Galaxies

Image Courtesy of NASA

Galaxies are a group of stars, dust, gas, and planets held together by gravity. The image to the right depicts many different galaxies. You may have noticed  that not all galaxies have the same shape. You will find that galaxies are classified according to their shapes.

Galaxies, like the Milky Way Galaxy, have a spiral shape. The most common shape for a galaxy is like a football, or elliptical. Other galaxies have very irregular shapes or no defined shapes. No matter what the shape, each galaxy has its own special properties and characteristics. In this topic, you will investigate the three major types of galaxies and learn the properties of each type.

Essential Questions

• What are the different types of galaxies?
• How do galaxies change over time?