Galaxies 19.3

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

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

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

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.