Ingemar Nordgren: Possible origin of the Goths traced through the symbolism of the ring...
Introduction to Astronomy: Size Scales & Taxonomy Acknowledgements Tyler Nordgren & Julie Rathbun...
-
Upload
harold-dawson -
Category
Documents
-
view
221 -
download
2
Transcript of Introduction to Astronomy: Size Scales & Taxonomy Acknowledgements Tyler Nordgren & Julie Rathbun...
Introduction to Introduction to Astronomy: Astronomy:
Size Scales & Size Scales & TaxonomyTaxonomy
Acknowledgements Tyler Nordgren & Julie Rathbun (University of Redlands)Lynne Raschke, Anne Metevier, Scott Seagroves, & Scott Severson (UCSC)
Photo credit: Roger Smith/NOAO/AURA/NSF
Kathy Cooksey
Assignments
• APOD Presentations: July 10 Demo – http://antwrp.gsfc.nasa.gov/apod/ap07071
0.html
• Astronomy Challenge– With every assignment comes a gift…
introduce planisphere– Due Friday July 20– Come to class with questions!! Please!– I’m free for study hall sessions
The Universe …
… from the Solar System…
… to the Stars…
… to the Milky Way …
… and beyond.
• How well do you know your own neighborhood?
• Imagine we shrink our solar system down to the scale where our Sun were the size of a volleyball:
– How big would the Earth be?– How far from the Sun would the Earth be?– How about Jupiter?
Size Scales
Concept Question
What are the sizes of the planets if the Sun were 8” in diameter?
Powers of Ten
QuickTime™ and aCinepak decompressor
are needed to see this picture.
Powers of Homer
D’oh!
Distance Units in Astronomy
• Astronomical Unit– Distance between Earth and Sun– 1 AU = 93 million miles = 150 million km
• Light-year– Distance light travels in one year– Light travels at velocity of 186,000 miles /
second– 1 l-y = 6 trillion miles = 9.5 trillion km
When we observe an object that is 900 light-years away, we see it as it was 900 years ago
One More Distance Unit …
• Parsec– Distance to object
with parallax angle of one arcsecond
– Parallax angle = half of star’s apparent shift in sky when viewed two times, six months apart
– Arcsecond = 1/3600 of degree
– 1 parsec = 3.3 l-y
A Tour of the Universe
The Solar System
An Inventory
What is the Solar System?• Sun and system of objects orbiting Sun• What’s in the Solar System?
One Star
Eight Planets
Dozens of moons
Thousands of asteroids
Trillions of comets
Concept Question
What causes the moon to go through phases?
The Sun, Earth, and Moon
Moon phases are caused by relative positions of Sun, Earth, and Moon
Solar Eclipse
• Sometimes Moon passes between Sun and Earth
• Casts shadow on the Earth
Lunar Eclipse
• Earth passes between Sun and Moon• Earth casts shadow on Moon
Plane of Solar System
• Sun, Earth, and planets all lie in same plane
Planets
• First step to studying planets?– Compare and
contrast
• What are important qualities?
Terrestrial Planets
• Closest to Sun• Small
– Mass– Radius
• High density– Primarily rocky– Solid surface
• Few moons• No rings
Mercury
Venus
Earth
Mars
Jovian Planets
• Far from Sun• Large
– Mass– Radius
• Low density– Primarily gaseous– No solid surface
• Many moons• Many rings
Jupiter
Saturn
Uranus
Neptune
Dwarf Planets
• Eris– 27% larger than Pluto
• Twice as far
• Pluto– 19% radius of Earth
(743 mi)• 40 AU (30-49 AU)
• Ceres– 18% smallerthan
Pluto• 2.8 AU (Asteroid Belt)
Pluto: Eliot Young, APOD 3 Sep 2006
Eris: Keck Observatory, APOD 18 Sep 2006
Ceres: NASA, ESA, APOD 21 Aug 2006
Rings
• Jupiter’s four largest moons
• Similar in size to our moon
• Visible with binoculars
Galilean Moons
Io
Europa
Ganymede
Callisto
Scale Model of the Solar System
Everyone up and out the door…
THE SUNTHE SUN
The Closest Star
Sunspots
• Appear in photosphere
• 11-year sunspot cycle
• Center = Umbra• Edge =
Penumbra
Sunspots
SO
HO
Im
ag
es
20
01
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Solar Flare
Aurora
The Stars
The Solar Neighborhood
The nearest star, Alpha Centauri, is 4.4 light-years away!
Binary Stars
• Most stars in sky are in multiple systems that orbit each other.
• Binaries, triplets, quadruplets, etc…
• Sun is single star--unusual!
Stellar Sizes
Supergiants, Giants, and Dwarfs
Star clusters
Open Clusters
• Loose collection of stars
• Tens to over hundred stars
• Young stars
Globular Clusters
• Spherical shape• Hundreds of
thousands of stars
• Old stars
Interstellar MediumInterstellar Medium
The Stuff Between Stars
Distribution• Picture dust under your bed
– Fairly uniform thin layer– Some small clumps– Occasional big complexes
• Interstellar dust and gas is same
Dark Nebulae
• Dust blocks some light
Copyright: AURA
Reflection Nebulae
• Blue light is scattered by dust.
NGC 1788, Kathy Cooksey
Witchhead Nebula
Emission Nebulae
• Some gas clouds shine because they are heated by young hot stars within them
Lagoon nebula Copyright - Jason Ware
M57 – Ring Nebula Cat’s Eye
Eskimo Nebula Hourglass Nebula
Planetary Nebulae• Clouds of gas thrown off when star stops
burning
Black Holes and Neutron Stars
Dead StarsCopyright – A. Hobart
Neutron Stars• Giant ball of neutrons• Mass : at least 1.4 x
mass of Sun• Diameter: 20 km!• Density: 1018 kg/m3
– Thimble full weighs as much as mountain
• Spin once every 0.0001 to 1 second• Magnetic fields as strong as Sun, but in
space of a city
Black Holes
• When high-mass star’s core is heavier than ~3 x Msun
– It collapses
– Density so high not even light escapes!
• Star collapses to form black hole
Black Holes• Light bent by
gravity of black hole
• Event horizon is boundary inside which even light cannot escape
• Near event horizon, time slows down relative to distant observers
Seeing Black Holes• Can’t see black hole
itself• Can see matter falling
into hole.• Gravitational forces
stretch and rip matter– Matter heats up
• Very hot objects emit in X-rays (e.g., interior of Sun)
• Cygnus X-1
Illustration Credit: M. Weiss
Galaxies
Optical emission from stars and nebulae
Milky Way
Near-Infrared stellar emission – copyright E. L. Wright and COBE
The Milky Way
Your are Here
Other Galaxies
Galaxies come in many shapes and sizes.Milky Way is fairly large, massive galaxy
Ellipticals• Huge• No gas• No dust• No young
stars• Nothing but
old stars.– Random
orbits
M 87 Copyright – Anglo-Australian Telescope
Board
Jets
Spirals
Spirals
• Like Milky Way• Disks and
bulge• Young stars
and old• Gas and dust• Stars forming• Stars dying M81 and M82 – Copyright R. Gendler
M63 Copyright – S. Miyazaki, Suburu
NGC1365 Copyright – VLT
M31 The Andromeda Galaxy Copyright – Jason Ware
NGC 891 – Copyright WIYN
NGC 891 – Copyright J.C. Barentine, NOAO
Irregulars
Galaxy Groups
Local Group
Gala
xy
Merg
ers
QuickTime™ and a decompressor
are needed to see this picture.
Patrik
Jon
sson
, UC
SC
Interacting Galaxies
M51 Copyright – Tony and Daphne Hallas
Interacting Galaxies
NGC4676: “The Mice” Copyright – ACS Science & Engineering Team, NASA
Interacting Galaxies
Seyfert’s Sextet Copyright – J. English (U. Manitoba), C. Palma (PSU), et al., NASA
Galaxy Clusters
Hubble Deep Field
Hubble Ultra Deep Field
One Last Trip...
Summary
• What new fact did you learn?– About the size of the Universe?– About what’s in the Universe?– About…?