1. Galaxies

2. So, what is a Galaxy? A group of billions of stars, empty space,
gas & dust,
all held together by gravity!
Great web site of life cycle and hr diagram

3. This is a galaxy. This is a galaxy. This is a galaxy.
Great web site of life cycle and hr diagram
 This is a galaxy.
This is also a galaxy

4. Did you notice that all galaxies don’t look alike?
Click on picture for link!

5. elliptical shaped, no arms
Elliptical Galaxies
elliptical shaped, no arms
old stars very little gas & dust

6. Spiral galaxies (Milky Way)
disk shaped, lots of stars in center, arms wound around.
Middle age stars, lots of gas & dust

7. MORE Spiral galaxies …..

8. Barred spiral galaxies
disk shaped, arms wound around
young stars –lots of gas & dust

9. Irregular galaxies Lacks symmetry, not a lot of stars, mostly
gas & dust
Could have formed from:
the collision of two galaxies or
2) stars unable to organize

10. Collisions of galaxies… Irregular galaxies

11. The Milky Way Galaxy- Spiral Galaxy

12. Some Milky Way Facts.. Contains 100-400 billion stars
part of the local group- 28 closest galaxies within 3 million light years
the closest galaxy to us is 150,000
light years away

13. The Milky Way Galaxy
The arms of the galaxy orbit the nucleus once every 200 million years.

14. The Milky Way Galaxy
Our sun is 2/3 of the way out in one of the spiral arms.

15. 100,000 light-years across 10,000 light-years thick (center) 3,000 light-years on the edge