1. Constellation
and
Galaxies
Credit Given to:
Ethan Vedder

2. Describe in writing (a few words) at least 10
different things going on in this painting
A tree
The Twins
A boat
The watcher
A playful
man The
A girl playing
mother
A woman
A shy
fishing A married
man
A puzzling The sisters couple
girl
The thief
The monkey?
A man smoking The big dog
The running dog

5. Constellations
 Greek, Arab, Egyptian, and
Babylonian constellations
 88 major ones (you don’t have to
know all of them)
 North Circumpolar
 Winter, spring, summer, fall
constellations
 Remember, these stars are only for
the Northern Hemisphere

6. Winter Constellations

7. Summer Constellations

8. Galaxies
http://www.galaxyphoto.com/high_res/hst_galaxy.JPG

9. Galaxies
 A large-scale group of stars
 100,000 light years across from one
side to the other
 100-400 billion stars per galaxy
 Thought to be between 50 billion and
1 trillion galaxies
 Quick math: 5,000,000,000,000,000,000
to 400,000,000,000,000,000,000
stars out there (5x1018-4x1020)

10. Galaxies
 Contain gas and dust (nebulae)
 Brought together by gravity
 Bright and dark nebulae
 “Local Group”: the 17 galaxies
within 3 million light years of the
Milky Way
 Closest
neighbors: Large and Small
Magellanic Clouds
 (a mere 150,000 light years away)

11. Types:
Spiral galaxies Elliptical galaxies Irregular galaxies
Huge; contain stars, Huge; contain stars, Huge; contain stars,
gas, and dust gas, and dust gas, and dust
Held together by gravity Held together by gravity Held together by gravity
Pinwheel shape (see Round-to-oval shape No regular shape
top view of Spiral 1,
above)
Bulge and thin disk; Bulge but no disk; halo May show signs of a
halo is present (see is present disk and/or a bulge;
side view of Spiral 2, halo is present
above)
Rich in gas and dust Little cool gas and dust Usually rich in gas and
dust
Young and old stars are Mainly old stars are Young and old stars are
present present present
http://amazing-space.stsci.edu/resources/organizers/galaxy.php.p=Astronomy+basics@eds.astronomy-basics.php

12. Spiral Galaxies
 Looks like a flattened disc
 Has a bulge/nucleus in the middle and
spiral arms on the outside
 Spiral arms contain dust and gas and
young stars
 Spiral (Sa, Sb, Sc) and,
 Barred Spiral (SBa, SBb, SBc)
 Ex. The Milky Way Galaxy
A barred spiral galaxy

13. Spiral Galaxy (Sa-Sc)
The Whirlpool Galaxy and its companion
http://en.wikipedia.org/wiki/Image:Messier51_sRGB.jpg

14. Barred Spiral Galaxy (SBa-
SBc)
 There is a
straight “bar”
at the
beginning of
the galactic
arms
http://www.news.wisc.edu/newsphotos/images/Milky_Way_galaxy_sun05.jpg

15. Elliptical Galaxies
 Do not have “arms”, instead look like
ellipses (flattened spheres)
 Symbols: E0-E7
 10-15% of known galaxies
 Are typically older stars and in the
center of globular clusters
 No gas and dust (likely the dust has
been used, collected, or blown away
by the stars already)

16. Elliptical Galaxies (E0-E7)
http://cseligman.com/text/stars/
http://csep10.phys.utk.edu/as messiergalaxies.htm
tr162/lect/galaxies/m87.gif

17. Irregular Galaxies
 These do not fit into spiral or elliptical
galaxy descriptions
 Believed to be spiral or elliptical
galaxies that were altered or distorted
by gravity
 Or galaxies that were too small to
organize themselves
 Generally small and faint
 25% of all galaxies

18. Computer models vs
Hubble Pictures

19. Irregular Galaxies
http://starchild.gsfc.nasa.g
ov/Images/StarChild/unive
rse_level2/ngc6822.gif
http://en.wikipedia.org/wiki/Image:G
alaxyNGC1427A_HubbleImage.jpg

21. The Milky Way Galaxy (us!)
 We are located on a spiral arm
 About 2/3 of the way out from the
center
 100,000 light years across

22. Star groups
 Stars
are more often found in
groups than by themselves
 We’re in the minority
 Open and Globular clusters
 Open = less, loose, galactic arms
 Globular = more, spherical, center
 Binary and triple star systems
 Revolve around each other

23. Quasars
 Some of the earliest things
produced from the big bang 13.7
billion years ago
 “Appear to be a faint small star”
with the energy output much
brighter than the brightest
galaxies…
 Howcan something be so small and
produce so much energy?

24. Star Journal Homework
 Go outside on a dark night with
no clouds
 Find a safe place that is pretty
dark (behind your house, a deck)
 Stay there for 10 minutes, but
DO NOT look at any bright lights
 Answer the questions on the
assignment sheet