Galaxy Collisions

Galaxies can crash into each other in space. These galaxy collisions happen very slowly. They take hundreds of millions of years to finish. When galaxies crash, their stars and gas get mixed together. The two galaxies often turn into one big new galaxy.

How Collisions Happen

Gravity pulls galaxies toward each other. When they get close, they start to change shape. Long streams of stars stretch out like ribbons. The gas clouds inside the galaxies smash together. This makes lots of new stars form.

Stars Do Not Hit

You might think stars would crash during a galaxy collision. But stars are so far apart that they almost never touch. Space inside a galaxy is mostly empty. The gas and dust do crash together, but the stars just pass by each other. Our Milky Way will one day crash into the Andromeda Galaxy.

Fun Facts

• The Antennae Galaxies are two galaxies now in the middle of a collision.
• Galaxy collisions often make a burst of new stars.
• Our galaxy has already eaten smaller galaxies in the past.

Did You Know?

The Milky Way and Andromeda will begin to collide in about 4.5 billion years, but life on Earth will not notice it happening.