How the Sky Moves

Evening Classes

Week One

Presented by Oisín Creaner

Course Outline

Week 1: The Sky

Week 2: The Planets

Week 3: The Stars

Week 4: History of Astronomy

Week 5: Telescopes

Week 6: Deep Sky Objects

– Week 7: Cosmology

Week 8: Alien Worlds

Basic Equipment

•Your eyes!

•Binoculars

•Books

•Planisphere

What can I see?

•Stars & Constellations

•The Planets (W2)

•Galaxies & Nebulae (W6)

•The Moon and Sun (CAREFUL!)

The night sky is like an up-turned bowl above theastronomer’s head.

a: Zenith

b: Meridian

c: Horizon

We can pretend thenight sky is a sphere,because all its starsare so far away fromus, they don’t appearto move at all.

The Celestial Sphere

The Celestial Sphere appears to spinbecause we see it from the surfaceof the spinning Earth.

Stars appear fixed on the Celestial Sphere.

The Plough

Polaris

Orion

Note the positions of –

•The Plough

•Polaris

•Orion

Celestial Coordinates

Declination is equivalent to latitiude and is measured in degrees.

Right Ascension is equivalent to longitude and is measured in hours, minutes and seconds.

Special Observation Locations

The View from Athlone - 53° North

Polaris stays in the same place –always directly North, 53° above the horizon.

Where you are on the Earth’s surface determineswhat constellations you can see, and how often.

Declination ofstars seen from Athlone

Circumpolar –90° N to 37° N

Seen sometimes –37°N - 37°S

Never seen – 37°S - 90°S

The ecliptic is where the Sun is seen againstthe Celestial Sphere.

The zodiac is a 16º wide band of sky wherethe planets are seen.

Ecliptic

γCel. Equator

The Sun crosses the celestial equator at the firstpoint of Aires, in the constellation Pisces.

This is the zero-point of the RA axis (0h 0m)

The Sun’s movement above & belowthe Celestial Equator

The track of the Sun across the Celestial Sphereis known as the Ecliptic.

Precession ofthe Equinoxes

The spinningEarth wobbles on its axis once every 26,000 years.

Using A Planisphere

PolarisTime

Date

Match the timewith the date

The Sky Window

Autumn Sky- October 10 p.m.

Since there are 12 months in the year, and 24 hours in the day, every month, an object will rise 2 hours earlier

Autumn Sky- Andromeda

Autumn Sky- Andromeda

Autumn Sky- Cygnus ‘The Swan’

Autumn Sky- Sagittarius ‘The Teapot’

Canis Major

Canis Minor

Gemini

Auriga

Taurus

Orion as a signpost

Thank You

www.astronomy.ie/handoutswww.stellarium.org

Useful websites