1. Galaxies
19.3

2. Elliptical Galaxies
Galaxies that have flat roundish shapes like a football
Contain billions of stars but have little gas and dust.
Contain mature or old stars – not new ones

3. Irregular Galaxies Do not have regular shapes
Typically smaller than other galaxy shapes
Have many bright young stars
Have lots of gas and dust to form new stars

4. Spiral Galaxies
Appear to have a bulge of stars in the center and arms that spiral outward
There are some that have a bar through the bulge with arms spiraling outward from the bar – barred-spiral galaxy
Bulge contains densely packed older stars but little gas and dust.
Outer arms contain younger stars and nebulae for more stars to form

5. Milky Way
Our solar system is in a spiral galaxy called the Milky Way, two thirds of the way out one arm
Recent evidence suggests that the Milky Way may be a barred- spiral galaxy
From the side it looks like a narrow disk with a bulge in the middle
From the top or bottom viewpoint the spiral shape is visible.
The center of our galaxy is about 25,000 light years away from us.