Galaxies
Galaxies are clusters of billions of stars that are held together by gravity. Galaxies may have different shapes. There are three main types of galaxies.
Spiral Galaxies:
Spiral galaxies have a bulge in the middle and arms that spiral outward. These arms contain young stars and dust. The Milky Way is an example of a spiral galaxy, 100,000 light years. Our solar system is about 26,000 light years from the center of the Milky Way. |
Elliptical Galaxies:
Elliptical galaxies are shaped like a sphere. In the sky, they look like an elongated sphere. The elliptical scale classifies galaxies from E0, a perfectly circular galaxy to E7, a very flattened galaxy. These are often very old since no new stars. The stars are very close together, making the galaxy look like one giant star. These galaxies have little cool gas and dust. |
Irregular Galaxies
Galaxies without regular shapes are known as irregular galaxies. They have many bright, young stars and are usually smaller than others. Irregular galaxies are often located near larger galaxies, distorting small irregular galaxy shapes. |