Galaxies

A galaxy is a giant group of stars floating in space. It also has gas, dust, and planets. Gravity holds it all together. Our Sun lives in a galaxy called the Milky Way. There are billions of galaxies in the universe. Each one can have billions of stars inside it.

Shapes of Galaxies

Galaxies come in many shapes. Some look like flat spinning disks with long arms. These are called spiral galaxies. Others look like round or oval balls. These are called elliptical galaxies. A few galaxies have no set shape at all. Those are called irregular galaxies.

A Hubble telescope picture showing faraway galaxies glowing in deep space.
A Hubble telescope picture showing faraway galaxies glowing in deep space. (ESA/Hubble & NASA Acknowledgement: Judy Schmidt (Geckzilla) / Wikimedia Commons)

How Big Are They?

Galaxies are so big that it is hard to picture them. Light from one side can take many thousands of years to reach the other side. Our Milky Way has about 100 billion stars. Some galaxies have even more. Galaxies often group together in clusters.

Fun Facts

  • The closest big galaxy to us is called Andromeda.
  • Most galaxies have a giant black hole in the middle.
  • New stars are born inside clouds of gas in galaxies.

Did You Know?

Scientists think there may be more than two trillion galaxies in the whole universe!