still

offer good image scale without an optical amplifer.

The Meade LX600 is a formidable astro-imaging

platform despite its set-up process being awkward

and a little fddly. Counterweight thumb screws

instead of hex bolts and a better split-fork coupling

would really help the system achieve its goal as a

portable system. S


Verdict

Build And deSign ★★★★★

eASe OF uSe ★★★★★

FeATuReS ★★★★★

gO-TO/TRACking ACCuRACy ★★★★★

OPTiCS ★★★★★

OVeRAll ★★★★★

Sky SAyS… Now add these:

1. Meade zero image shift microfocuser

2. Explore Scientifc 3-inch 0.7x reducer-corrector

3. Revelation Quartz 2-inch dielectric diagonal

>

F/8 opTiCS

Another departure from earlier LX200 models is the use of f/8 rather than f/10 optics. This delivers a wider and brighter feld of view, allowing the scope to produce decent images of deep-sky objects as well as still keeping a good image scale for Solar System imaging and viewing.

Þ Our composite shot of M42 turned out beautifully

Þ Starlock-guided M82 plus the January 2014 supernova

ww

w.t

hesec

rets

tud

io.n

et,

pete

la

wren

ce x

2

100 first light april

first light

The Advanced Coma-Free (ACF) optics are a

delight to use. A view of the Orion Nebula gave lots

of beautiful detail in the swirling gas cloud, while

the tight trapezium star cluster took the guise of

diamonds scattered in ‘cotton wool’. Dark mottles

and edges of the nebula stood out superbly in the

high-contrast view and it was easy to get lost in the

sumptuous detail. Planetary imaging with the LX600

is really good, as StarLock helps to keep your target

centred in the feld of view. This would be a dream

system for taking planetary timelapse sequences.

A major criticism of previous LX models was the

image shift caused by the focuser. This has been fxed

for the LX600 – the focuser has been revamped

completely – and we didn’t experience any image shift

whatsoever. The focus knob is a little stiff though,

so for accurate high-magnifcation focusing we’d

recommend investing in an in-line electric focuser.

Further improvementsThe mount drives use large, 5.75-inch gears to help

maintain accuracy and provide smooth movements

without serious periodic error. Another great feature

of this setup is the way that it has been designed to

work from horizon-to-horizon without the need for

a meridian fip as the scope passes through the

north-south plane, something that some much more

expensive setups continue to experience.

Unlike previous LX folded-optic designs, the LX600

is f/8 rather than f/10. This gives a bigger, brighter

image and a wider natural feld of view. It also reduces

the tolerance required to maintain good pointing

accuracy for long exposures. If you’re a planetary or

lunar imager, the generous 2.4m focal length will still

offer good image scale without an optical amplifer.

The Meade LX600 is a formidable astro-imaging

platform despite its set-up process being awkward

and a little fddly. Counterweight thumb screws

instead of hex bolts and a better split-fork coupling

would really help the system achieve its goal as a

portable system. S


Verdict

Build And deSign ★★★★★

eASe OF uSe ★★★★★

FeATuReS ★★★★★

gO-TO/TRACking ACCuRACy ★★★★★

OPTiCS ★★★★★

OVeRAll ★★★★★


1. Meade zero image shift microfocuser

2. Explore Scientifc 3-inch 0.7x reducer-corrector

3. Revelation Quartz 2-inch dielectric diagonal

>

Solarscope manufacture complete h-alpha telescopes available in

unobstructed 50mm and 60mm apertures as well as a range of h-alpha

lter systems which can convert your existing astronomical telescope into a

high quality solar instrument. H-alpha lter systems are available in

unobstructed 50mm, 60mm, 70mm and 100mm aperture sizes.

The dedicated Solarview (SV) telescope range provides you with

everything you need to observe the Sun in h-alpha apart from a mount and

clear skies! These solar instruments are manufactured to the highest

quality and will give you views of our nearest star which will literally take

your breath away.

Observing the Sun through an h-alpha fi lter is an incredible experience…

The solar lter system (SF) range consists of a totally unobstructed front mounted etalon with a matching rear mounted blocking lter which ts

into your telescope’s eyepiece holder. A custom made adapter plate is used to securely mount the etalon over the front of your telescope. Using

laser industry techniques our lter systems are manufactured to the highest optical tolerances.

07624 435572 [email protected] www.solarscope.co.uk

Prestige hydrogen-alpha solar lters manufactured in the Isle of Man

For information on Solarscope fi lters Contact: Ken Huggett

Solarscope manufacture complete h-alpha telescopes available in

unobstructed 50mm and 60mm apertures as well as a range of h-alpha

lter systems which can convert your existing astronomical telescope into a

high quality solar instrument. H-alpha lter systems are available in

unobstructed 50mm, 60mm, 70mm and 100mm aperture sizes.

The dedicated Solarview (SV) telescope range provides you with

everything you need to observe the Sun in h-alpha apart from a mount and

clear skies! These solar instruments are manufactured to the highest

quality and will give you views of our nearest star which will literally take

your breath away.

Observing the Sun through an h-alpha fi lter is an incredible experience…

The solar lter system (SF) range consists of a totally unobstructed front mounted etalon with a matching rear mounted blocking lter which ts

into your telescope’s eyepiece holder. A custom made adapter plate is used to securely mount the etalon over the front of your telescope. Using

laser industry techniques our lter systems are manufactured to the highest optical tolerances.

07624 435572 [email protected] www.solarscope.co.uk

Prestige hydrogen-alpha solar lters manufactured in the Isle of Man

For information on Solarscope fi lters Contact: Ken Huggett

102


first light

• Price £1,669

• Optics FPL53 triplet with rear two-element feld fattener


• Focal length 703mm (f/6.9)

• Length 786mm with dew shield extended, 659mm with dew shield retracted

• Focuser 2.5-inch dual-speed 10:1 rack and pinion

• Extras Tube rings

• Weight 5kg excluding tube rings

• Supplier The Widescreen Centre

• www.widescreen-centre.co.uk

• Tel 020 7935 2580

ViTAL STATS

William Optics produces two versions

of its 4-inch apo refractor: one a

conventional triplet lens and the

other a fve-element astrograph – it’s

the latter we’re reviewing here. The word astrograph

indicates that the telescope is designed with

astrophotography in mind.

It arrived in a standard cardboard box, but on

opening that up we were greeted by a beautifully

made and sturdy case with ample padding to protect

the telescope in transit. The instrument itself is

strikingly attractive, fnished in an off-white

stippled-powder coat with three contrasting cerise

bands of anodised aluminium.

William Optics has recently changed from

using Crayford focusers to rack and pinion

alternatives, and the 2.5-inch unit supplied

with the review telescope worked smoothly

and fawlessly. With a maximum extension

of 80mm there is plenty of focus travel, but

not knowing exactly where the sensor would

be when we achieved focus we inserted a 50.8mm

extension tube in front of our camera and off-axis

guider. This turned out to be a pretty good guess

– we achieved crisp focus at an extension of just

18mm, which left plenty of the focus tube within

the focuser for stability.

The focuser easily handled the weight of our

imaging system using both the coarse and fne focus

knobs, and there was only the smallest amount of

all

ph

oto

s: w

ww

.th

esec

rets

tud

io.n

et

words: steve richards

quintet of quality

The GTF 102 astrograph has an unusual optical system, comprising fve elements arranged in two groups. The primary lens is an air-spaced triplet that uses FPL53 extra-low dispersion glass to bring all the colours of light to the same focus point. This is important to avoid chromatic aberration, which results in unwanted coloured halos around bright objects. The three lens elements are housed in a fully adjustable, CNC-machined lens cell.

The second group is made up of two lens elements (also made from extra-low dispersion glass), which are set inside the telescope tube. They act as a feld fattener to combat the feld curvature that is normally present in a refractor. Field curvature causes stars at the edges of the feld of view to appear elongated, which is a particular problem in deep-sky imaging.

All of the lens surfaces are fully multicoated to increase light transmission and reduce unwanted refections. Since the feld fattener is built in, there is no critical spacing issue when using a camera, so installing a flter wheel and an off-axis guider is straightforward.

image shift when we tightened up the locking bolt

once we had achieved focus.

The telescope produced a feld of view 1° and 54

arcminutes wide by 1° and 16 arcminutes deep with

our test camera, a one-shot-colour CCD with an

APS-C sensor. This area is just large enough to

capture the Rosette Nebula and some surrounding

stars. With a focal ratio of f/6.9, this telescope is

relatively slow compared to many astrographs,

but this does have some advantages – chromatic

aberration and feld curvature are slightly easier

to control with longer focal length lenses.

Shapely starsAs the CCD camera we used for this review had an

APS-C sensor, the star shapes in our images are a

good indicator for what to expect with a typical

DSLR camera, which has a very similarly sized

sensor. We were very pleasantly surprised by the

shape of the stars across the feld of view

and right into the corners. The

two-element internal feld

fattener was certainly

doing its job

An exciting imaging scope that performs just as well visually

fve-element astrographWilliam Optics GTF 102

>

see an interactive 360° model of this telescope at www.skyatnightmagazine.com/wogtf102

102


first light

• Price £1,669

• Optics FPL53 triplet with rear two-element feld fattener


• Focal length 703mm (f/6.9)

• Length 786mm with dew shield extended, 659mm with dew shield retracted

• Focuser 2.5-inch dual-speed 10:1 rack and pinion

• Extras Tube rings

• Weight 5kg excluding tube rings

• Supplier The Widescreen Centre

• www.widescreen-centre.co.uk

• Tel 020 7935 2580

ViTAL STATS

William Optics produces two versions

of its 4-inch apo refractor: one a

conventional triplet lens and the

other a fve-element astrograph – it’s

the latter we’re reviewing here. The word astrograph

indicates that the telescope is designed with

astrophotography in mind.

It arrived in a standard cardboard box, but on

opening that up we were greeted by a beautifully

made and sturdy case with ample padding to protect

the telescope in transit. The instrument itself is

strikingly attractive, fnished in an off-white

stippled-powder coat with three contrasting cerise

bands of anodised aluminium.

William Optics has recently changed from

using Crayford focusers to rack and pinion

alternatives, and the 2.5-inch unit supplied

with the review telescope worked smoothly

and fawlessly. With a maximum extension

of 80mm there is plenty of focus travel, but

not knowing exactly where the sensor would

be when we achieved focus we inserted a 50.8mm

extension tube in front of our camera and off-axis

guider. This turned out to be a pretty good guess

– we achieved crisp focus at an extension of just

18mm, which left plenty of the focus tube within

the focuser for stability.

The focuser easily handled the weight of our

imaging system using both the coarse and fne focus

knobs, and there was only the smallest amount of

all

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oto

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.th

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quintet of quality

The GTF 102 astrograph has an unusual optical system, comprising fve elements arranged in two groups. The primary lens is an air-spaced triplet that uses FPL53 extra-low dispersion glass to bring all the colours of light to the same focus point. This is important to avoid chromatic aberration, which results in unwanted coloured halos around bright objects. The three lens elements are housed in a fully adjustable, CNC-machined lens cell.

The second group is made up of two lens elements (also made from extra-low dispersion glass), which are set inside the telescope tube. They act as a feld fattener to combat the feld curvature that is normally present in a refractor. Field curvature causes stars at the edges of the feld of view to appear elongated, which is a particular problem in deep-sky imaging.

All of the lens surfaces are fully multicoated to increase light transmission and reduce unwanted refections. Since the feld fattener is built in, there is no critical spacing issue when using a camera, so installing a flter wheel and an off-axis guider is straightforward.

image shift when we tightened up the locking bolt

once we had achieved focus.

The telescope produced a feld of view 1° and 54

arcminutes wide by 1° and 16 arcminutes deep with

our test camera, a one-shot-colour CCD with an

APS-C sensor. This area is just large enough to

capture the Rosette Nebula and some surrounding

stars. With a focal ratio of f/6.9, this telescope is

relatively slow compared to many astrographs,

but this does have some advantages – chromatic

aberration and feld curvature are slightly easier

to control with longer focal length lenses.

Shapely starsAs the CCD camera we used for this review had an

APS-C sensor, the star shapes in our images are a

good indicator for what to expect with a typical

DSLR camera, which has a very similarly sized

sensor. We were very pleasantly surprised by the

shape of the stars across the feld of view

and right into the corners. The

two-element internal feld

fattener was certainly

doing its job

An exciting imaging scope that performs just as well visually

fve-element astrographWilliam Optics GTF 102

>

see an interactive 360° model of this telescope at www.skyatnightmagazine.com/wogtf102


first light APRIL 103

Sky SAyS…

All of the lens surfaces are fully multicoated to increase light transmission and reduce unwanted refections

Rack and PiniOn

FOcuSeR

The 2.5-inch rack and pinion focuser has anti-marring brass

compression rings, can be rotated through 360° and is very

smooth in operation, with minimal image shift when applying the

simple lock mechanism. The 10:1 two-speed mechanism handled

the weight of our imaging camera, off-axis guider and

guide camera with ease.

ReTRacTable deW Shield

The 127mm-long dew shield does an excellent job of defecting extraneous light and keeping the dew at bay. The front is capped with an aluminium dust cover that simply and safely slips on and off. A convenient thumbscrew locks the shield in its extended position.

Tube RinGS

The 105mm diameter, CNC-machined tube rings have a crisp, black crackle fnish. With a choice of mounting holes in both upper and lower mountings, they accommodate various types of dovetail bar and accessories. Nylon spacers on the locking bolts help to protect the clamp surfaces.

TeleScOPe Tube

The construction of the telescope tube, which is machined from aluminium, underpins the optical system’s stability – the whole telescope felt very solid indeed. Internally the tube is fnished in matt black and has three knife-edge baffes, which together help to reduce internal refections and increase the contrast of the view.


first light APRIL 103

Sky SAyS…

All of the lens surfaces are fully multicoated to increase light transmission and reduce unwanted refections

Rack and PiniOn

FOcuSeR

The 2.5-inch rack and pinion focuser has anti-marring brass

compression rings, can be rotated through 360° and is very

smooth in operation, with minimal image shift when applying the

simple lock mechanism. The 10:1 two-speed mechanism handled

the weight of our imaging camera, off-axis guider and

guide camera with ease.

ReTRacTable deW Shield

The 127mm-long dew shield does an excellent job of defecting extraneous light and keeping the dew at bay. The front is capped with an aluminium dust cover that simply and safely slips on and off. A convenient thumbscrew locks the shield in its extended position.

Tube RinGS

The 105mm diameter, CNC-machined tube rings have a crisp, black crackle fnish. With a choice of mounting holes in both upper and lower mountings, they accommodate various types of dovetail bar and accessories. Nylon spacers on the locking bolts help to protect the clamp surfaces.

TeleScOPe Tube

The construction of the telescope tube, which is machined from aluminium, underpins the optical system’s stability – the whole telescope felt very solid indeed. Internally the tube is fnished in matt black and has three knife-edge baffes, which together help to reduce internal refections and increase the contrast of the view.

ww

w.t

hesec

rets

tud

io.n

et,

ste

ve r

ich

ard

s

first light

Verdict

BuiLd And dESign ★★★★★

EASE OF uSE ★★★★★

FEATurES ★★★★★

imAging QuALiTy ★★★★★

OPTicS ★★★★★

OVErALL ★★★★★

and so too was the triplet lens, as chromatic

aberration was also well controlled. There was

some vignetting, which caused the edges of the

feld of view to be darker than the centre, but this

was easily corrected by calibrating the images

with suitable fat frames. One problem that can

occur with multi-element designs like this is

that of focus shift with temperature change.

However, we didn’t fnd it necessary to adjust

focus during our 4.5-hour imaging session

despite a thick frost forming on the inside of

our domed observatory.

Although the GTF 102 is designed as an

astrograph, we couldn’t resist using it for some

simple observing and we weren’t disappointed.

Using our own 2-inch dielectric diagonal and

eyepieces we enjoyed some glorious views of

Jupiter and the gibbous Moon.

The lack of false colour in our imaging tests was

corroborated through the eyepiece. Confrmed too

were excellent star shapes right out to the edge of

the feld of view. We couldn’t ignore the presence

of the Orion Nebula and the large swathe of

nebulosity observed through our 17mm eyepiece

was particularly memorable, as was the crisp,

sparkly view of the Pleiades star cluster.

We thoroughly enjoyed our experiences with the

GTF 102 and would recommend the telescope to

any astrophotographer searching for an imaging

instrument that removes the pain of achieving a fat

feld with stars pin sharp to the edge.


SOFT caSe

The GTF 102 is supplied with a high-quality soft padded case. It is very substantial and protects the telescope in transit very well indeed. With both carry handles and a shoulder strap, transporting the scope is easy.


1. William Optics 50mm guidescope with mounting bracket

2. Atik 383L+ CCD camera

3. Sky-Watcher AZ-EQ6 GT mount and tripod

>

104 first light APRIL

S

Þ Our image of the rosette nebula in monoceros exhibits clean star shapes right to the edges of the feld

ww

w.t

hesec

rets

tud

io.n

et,

ste

ve r

ich

ard

s

first light

Verdict

BuiLd And dESign ★★★★★

EASE OF uSE ★★★★★

FEATurES ★★★★★

imAging QuALiTy ★★★★★

OPTicS ★★★★★

OVErALL ★★★★★

and so too was the triplet lens, as chromatic

aberration was also well controlled. There was

some vignetting, which caused the edges of the

feld of view to be darker than the centre, but this

was easily corrected by calibrating the images

with suitable fat frames. One problem that can

occur with multi-element designs like this is

that of focus shift with temperature change.

However, we didn’t fnd it necessary to adjust

focus during our 4.5-hour imaging session

despite a thick frost forming on the inside of

our domed observatory.

Although the GTF 102 is designed as an

astrograph, we couldn’t resist using it for some

simple observing and we weren’t disappointed.

Using our own 2-inch dielectric diagonal and

eyepieces we enjoyed some glorious views of

Jupiter and the gibbous Moon.

The lack of false colour in our imaging tests was

corroborated through the eyepiece. Confrmed too

were excellent star shapes right out to the edge of

the feld of view. We couldn’t ignore the presence

of the Orion Nebula and the large swathe of

nebulosity observed through our 17mm eyepiece

was particularly memorable, as was the crisp,

sparkly view of the Pleiades star cluster.

We thoroughly enjoyed our experiences with the

GTF 102 and would recommend the telescope to

any astrophotographer searching for an imaging

instrument that removes the pain of achieving a fat

feld with stars pin sharp to the edge.


SOFT caSe

The GTF 102 is supplied with a high-quality soft padded case. It is very substantial and protects the telescope in transit very well indeed. With both carry handles and a shoulder strap, transporting the scope is easy.


1. William Optics 50mm guidescope with mounting bracket

2. Atik 383L+ CCD camera

3. Sky-Watcher AZ-EQ6 GT mount and tripod

>

104 first light APRIL

S

Þ Our image of the rosette nebula in monoceros exhibits clean star shapes right to the edges of the feld

f1telescopesQuality advice • excellent service • competitive prices

Celestron, Baader

Planetarium, meade,

skywatCher, Vixen, Coronado

and more…

Part exchange welcome.

we also buy and sell used telescopes and

provide service and repair facilities.

visit our shop at:

unit a3, st GeorGe’s Business Park,

Castle road, sittinGBourne, kent

me10 3tB. 01795 432702

check out our website:

www.f1telescopes.co.uk

the only astro sPeCialist in kent

A large range of telescopes and accessories from the world’s leading suppliers.

Tel: 01903 247317 • 16 Mulberry Lane, Goring-by-Sea, Worthing, West Sussex

www.sussex-astronomy-centre.co.uk

Free Parking

Friendly personal service for ALL your astronomy needs.

Beginners most welcome!

Sussex Astronomy Centre Meade Advanced Product Dealer

Celestron, Sky-Watcher, Meade main stockist for Sussex

Friendly Advice and After-Sales Service.

www.green-witch.com

Buy online with confdence or visit our well stocked showrooms.

Birstall, West YorksWF17 9ES

01924 477719

Gransden, Beds & CambsSG19 3PF

01767 677025

Astronomy

Roudham • NoRfolk NR16 2QN

01953 423111 / 07967 376336

specialists in the construction and installation

of rolling roof observatories and telescope

piers for the home astronomer.

Friendly and Reliable Service.

www.homeobservatoryuk.com

home obseRvatoRy uk

Any Size • Warm Rooms Wheelchair/Disabled Access • Electric Roof

Visit uS at

f1telescopesQuality advice • excellent service • competitive prices

Celestron, Baader

Planetarium, meade,

skywatCher, Vixen, Coronado

and more…

Part exchange welcome.

we also buy and sell used telescopes and

provide service and repair facilities.

visit our shop at:

unit a3, st GeorGe’s Business Park,

Castle road, sittinGBourne, kent

me10 3tB. 01795 432702

check out our website:

www.f1telescopes.co.uk

the only astro sPeCialist in kent

A large range of telescopes and accessories from the world’s leading suppliers.

Tel: 01903 247317 • 16 Mulberry Lane, Goring-by-Sea, Worthing, West Sussex

www.sussex-astronomy-centre.co.uk

Free Parking

Friendly personal service for ALL your astronomy needs.

Beginners most welcome!

Sussex Astronomy Centre Meade Advanced Product Dealer

Celestron, Sky-Watcher, Meade main stockist for Sussex

Friendly Advice and After-Sales Service.

www.green-witch.com

Buy online with confdence or visit our well stocked showrooms.

Birstall, West YorksWF17 9ES

01924 477719

Gransden, Beds & CambsSG19 3PF

01767 677025

Astronomy

Roudham • NoRfolk NR16 2QN

01953 423111 / 07967 376336

specialists in the construction and installation

of rolling roof observatories and telescope

piers for the home astronomer.

Friendly and Reliable Service.

www.homeobservatoryuk.com

home obseRvatoRy uk

Any Size • Warm Rooms Wheelchair/Disabled Access • Electric Roof

Visit uS at

Tried & tested

• Price £3,149

• Size 141x149x84mm

• Sensor Truesense Imaging KAF-8300

• Sensor size 17.96x13.52mm, 22.5mm diagonal

• Pixels 3326 x 2504

• Back focus 50.2mm

• Weight 1.66kg

• Extras Peli case, AC mains power supply, USB cable, ST4 cable, Allen keys, 2-inch nosepiece adaptor, CD

• Supplier Ian King Imaging

• www.iankingimaging.com

• Tel 01580 212356

ViTal STaTS

Astrophotography has rightly become

a very important and enjoyable aspect

of astronomy: it is only through

the capture of long-exposure images

that the true colourful beauty and detail of

deep-sky objects can be appreciated. Modern

DSLR cameras can capture this detail and much

of the colour of these objects, but dedicated

astronomical CCDs such as the QSI 683 WSG-8

can do it much better. This is because they have

built-in cooling to reduce thermal noise from the

sensor and are not hampered by infrared flters

designed for daytime use.

The QSI 683 WSG-8 CCD camera, frst released

in 2012, is designed to overcome several of the

issues that cause the most angst among astro

imagers. The inclusion of an integrated flter wheel

and an off-axis guider with enough space to use

with a standard coma corrector, feld fattener or

focal reducer is one of these good ideas.

The camera is supplied in a high-quality Peli

1400 case, giving the contents excellent protection.

Included in the case is an AC mains power supply,

USB cable, ST4 cable, a set of Allen keys, a 2-inch

nosepiece adaptor and a CD. Plug-ins for MaxIm DL,

CCDSoft and AstroArt are included on the CD,

CCD camera

ww

w.t

hes

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et

x 4

, ste

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2


106


along with an ASCOM driver and a full set

of well-written and comprehensive manuals.

Plug-ins for other image capture programs are

available for download from the QSI website

(www.QSimaging.com).

Quality manufacturingAt 1.66kg, the camera feels very substantially built

and closer inspection confrms the quality of the

manufacturing. Great attention to detail has been

expended on both the external case and the

internal components, and we couldn’t help but

be impressed with how it all ftted together. The

built-in flter wheel possesses eight slots, which we

populated with our own flters: luminance, red,

green, blue, hydrogen-alpha, oxygen III, sulphur II

and hydrogen-beta. Having such a variety of flters

available at one time makes for very fexible

imaging as it is easy to choose the right flter for

the celestial object at hand.

Deep-sky imaging requires long exposures, so

it is imperative to ensure that your mount tracks

very accurately if you want to avoid stars trails. The

‘G’ in WSG stands for guider – the camera has a

built-in off-axis guider installed in front of the flter

wheel. This very convenient arrangement ensures

QSI 683

Sky SayS…We imaged a range of objects and were very impressed with the sensitivity and lack of thermal noise

We review well-established equipment that’s stood the test of time

A built-in filter wheel and off-axis guider make for a neat package

owner’s observationsName Steve Richardslocation Nr Wiston, West SussexEquipment QSI 683 WSG-8Owner since June 2013

I bought the QSI 683 WSG-8 mono CCD camera specifcally for use on my dual imaging system. I use a mono CCD camera on one telescope and a one-shot colour CCD camera on a second telescope, which allows me to capture two sets of data simultaneously that I can combine later on. My original mono CCD camera had a much smaller sensor (8.98x6.71mm)

than my colour camera and this mismatch reduced the size of my fnished images too much. The larger sensor in the QSI 683 WSG-8 (17.96x13.52mm) allows me to capture much better matched images at a far higher resolution.

Even though the QSI 683 WSG-8’s KAF-8300 sensor was much larger, I was still able to use my existing set of 1.25-inch flters, which was a real advantage in terms of cost. Such was the quality of the data captured by the new camera that it wasn’t long before I started concentrating on using just this camera for most of my imaging.

WSG-8

>

see an interactive 360° model of this camera at www.skyatnightmagazine.com/qsi683

Tried & tested

• Price £3,149

• Size 141x149x84mm

• Sensor Truesense Imaging KAF-8300

• Sensor size 17.96x13.52mm, 22.5mm diagonal

• Pixels 3326 x 2504

• Back focus 50.2mm

• Weight 1.66kg

• Extras Peli case, AC mains power supply, USB cable, ST4 cable, Allen keys, 2-inch nosepiece adaptor, CD

• Supplier Ian King Imaging

• www.iankingimaging.com

• Tel 01580 212356

ViTal STaTS

Astrophotography has rightly become

a very important and enjoyable aspect

of astronomy: it is only through

the capture of long-exposure images

that the true colourful beauty and detail of

deep-sky objects can be appreciated. Modern

DSLR cameras can capture this detail and much

of the colour of these objects, but dedicated

astronomical CCDs such as the QSI 683 WSG-8

can do it much better. This is because they have

built-in cooling to reduce thermal noise from the

sensor and are not hampered by infrared flters

designed for daytime use.

The QSI 683 WSG-8 CCD camera, frst released

in 2012, is designed to overcome several of the

issues that cause the most angst among astro

imagers. The inclusion of an integrated flter wheel

and an off-axis guider with enough space to use

with a standard coma corrector, feld fattener or

focal reducer is one of these good ideas.

The camera is supplied in a high-quality Peli

1400 case, giving the contents excellent protection.

Included in the case is an AC mains power supply,

USB cable, ST4 cable, a set of Allen keys, a 2-inch

nosepiece adaptor and a CD. Plug-ins for MaxIm DL,

CCDSoft and AstroArt are included on the CD,

CCD camera

ww

w.t

hes

ecrets

tud

io.n

et

x 4

, ste

ve

ric

ha

rd

s x

2


106


along with an ASCOM driver and a full set

of well-written and comprehensive manuals.

Plug-ins for other image capture programs are

available for download from the QSI website

(www.QSimaging.com).

Quality manufacturingAt 1.66kg, the camera feels very substantially built

and closer inspection confrms the quality of the

manufacturing. Great attention to detail has been

expended on both the external case and the

internal components, and we couldn’t help but

be impressed with how it all ftted together. The

built-in flter wheel possesses eight slots, which we

populated with our own flters: luminance, red,

green, blue, hydrogen-alpha, oxygen III, sulphur II

and hydrogen-beta. Having such a variety of flters

available at one time makes for very fexible

imaging as it is easy to choose the right flter for

the celestial object at hand.

Deep-sky imaging requires long exposures, so

it is imperative to ensure that your mount tracks

very accurately if you want to avoid stars trails. The

‘G’ in WSG stands for guider – the camera has a

built-in off-axis guider installed in front of the flter

wheel. This very convenient arrangement ensures

QSI 683

Sky SayS…We imaged a range of objects and were very impressed with the sensitivity and lack of thermal noise

We review well-established equipment that’s stood the test of time

A built-in filter wheel and off-axis guider make for a neat package

owner’s observationsName Steve Richardslocation Nr Wiston, West SussexEquipment QSI 683 WSG-8Owner since June 2013

I bought the QSI 683 WSG-8 mono CCD camera specifcally for use on my dual imaging system. I use a mono CCD camera on one telescope and a one-shot colour CCD camera on a second telescope, which allows me to capture two sets of data simultaneously that I can combine later on. My original mono CCD camera had a much smaller sensor (8.98x6.71mm)

than my colour camera and this mismatch reduced the size of my fnished images too much. The larger sensor in the QSI 683 WSG-8 (17.96x13.52mm) allows me to capture much better matched images at a far higher resolution.

Even though the QSI 683 WSG-8’s KAF-8300 sensor was much larger, I was still able to use my existing set of 1.25-inch flters, which was a real advantage in terms of cost. Such was the quality of the data captured by the new camera that it wasn’t long before I started concentrating on using just this camera for most of my imaging.

WSG-8

>

see an interactive 360° model of this camera at www.skyatnightmagazine.com/qsi683


tried & tested april 107

KAF-8300 SenSor

The KAF-8300 sensor conveniently bridges the gap between the typically affordable but

smaller Sony sensors and their larger and much more expensive APS C or large format counterparts. With 8.3 megapixels across its

surface and generous size (5.4μm) pixels, you can capture wide high-resolution images

without sacrifcing sensitivity.

TWo-STAGe PelTIer CoolInG

The camera uses a two-stage Peltier thermoelectric cooling system with two internal fans and set point cooling to reduce image noise caused by heat from the sensor during long exposures. This system is capable of cooling the sensor down to 45°C below the ambient temperature.

BuIlT-In oFF-AxIS GuIDer

An autoguiding system is vital for accurate tracking during long-exposure imaging; the most accurate way to do this is with an off-axis guider and guide camera. The QSI 683 WSG-8 has a neatly installed off-axis guider in front of the flter wheel, ensuring that only unfltered light reaches the guide camera.

SmAll DePTh

Although the camera incorporates both a flter wheel and an off-axis guider, its total depth from the front mounting plate to the sensor is only 50.2mm. This means that a simple 6mm T-extension tube will make the camera compatible with the industry standard sensor to focal reducer-feld fattener distance of 56mm.


tried & tested april 107

KAF-8300 SenSor

The KAF-8300 sensor conveniently bridges the gap between the typically affordable but

smaller Sony sensors and their larger and much more expensive APS C or large format counterparts. With 8.3 megapixels across its

surface and generous size (5.4μm) pixels, you can capture wide high-resolution images

without sacrifcing sensitivity.

TWo-STAGe PelTIer CoolInG

The camera uses a two-stage Peltier thermoelectric cooling system with two internal fans and set point cooling to reduce image noise caused by heat from the sensor during long exposures. This system is capable of cooling the sensor down to 45°C below the ambient temperature.

BuIlT-In oFF-AxIS GuIDer

An autoguiding system is vital for accurate tracking during long-exposure imaging; the most accurate way to do this is with an off-axis guider and guide camera. The QSI 683 WSG-8 has a neatly installed off-axis guider in front of the flter wheel, ensuring that only unfltered light reaches the guide camera.

SmAll DePTh

Although the camera incorporates both a flter wheel and an off-axis guider, its total depth from the front mounting plate to the sensor is only 50.2mm. This means that a simple 6mm T-extension tube will make the camera compatible with the industry standard sensor to focal reducer-feld fattener distance of 56mm.

that the use of flters

has no effect on the light

falling on the guide

camera, thus ensuring

the greatest chance of

fnding a suitable guide

star even with very short

exposures. An off-axis

guider uses a small

pick-off prism, placed

just outside the cone

of light falling on the

imaging sensor, to

divert light from a

test star to the guide camera for analysis of

unwanted movement and subsequent mount

correction under software control. This provides

a very accurate method of autoguiding.

The short turret on top of the camera’s casing

is machined with a male C-thread, making it

compatible with various guide cameras. Adjustment

of the guide camera’s focus was very simply

carried out by slackening a single grub screw

using one of the supplied Allen keys and rotating

the focus ring around its thread.

The KAF-8300 sensor is a ‘full frame’ chip,

which means that unlike many sensors used

in astronomical CCD cameras it requires a

mechanical shutter, and the one used in the

QSI 683 WSG-8 operates quietly and smoothly.

We imaged a range of objects with the camera and

were very impressed with its sensitivity and lack

of thermal noise during exposures of up to

20 minutes. We would thoroughly recommend

the QSI 683 WSG-8 to intermediate or advanced

astrophotographers looking to upgrade to an

all-in-one mono camera, flter wheel and

off-axis guider imaging solution.

stev

e r

ich

ard

s x

3

108 tried & tested april

Tried & tested

BuIlT-In FIlTer Wheel

Despite the camera’s relatively large sensor, it only requires 1.25-inch flters. Up to eight of these can be installed in the built-in flter wheel at a time. Because the flter wheel is integrated into the camera, only one power cable and one USB cable are required, which cuts down on the usual tangle of wires.

S


Verdict

Build aNd dESigN ★★★★★

CONNECTiViTy ★★★★★

EaSE Of uSE ★★★★★

fEaTurES ★★★★★

imagiNg QualiTy ★★★★★

OVErall ★★★★★

Sky SayS… Now add these:

1. Starlight Xpress Lodestar autoguider

2. QSI EOS lens adaptor

3. QSI C mount lens adaptor

Our composite shot of NgC 6888, comprised of

seven 600-second frames: fve in Ha and two in Oiii

The Cygnus loop in Ha; the large flter wheel makes it easy to pick the right wavelength for the job

>

that the use of flters

has no effect on the light

falling on the guide

camera, thus ensuring

the greatest chance of

fnding a suitable guide

star even with very short

exposures. An off-axis

guider uses a small

pick-off prism, placed

just outside the cone

of light falling on the

imaging sensor, to

divert light from a

test star to the guide camera for analysis of

unwanted movement and subsequent mount

correction under software control. This provides

a very accurate method of autoguiding.

The short turret on top of the camera’s casing

is machined with a male C-thread, making it

compatible with various guide cameras. Adjustment

of the guide camera’s focus was very simply

carried out by slackening a single grub screw

using one of the supplied Allen keys and rotating

the focus ring around its thread.

The KAF-8300 sensor is a ‘full frame’ chip,

which means that unlike many sensors used

in astronomical CCD cameras it requires a

mechanical shutter, and the one used in the

QSI 683 WSG-8 operates quietly and smoothly.

We imaged a range of objects with the camera and

were very impressed with its sensitivity and lack

of thermal noise during exposures of up to

20 minutes. We would thoroughly recommend

the QSI 683 WSG-8 to intermediate or advanced

astrophotographers looking to upgrade to an

all-in-one mono camera, flter wheel and

off-axis guider imaging solution.

stev

e r

ich

ard

s x

3

108 tried & tested april

Tried & tested

BuIlT-In FIlTer Wheel

Despite the camera’s relatively large sensor, it only requires 1.25-inch flters. Up to eight of these can be installed in the built-in flter wheel at a time. Because the flter wheel is integrated into the camera, only one power cable and one USB cable are required, which cuts down on the usual tangle of wires.

S


Verdict

Build aNd dESigN ★★★★★

CONNECTiViTy ★★★★★

EaSE Of uSE ★★★★★

fEaTurES ★★★★★

imagiNg QualiTy ★★★★★

OVErall ★★★★★

Sky SayS… Now add these:

1. Starlight Xpress Lodestar autoguider

2. QSI EOS lens adaptor

3. QSI C mount lens adaptor

Our composite shot of NgC 6888, comprised of

seven 600-second frames: fve in Ha and two in Oiii

The Cygnus loop in Ha; the large flter wheel makes it easy to pick the right wavelength for the job

>

110


BooksRATINGS

★★★★★ Outstanding ★★★★★ Good ★★★★★ Average★★★★★ Poor★★★★★ Avoid

Two minuTes

wiTh DaviD

walTham

What inspired you to write the book?Ten years ago it occurred

to me that the simple question ‘Is Earth an unusual planet?’ brought my passions of astronomy and geology together. We can’t understand Earth properly without answering this question and we can’t do that without looking at how our world fts into the wider Universe.

Do you think life has evolved elsewhere?Defnitely. The basic idea behind Lucky Planet is that the Universe is so large that even very odd places like Earth are inevitable. I think Earth is so rare that we’re unlikely to ever fnd another world with a biosphere as complex as ours; the fip side of this argument is that there are probably many such places scattered across the Universe. It’s just that they are so far apart they are forever isolated from each other.

What makes a planet ‘lucky’?It’s not that any single property is rare; it’s the combination of many slightly unusual properties. If one in 10 planets are the right size and one in 10 planets orbit at the right distance and one in 10 planets have the right amount of water… you can see where I’m going with this. What do you think about the latest exoplanet searches?Despite all I’ve said, I’m a huge supporter of the ongoing hunt for exoplanets. I think the data we have at present points to habitable worlds being rare, but that’s based on very little data. What we need is more information, which will hopefully prove my pessimism to be misplaced.

Dr DavID WalTham is a lecturer in mathematical geology at Royal Holloway

You can order these books from our shop by calling 01803 865913

reader price £13.99, subscriber price £12.99P&P £1.99 Code: S0414/2

David WalthamIcon £14.99 PB

Earth is exceptional. It is a planet that has

endured around four billion years of good

weather, purely by chance – the luckiest

planet in the visible Universe.

This is the argument of Lucky Planet,

written by University of London geophysicist

David Waltham. Many scientists dismiss

the idea that Earth is special; they favour

suggestions our home is actually mediocre

and that life is widespread throughout

the Universe. As the title suggests,

Waltham disagrees, detailing the many

ways in which Earth has just been very

fortunate indeed.

It is a refreshing angle amid

numerous similar titles

touting the opposing

view. Waltham explores

the various properties

our planet possesses

that have led to

its habitability,

covering astronomy,

biology, cosmology,

climatology,

and geology.

The most interesting

and important consideration

is that in order for Earth to be

how it is now, our planet must

have been potentially habitable

for a very large portion of its history.

While this may seem obvious, it is actually

quite an intriguing perspective – if the

Earth had had slightly more changeable

weather or a marginally different

atmospheric composition at any one

point, it would be an entirely different

planet today.

When it comes to structure, however,

the book is a little unusual. For example,

Waltham focuses for an oddly long time

on climatology and ice ages, and then

moves abruptly on to the idea of music,

later linking this with planetary orbits.

Some of the chapters could perhaps be best

expressed via a timeline, as embedding

copious details about

atmosphere, temperature

and feedback processes

at various stages in

Earth’s history into

dense paragraphs

of text is quite

diffcult to digest.

Although Lucky

Planet contains

several brilliant

analogies and

explanations, at times it

is obvious that Waltham is

a scientist frst and an author

second, as there is a tendency to

cram in technical information

at the expense of readability. However, if

you wish to learn about the climatology of

our planet from its formation to the present

day, it serves as a comprehensive overview.

★★★★★

NICkY GUTTrIDGE is a science journalist and Hubble public information offcer

New astronomy and space titles reviewed

Minute changes could have rendered Earth a very different place

Lucky Planet

110


BooksRATINGS

★★★★★ Outstanding ★★★★★ Good ★★★★★ Average★★★★★ Poor★★★★★ Avoid

Two minuTes

wiTh DaviD

walTham

What inspired you to write the book?Ten years ago it occurred

to me that the simple question ‘Is Earth an unusual planet?’ brought my passions of astronomy and geology together. We can’t understand Earth properly without answering this question and we can’t do that without looking at how our world fts into the wider Universe.

Do you think life has evolved elsewhere?Defnitely. The basic idea behind Lucky Planet is that the Universe is so large that even very odd places like Earth are inevitable. I think Earth is so rare that we’re unlikely to ever fnd another world with a biosphere as complex as ours; the fip side of this argument is that there are probably many such places scattered across the Universe. It’s just that they are so far apart they are forever isolated from each other.

What makes a planet ‘lucky’?It’s not that any single property is rare; it’s the combination of many slightly unusual properties. If one in 10 planets are the right size and one in 10 planets orbit at the right distance and one in 10 planets have the right amount of water… you can see where I’m going with this. What do you think about the latest exoplanet searches?Despite all I’ve said, I’m a huge supporter of the ongoing hunt for exoplanets. I think the data we have at present points to habitable worlds being rare, but that’s based on very little data. What we need is more information, which will hopefully prove my pessimism to be misplaced.

Dr DavID WalTham is a lecturer in mathematical geology at Royal Holloway

You can order these books from our shop by calling 01803 865913

reader price £13.99, subscriber price £12.99P&P £1.99 Code: S0414/2

David WalthamIcon £14.99 PB

Earth is exceptional. It is a planet that has

endured around four billion years of good

weather, purely by chance – the luckiest

planet in the visible Universe.

This is the argument of Lucky Planet,

written by University of London geophysicist

David Waltham. Many scientists dismiss

the idea that Earth is special; they favour

suggestions our home is actually mediocre

and that life is widespread throughout

the Universe. As the title suggests,

Waltham disagrees, detailing the many

ways in which Earth has just been very

fortunate indeed.

It is a refreshing angle amid

numerous similar titles

touting the opposing

view. Waltham explores

the various properties

our planet possesses

that have led to

its habitability,

covering astronomy,

biology, cosmology,

climatology,

and geology.

The most interesting

and important consideration

is that in order for Earth to be

how it is now, our planet must

have been potentially habitable

for a very large portion of its history.

While this may seem obvious, it is actually

quite an intriguing perspective – if the

Earth had had slightly more changeable

weather or a marginally different

atmospheric composition at any one

point, it would be an entirely different

planet today.

When it comes to structure, however,

the book is a little unusual. For example,

Waltham focuses for an oddly long time

on climatology and ice ages, and then

moves abruptly on to the idea of music,

later linking this with planetary orbits.

Some of the chapters could perhaps be best

expressed via a timeline, as embedding

copious details about

atmosphere, temperature

and feedback processes

at various stages in

Earth’s history into

dense paragraphs

of text is quite

diffcult to digest.

Although Lucky

Planet contains

several brilliant

analogies and

explanations, at times it

is obvious that Waltham is

a scientist frst and an author

second, as there is a tendency to

cram in technical information

at the expense of readability. However, if

you wish to learn about the climatology of

our planet from its formation to the present

day, it serves as a comprehensive overview.

★★★★★

NICkY GUTTrIDGE is a science journalist and Hubble public information offcer

New astronomy and space titles reviewed

Minute changes could have rendered Earth a very different place

Lucky Planet

books APRIL 111


Wizards, Aliens and Starships Charles l adler Princeton £19.95 PB

Fans of science-fction

and fantasy tales

usually realise that

they need to suspend

belief and allow

some poetic licence

so that a story may

be told. While

a few authors

try hard to keep

their narratives

within the bounds of scientifc possibility,

others seem to make up new laws of

physics as they go along.

Wizards, Aliens and Starships looks

at many of the common concepts and

plot devices that are used in science

fction and examines the actual science

behind them. There’s a hefty chunk

dealing with the fantasy world of Harry

Potter to get past, but from there on

the book concerns itself with topics

of greater interest to astronomers and

space fans. How easy is it really to travel

vast distances in space, for instance?

What propulsion systems could be used?

What are the practicalities of founding

colonies and terraforming planets?

Will we ever travel faster than light?

What are the chances of fnding and

communicating with ET?

These are just a few of the range of

topics examined by author and professor

of Physics Charles Adler. He says this is

the book he would have wanted to read

as a 15-year-old boy, but offers a word of

warning: that readers should have some

knowledge of algebra and calculus; and

indeed there are many formulae and

equations scattered throughout the

book. Despite this, the writing style is

light and will give sci-f fans a rewarding

and thought-provoking read.

★★★★★

PaUl SUThErlaND is a space writer and journalist

reader price £14.95, subscriber price £13.95 P&P £1.99 Code: S0414/1

Omar W Nasim Chicago £31.50 hB

As befts its subject

matter, Observing by

Hand looks beautiful.

It deals with the

tricky, rather

under-researched

area of observational

astronomy, that

place between

observation and publication. Author Omar

Nasim uses tools from art history as well

as a good understanding of astronomy to

explore this complicated relationship

between art and science; between the eye,

the mind and the hand; between what is

observed and the image produced.

Today astronomy is intertwined with

photography. For a signifcant part of the

19th century, images were produced by hand,

requiring artistic skill, an understanding

of the heavens and an ability to record

detail accurately and quickly. The style of

writing refects the content, being careful

and meticulous, just as the observers were

who produced the images discussed.

Each chapter focuses on different

astronomers and how their approach to

drawing nebulae adds to the bigger story.

Through the work of Lord Rosse and his

assistants John Herschel, EP Mason, William

Lassell and Wilhelm Tempel, we see the

range of techniques used, and the factors

that shaped them. In doing so, Nasim

shows us the role theory played in shaping

what each astronomer saw, the skill

involved in ‘translating’ that onto paper,

and the fuidity of the border between art

and science. For anyone with an interest

and appreciation of the beauty of nebulae,

this is a book that will leave you thinking.

★★★★★

Dr EmIlY WINTErBUrN is a writer and visiting fellow at the University of Leeds


John Bromley-Davenport Bene Factum Publishing£20 hB

Sir Bernard lovell was one of the most eminent British scientists of the past hundred years. a pioneer of radar techniques, originator of Jodrell Bank

Observatory and a popular orator of the physical sciences, his legacy is immense.

This biography by family friend John Bromley-Davenport, coming little more than a year after lovell’s death, is an insightful and detailed account of the astronomer’s life. Using carefully researched original documents, and peppered with personal anecdotes from lovell himself, Bromley-Davenport gives a fascinating profle of the man, his science, his beliefs, and his trials and tribulations.

although many of the basic details of lovell’s life are available elsewhere, this offering digs a little deeper into some of the major events of his life. The account of lovell’s wartime radar development is excellent, flling in hitherto unpublished details. The stresses and strains during the design and construction of the 76m radio telescope at Jodrell Bank that bears lovell’s name are ably portrayed. lovell’s involvement with certain secretive aspects of the Cold War are well known, but this account contains new facts based on recently released offcial records.

The assertion that lovell was duped by a committed marxist into believing he was an undercover government agent seems both incongruous and speculative. So too is the inference that lovell himself was a spy. Nevertheless, this biography is a fascinating and scholarly read.★★★★★

Dr alaSTaIr GUNN is a radio astronomer at Jodrell Bank Observatory in Cheshire


Space Has No FrontierThe Terrestrial Life and Times of Sir Bernard Lovell

Observing by Hand Sketching the Nebulae in the 19th Century

book oF The monTh

books APRIL 111


Wizards, Aliens and Starships Charles l adler Princeton £19.95 PB

Fans of science-fction

and fantasy tales

usually realise that

they need to suspend

belief and allow

some poetic licence

so that a story may

be told. While

a few authors

try hard to keep

their narratives

within the bounds of scientifc possibility,

others seem to make up new laws of

physics as they go along.

Wizards, Aliens and Starships looks

at many of the common concepts and

plot devices that are used in science

fction and examines the actual science

behind them. There’s a hefty chunk

dealing with the fantasy world of Harry

Potter to get past, but from there on

the book concerns itself with topics

of greater interest to astronomers and

space fans. How easy is it really to travel

vast distances in space, for instance?

What propulsion systems could be used?

What are the practicalities of founding

colonies and terraforming planets?

Will we ever travel faster than light?

What are the chances of fnding and

communicating with ET?

These are just a few of the range of

topics examined by author and professor

of Physics Charles Adler. He says this is

the book he would have wanted to read

as a 15-year-old boy, but offers a word of

warning: that readers should have some

knowledge of algebra and calculus; and

indeed there are many formulae and

equations scattered throughout the

book. Despite this, the writing style is

light and will give sci-f fans a rewarding

and thought-provoking read.

★★★★★

PaUl SUThErlaND is a space writer and journalist


Omar W Nasim Chicago £31.50 hB

As befts its subject

matter, Observing by

Hand looks beautiful.

It deals with the

tricky, rather

under-researched

area of observational

astronomy, that

place between

observation and publication. Author Omar

Nasim uses tools from art history as well

as a good understanding of astronomy to

explore this complicated relationship

between art and science; between the eye,

the mind and the hand; between what is

observed and the image produced.

Today astronomy is intertwined with

photography. For a signifcant part of the

19th century, images were produced by hand,

requiring artistic skill, an understanding

of the heavens and an ability to record

detail accurately and quickly. The style of

writing refects the content, being careful

and meticulous, just as the observers were

who produced the images discussed.

Each chapter focuses on different

astronomers and how their approach to

drawing nebulae adds to the bigger story.

Through the work of Lord Rosse and his

assistants John Herschel, EP Mason, William

Lassell and Wilhelm Tempel, we see the

range of techniques used, and the factors

that shaped them. In doing so, Nasim

shows us the role theory played in shaping

what each astronomer saw, the skill

involved in ‘translating’ that onto paper,

and the fuidity of the border between art

and science. For anyone with an interest

and appreciation of the beauty of nebulae,

this is a book that will leave you thinking.

★★★★★

Dr EmIlY WINTErBUrN is a writer and visiting fellow at the University of Leeds


John Bromley-Davenport Bene Factum Publishing£20 hB

Sir Bernard lovell was one of the most eminent British scientists of the past hundred years. a pioneer of radar techniques, originator of Jodrell Bank

Observatory and a popular orator of the physical sciences, his legacy is immense.

This biography by family friend John Bromley-Davenport, coming little more than a year after lovell’s death, is an insightful and detailed account of the astronomer’s life. Using carefully researched original documents, and peppered with personal anecdotes from lovell himself, Bromley-Davenport gives a fascinating profle of the man, his science, his beliefs, and his trials and tribulations.

although many of the basic details of lovell’s life are available elsewhere, this offering digs a little deeper into some of the major events of his life. The account of lovell’s wartime radar development is excellent, flling in hitherto unpublished details. The stresses and strains during the design and construction of the 76m radio telescope at Jodrell Bank that bears lovell’s name are ably portrayed. lovell’s involvement with certain secretive aspects of the Cold War are well known, but this account contains new facts based on recently released offcial records.

The assertion that lovell was duped by a committed marxist into believing he was an undercover government agent seems both incongruous and speculative. So too is the inference that lovell himself was a spy. Nevertheless, this biography is a fascinating and scholarly read.★★★★★

Dr alaSTaIr GUNN is a radio astronomer at Jodrell Bank Observatory in Cheshire


Space Has No FrontierThe Terrestrial Life and Times of Sir Bernard Lovell

Observing by Hand Sketching the Nebulae in the 19th Century

book oF The monTh

1

2

4


Elizabeth Pearson rounds up the latest astronomical accessories

Gear112 GEAR APRIL

5

63

1 Orion Newtonian Visual Centering Device

Price £139 • Supplier SCS Astro0800 0181544 • www.scsastro.co.uk

Designed for use with Newtonian refectors, this device allows you to centre your imaging target visually through its built-in eyepiece, rather than your camera’s screen or software.

2 Baader Classic Q-Eyepiece SetPrice £215 • Supplier The Widescreen Centre 020 7935 2580 • www.widescreen-centre.co.uk

The set includes four eyepieces, ranging from 6mm to 32mm, as well Baader’s Q-Turret, which slots into a telescope and allows you to switch between all four with ease. The set comes with a 2.25x Barlow lens.

3 Lacerta Newtonian Carry CasePrice From £72 • Supplier 365 Astronomy020 3384 5187 • www.365astronomy.com

Designed to transport and store Newtonian telescopes, this padded case helps keep your kit safe. Available in various sizes.

4 Celestron 9x50 Illuminated Right Angle Correct Image Finderscope

Price £112.99 • Supplier Harrison Telescopes01932 703605 • www.harrisontelescopes.co.uk

This fnderscope uses a dual crosshair, so you can centre objects without obscuring them. Its right-angled orientation makes it easy to use even when your scope is pointing at the zenith.

5 SmarTouch Chunky Knit Touchscreen GlovesPrice £15 • Supplier Totes01277 636802 • www.totes.co.uk

Conductive material in the fngertips promises to let you to carry on using touchscreen devices during cold observing sessions without the need to take your gloves off – smart indeed.

6 Lego Curiosity RoverPrice £24.99 • Supplier Lego00 800 5346 1111 • www.lego.com

Just like the real Curiosity rover, this Lego replica is capable of tackling a variety of terrains thanks to its rocker-bogie suspension system.

1

2

4


Elizabeth Pearson rounds up the latest astronomical accessories

Gear112 GEAR APRIL

5

63

1 Orion Newtonian Visual Centering Device

Price £139 • Supplier SCS Astro0800 0181544 • www.scsastro.co.uk

Designed for use with Newtonian refectors, this device allows you to centre your imaging target visually through its built-in eyepiece, rather than your camera’s screen or software.

2 Baader Classic Q-Eyepiece SetPrice £215 • Supplier The Widescreen Centre 020 7935 2580 • www.widescreen-centre.co.uk

The set includes four eyepieces, ranging from 6mm to 32mm, as well Baader’s Q-Turret, which slots into a telescope and allows you to switch between all four with ease. The set comes with a 2.25x Barlow lens.

3 Lacerta Newtonian Carry CasePrice From £72 • Supplier 365 Astronomy020 3384 5187 • www.365astronomy.com

Designed to transport and store Newtonian telescopes, this padded case helps keep your kit safe. Available in various sizes.

4 Celestron 9x50 Illuminated Right Angle Correct Image Finderscope

Price £112.99 • Supplier Harrison Telescopes01932 703605 • www.harrisontelescopes.co.uk

This fnderscope uses a dual crosshair, so you can centre objects without obscuring them. Its right-angled orientation makes it easy to use even when your scope is pointing at the zenith.

5 SmarTouch Chunky Knit Touchscreen GlovesPrice £15 • Supplier Totes01277 636802 • www.totes.co.uk

Conductive material in the fngertips promises to let you to carry on using touchscreen devices during cold observing sessions without the need to take your gloves off – smart indeed.

6 Lego Curiosity RoverPrice £24.99 • Supplier Lego00 800 5346 1111 • www.lego.com

Just like the real Curiosity rover, this Lego replica is capable of tackling a variety of terrains thanks to its rocker-bogie suspension system.

What is life like on the ISS?

When you, a terrestrial human being,

go into space, you are faced with

the fact you are in a new

environment. You’re

there to work, and you want to work,

but frst of all you need to adapt

yourself. You fnd yourself

in a new place where there is

no gravity, and you have to

learn everything from

scratch. You need to

become an

extraterrestrial person.

It can be extremely

frustrating, but it is

also very nice, a bit

like being a little kid

discovering new things.

Most days followed the

same routine. At 6am you

wake up, have breakfast,

clean up and do whatever you

need to be ready to start work

at 7.30am.

We spent about eight hours doing

scheduled work. If we had a shuttle

arriving or a space walk to complete there

would be a lot to do to prepare, but most of that

time we were taking care of the station or carrying

out scientifc experiments.

A lot of hard workRunning experiments could be psychologically

taxing. We had to train for so many things that we

might have learnt how to carry out a particular

experiment a year beforehand. A couple of times

I went to do something and I had no idea I had

even trained for that experiment. Some were very

repetitive and I was always sleep deprived, so

sometimes I fell asleep! The scientists were

measuring my response time in milliseconds, but

I was napping. When that happened, I’d feel stupid.

One thing that helped was doing exercise – I could

switch off and think about other things. It is very

important to keep your body up to par and lower

the negative effects of microgravity, but exercising

was also very relaxing. Two hours every day were

spent on physical ftness. There is a special treadmill

as well as a machine called the Advanced Resistive

Exercise Device, which lets you do weightlifting in

About PAoLo NESPoLI

Paolo Nespoli served as a fight engineer aboard the ISS as part of Expeditions 26 and 27. He frst travelled to space aboard Space Shuttle Discovery in 2007.

space – a place where there is no weight!

At 8pm we usually had a debriefng where we

could talk about what happened during the

day and get feedback. After that we had

an hour and a half before we went to

sleep at 10pm, and could do

whatever we wanted.

I spent most of my time

going through emails and

talking with my family.

The International Space

Station is a confned,

isolated place and I was

grateful that there was

a way to communicate.

Ground control realises

that you are a human

being, not a machine,

and they come up with all

sorts of tricks to make it

more bearable. One of them

is to make sure each

of the astronauts has their own

phone. You need to pay attention

and check the availability of the

satellite it transmits through, but once

you learn how to use it it’s just like any other

phone. I would call people to say hello and

I talked to my wife every day to let her know what

was going on up there.

One of things I would do every day was go

into the cupola, a room with 360° views out into

space, and just look at Earth as we passed by.

I took something like 26,000 pictures while I was

in space. At frst it’s not easy; in the beginning

Earth seen from space is just this blue ball. But

as you become an extraterrestrial person, you

develop this eye. You can just glimpse down

and you know where you are.

I hope this experience is something that

many people will be able to do in the future.

You learn a lot about yourself, about other

people and about Earth. Seeing our planet

from up there gives you a perspective and

understanding that is very different from

any you can get from the ground – I wish everybody

could share that. Now that I’m back down on

the planet, though, I like to say that I am still

the same guy that grew up in a small town in

the middle of nowhere.

114 EXPERT inTERviEw APRIL

na

sa

/e

sa


WHAT I REALLY WANT TO KNOW IS…

ESA astronaut Paolo Nespoli served as a fight engineer aboard the ISS from December 2010 to May 2011interviewed by eLiZAbetH PeArSOn

Nepsoli, right, was a prolifc photographer, taking 26,000 images

S

What is life like on the ISS?

When you, a terrestrial human being,

go into space, you are faced with

the fact you are in a new

environment. You’re

there to work, and you want to work,

but frst of all you need to adapt

yourself. You fnd yourself

in a new place where there is

no gravity, and you have to

learn everything from

scratch. You need to

become an

extraterrestrial person.

It can be extremely

frustrating, but it is

also very nice, a bit

like being a little kid

discovering new things.

Most days followed the

same routine. At 6am you

wake up, have breakfast,

clean up and do whatever you

need to be ready to start work

at 7.30am.

We spent about eight hours doing

scheduled work. If we had a shuttle

arriving or a space walk to complete there

would be a lot to do to prepare, but most of that

time we were taking care of the station or carrying

out scientifc experiments.

A lot of hard workRunning experiments could be psychologically

taxing. We had to train for so many things that we

might have learnt how to carry out a particular

experiment a year beforehand. A couple of times

I went to do something and I had no idea I had

even trained for that experiment. Some were very

repetitive and I was always sleep deprived, so

sometimes I fell asleep! The scientists were

measuring my response time in milliseconds, but

I was napping. When that happened, I’d feel stupid.

One thing that helped was doing exercise – I could

switch off and think about other things. It is very

important to keep your body up to par and lower

the negative effects of microgravity, but exercising

was also very relaxing. Two hours every day were

spent on physical ftness. There is a special treadmill

as well as a machine called the Advanced Resistive

Exercise Device, which lets you do weightlifting in

About PAoLo NESPoLI

Paolo Nespoli served as a fight engineer aboard the ISS as part of Expeditions 26 and 27. He frst travelled to space aboard Space Shuttle Discovery in 2007.

space – a place where there is no weight!

At 8pm we usually had a debriefng where we

could talk about what happened during the

day and get feedback. After that we had

an hour and a half before we went to

sleep at 10pm, and could do

whatever we wanted.

I spent most of my time

going through emails and

talking with my family.

The International Space

Station is a confned,

isolated place and I was

grateful that there was

a way to communicate.

Ground control realises

that you are a human

being, not a machine,

and they come up with all

sorts of tricks to make it

more bearable. One of them

is to make sure each

of the astronauts has their own

phone. You need to pay attention

and check the availability of the

satellite it transmits through, but once

you learn how to use it it’s just like any other

phone. I would call people to say hello and

I talked to my wife every day to let her know what

was going on up there.

One of things I would do every day was go

into the cupola, a room with 360° views out into

space, and just look at Earth as we passed by.

I took something like 26,000 pictures while I was

in space. At frst it’s not easy; in the beginning

Earth seen from space is just this blue ball. But

as you become an extraterrestrial person, you

develop this eye. You can just glimpse down

and you know where you are.

I hope this experience is something that

many people will be able to do in the future.

You learn a lot about yourself, about other

people and about Earth. Seeing our planet

from up there gives you a perspective and

understanding that is very different from

any you can get from the ground – I wish everybody

could share that. Now that I’m back down on

the planet, though, I like to say that I am still

the same guy that grew up in a small town in

the middle of nowhere.

114 EXPERT inTERviEw APRILn

as

a/e

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WHAT I REALLY WANT TO KNOW IS…

ESA astronaut Paolo Nespoli served as a fight engineer aboard the ISS from December 2010 to May 2011interviewed by eLiZAbetH PeArSOn

Nepsoli, right, was a prolifc photographer, taking 26,000 images

S


StarS and conStellationS

Leo is one of the few constellations

that looks like its namesake – but only

from the northern hemisphere. From down

under the Lion sits low in the north, but upside

down. Its head and shoulders are referred to

as the Sickle, with its top member Leo’s

brightest star, mag. +1.4 Regulus (Alpha (α)

Leonis). To the east lie its hindquarters,

consisting of a conspicuous triangle of stars.

This group’s brightest star is mag. +2.1

Denebola (Beta (β) Leonis): its name is short

for an Arabic phrase meaning ‘tail of the Lion’.

Teapot

TELESCO

SCORPIUS

SERPENS C

APU

TCO

RON

A BOREALIS

SERPENS CAUDA

OPH

IUC

HU

S

IND

SCUTUM

SAG

ITTARIU

S

CORONA

AUSTRALIS

HERC

ULES

αγδ

βγ

α

α

β

γ

γβ

α

δ

α

γ

δ

α

α

γδ

α

β

γ α

β δ

M16

M17

M20

M8

M12

M10

M19 M

62

M28

M22

M7

M6

M23

M25

Peacock

20th

NORTHEAST

EA

ST

SOUTHEAST

> 1 April 00:00 > 15 April 23:00 > 30 April 22:00

WHen to USe tHiS cHartThe chart accurately matches the sky on the dates and times shown. The sky is different at other times as stars crossing it set four minutes earlier each night. We’ve drawn the chart for latitude –35° south.

SoUtHern HeMiSPHere in aPril With Glenn Dawes

aPril HigHligHtS

A total lunar eclipse will be visible from

eastern Australia on 15 April. Mid-

eclipse is around moonrise in the evening

twilight: a good time to observe would be just

before totality ends at 18:24 EST. From central

Australia totality ends before moonrise, with

Western Australia missing all of the eclipse.

The afternoon of 29 April brings an annular

eclipse of the Sun with partial phases visible

across Australia. Maximum eclipse is

around 17:00 EST from the eastern states

and 15:00 EST from Western Australia.

Mars transits the meridian around

midnight and is visible the entire night.

Being at opposition, it reaches its brightest

(mag. –1.5) and maximum angular size

(15.2 arcseconds) during the month. Brilliant

Jupiter is in the northwest evening sky,

setting around 23:00 EST. The evenings also

offer Saturn, which arrives just after twilight

and is due north in the early morning. Venus

dominates the morning sky, rising around

3:00 EST, with Mercury briefy visible low in

the eastern dawn sky for the frst week of April.

tHe PlanetS

Autumn is a great time to observe

galaxies, one particularly remarkable

collection being Markarian’s Chain:

seven galaxies arranged in an

arc 1.5° long and visible in

6-inch scopes. The western

end is marked by mag.

+9.1 elliptical galaxy M84

(RA 12h 25.0m, dec. +12°

53’), pictured. It has a

3-arcminute circular core,

brighter but smaller than the

next member 16 arcminutes east,

M86. Journeying another 22 arcminutes

takes you to galaxy pair NGC 4435/4438.

The chain continues northeast

with the fainter NGC 4461,

NGC 4473 and NGC 4477.

Open cluster Melotte

111 (RA 12h 25.1m,

dec. +26° 06’) in Coma

Berenices is best seen with

binoculars. This scattered

group of 5th- to 8th-magnitude

stars is around 2° in diameter.

deeP-Sky objectS

NO

AO

/AU

RA

/NSF

GALAXY

OPEN CLUSTER

GLOBULAR

CLUSTER

PLANETARY

NEBULA

DIFFUSE

NEBULOSITY

DOUBLE STAR

VARIABLE STAR

COMET TRACK

ASTEROID

TRACK

METEOR

RADIANT

QUASAR

STAR

BRIGHTNESS:

MAG. 0

& BRIGHTER

MAG. +1

MAG. +2

MAG. +3

MAG. +4

& FAINTERPLANET

cHart key


StarS and conStellationS

Leo is one of the few constellations

that looks like its namesake – but only

from the northern hemisphere. From down

under the Lion sits low in the north, but upside

down. Its head and shoulders are referred to

as the Sickle, with its top member Leo’s

brightest star, mag. +1.4 Regulus (Alpha (α)

Leonis). To the east lie its hindquarters,

consisting of a conspicuous triangle of stars.

This group’s brightest star is mag. +2.1

Denebola (Beta (β) Leonis): its name is short

for an Arabic phrase meaning ‘tail of the Lion’.

Teapot

TELESCO

SCORPIUS

SERPENS C

APU

TCO

RON

A BOREALIS

SERPENS CAUDA

OPH

IUC

HU

S

IND

SCUTUM

SAG

ITTARIU

S

CORONA

AUSTRALIS

HERC

ULES

αγδ

βγ

α

α

β

γ

γβ

α

δ

α

γ

δ

α

α

γδ

α

β

γ α

β δ

M16

M17

M20

M8

M12

M10

M19 M

62

M28

M22

M7

M6

M23

M25

Peacock

20th

NORTHEAST

EA

ST

SOUTHEAST

> 1 April 00:00 > 15 April 23:00 > 30 April 22:00

WHen to USe tHiS cHartThe chart accurately matches the sky on the dates and times shown. The sky is different at other times as stars crossing it set four minutes earlier each night. We’ve drawn the chart for latitude –35° south.

SoUtHern HeMiSPHere in aPril With Glenn Dawes

aPril HigHligHtS

A total lunar eclipse will be visible from

eastern Australia on 15 April. Mid-

eclipse is around moonrise in the evening

twilight: a good time to observe would be just

before totality ends at 18:24 EST. From central

Australia totality ends before moonrise, with

Western Australia missing all of the eclipse.

The afternoon of 29 April brings an annular

eclipse of the Sun with partial phases visible

across Australia. Maximum eclipse is

around 17:00 EST from the eastern states

and 15:00 EST from Western Australia.

Mars transits the meridian around

midnight and is visible the entire night.

Being at opposition, it reaches its brightest

(mag. –1.5) and maximum angular size

(15.2 arcseconds) during the month. Brilliant

Jupiter is in the northwest evening sky,

setting around 23:00 EST. The evenings also

offer Saturn, which arrives just after twilight

and is due north in the early morning. Venus

dominates the morning sky, rising around

3:00 EST, with Mercury briefy visible low in

the eastern dawn sky for the frst week of April.

tHe PlanetS

Autumn is a great time to observe

galaxies, one particularly remarkable

collection being Markarian’s Chain:

seven galaxies arranged in an

arc 1.5° long and visible in

6-inch scopes. The western

end is marked by mag.

+9.1 elliptical galaxy M84

(RA 12h 25.0m, dec. +12°

53’), pictured. It has a

3-arcminute circular core,

brighter but smaller than the

next member 16 arcminutes east,

M86. Journeying another 22 arcminutes

takes you to galaxy pair NGC 4435/4438.

The chain continues northeast

with the fainter NGC 4461,

NGC 4473 and NGC 4477.

Open cluster Melotte

111 (RA 12h 25.1m,

dec. +26° 06’) in Coma

Berenices is best seen with

binoculars. This scattered

group of 5th- to 8th-magnitude

stars is around 2° in diameter.

deeP-Sky objectS

NO

AO

/AU

RA

/NSF

GALAXY

OPEN CLUSTER

GLOBULAR

CLUSTER

PLANETARY

NEBULA

DIFFUSE

NEBULOSITY

DOUBLE STAR

VARIABLE STAR

COMET TRACK

ASTEROID

TRACK

METEOR

RADIANT

QUASAR

STAR

BRIGHTNESS:

MAG. 0

& BRIGHTER

MAG. +1

MAG. +2

MAG. +3

MAG. +4

& FAINTERPLANET

cHart key

SoUtHern HeMiSPHere


Celestial Equator

Ecliptic

Sickle

Kite

Winter Triangle

FalseCross

CANIS MIN

OR

MO

NO

CERO

SCA

NIS

MAJ

OR

OCTANS

TUCANA

HYDRUSRETICULUM

DORADO

PICTOR

COLUMBA

PUPP

IS

CARINA

VELA

VOLANS

APUS

PAVO

TRIANGULU

M

AUSTRA

LE

CIRCINUS

MUSCA

CENTAURUS

CRUX

CHAMAELEON

ARA

PYXI

S

MEN

SA

CA

NC

ER

HYDRA

LEO

South Celestial Pole

CORVUS

LYNX

CRATER

VIRGO

LUPUS

URSAMAJOR

LEO MINORCOMA

BERENICES

NO

RMA

AN

TLIA

LIBRA

BOÖTES CANES VENATICI

ELESCOPIUM

SCORPIUS

SERP

INDUS

RONARALIS

Markarian’s

Chain

Melotte 111

α

β

δγ

β

α

α

β

α

γβ

δ

α

β γ

α

β

γ

αδ

β

δ

α

γ

α

β

δ

β

γ

α

δ

δ γ

αβγ

β

α

δ

α

β

δ

γ

β

δ

α

β

δγ

β

α

α

δβ

α

γ

δ

β

α

δ γ

γ

δ

β βα

δ

γ

α

γβ

δ

α

β

δ

γ

α

γ

βδ

αβ

γ δ

δγ

β α

α

δ

γ

β

γ

β

α

δ

α

βα

β

γ δ

α

γδβ

γδ

β

α

β γ

αδ

δ

β

α

γ

β

δ

β

α

δ

α

γβ

δ

αβ

δ

γ

δ

β

γ

α

αγ

β

R

R

υ

εb

ι

Saturn

Mars 30th1st

Tarantula Nebula

M5

M

M4

ω C

en

47 Tuc

M3

M44

M48

M47

M41

Jewe

l Box

Coal Sack

NG

C 3195

M93

LMC

SMC

Cen A

M83

M104Leo Triplet

M60 M87

M86

M64

M94M63

M51 M106

M84

Ghost of Jupiter

Rigel Kent

Acherna

r

Canopus

Sirius

Acr

ux

Procyon

Alm

ach

Alphard

Hadar

Regulus

Spica

Arcturus

Cor Caroli

Antares

Peacock Star

Den

ebol

a

8th

11th

14th

17th

NORTH

SOUTH

SOUTH

WES

T

WES

T

N

ORTHW

EST

SoUtHern HeMiSPHere


Celestial Equator

Ecliptic

Sickle

Kite

Winter Triangle

FalseCross

CANIS MIN

OR

MO

NO

CERO

SCA

NIS

MAJ

OR

OCTANS

TUCANA

HYDRUSRETICULUM

DORADO

PICTOR

COLUMBA

PUPP

IS

CARINA

VELA

VOLANS

APUS

PAVO

TRIANGULU

M

AUSTRA

LE

CIRCINUS

MUSCA

CENTAURUS

CRUX

CHAMAELEON

ARA

PYXI

S

MEN

SA

CA

NC

ER

HYDRA

LEO

South Celestial Pole

CORVUS

LYNX

CRATER

VIRGO

LUPUS

URSAMAJOR

LEO MINORCOMA

BERENICES

NO

RMA

AN

TLIA

LIBRA

BOÖTES CANES VENATICI

ELESCOPIUMSCO

RPIUS

SERP

INDUS

RONARALIS

Markarian’s

Chain

Melotte 111

α

β

δγ

β

α

α

β

α

γβ

δ

α

β γ

α

β

γ

αδ

β

δ

α

γ

α

β

δ

β

γ

α

δ

δ γ

αβγ

β

α

δ

α

β

δ

γ

β

δα

β

δγ

β

α

α

δβ

α

γ

δ

β

α

δ γ

γ

δ

β βα

δ

γ

α

γβ

δ

α

β

δ

γ

α

γ

βδ

αβ

γ δ

δγ

β α

α

δ

γ

β

γ

β

α

δ

α

βα

β

γ δ

α

γδβ

γδ

β

α

β γ

αδ

δ

β

α

γ

β

δ

β

α

δ

α

γβ

δ

αβ

δ

γ

δ

β

γ

α

αγ

β

R

R

υ

εb

ι

Saturn

Mars 30th1st

Tarantula Nebula

M5

M

M4

ω C

en

47 Tuc

M3

M44

M48

M47

M41

Jewe

l Box

Coal Sack

NG

C 3195

M93

LMC

SMC

Cen A

M83

M104

Leo Triplet

M60 M87

M86

M64

M94M63

M51 M106

M84

Ghost of Jupiter

Rigel Kent

Acherna

r

Canopus

Sirius

Acr

ux

Procyon

Alm

ach

Alphard

Hadar

Regulus

Spica

Arcturus

Cor Caroli

Antares

Peacock Star

Den

ebol

a

8th

11th

14th

17th

NORTH

SOUTH

SOUTH

WES

T

WES

T

N

ORTHW

EST

Sky at Night - April 2014

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Transcript of Sky at Night - April 2014