What is a galaxy merger?
Quick Answer
A galaxy merger is when two or more galaxies collide and combine under gravity. These events can trigger bursts of star formation and reshape the galaxies involved.
The Full Story
Galaxy mergers are common over cosmic time because gravity pulls nearby galaxies together. When galaxies interact, their stars usually do not collide directly because space between stars is so large, but gas clouds can collide and compress, forming new stars. Mergers can also feed central black holes and transform galaxy shapes. The Milky Way is expected to merge with Andromeda in about 4 to 5 billion years. Many elliptical galaxies likely formed through past mergers.
Key Facts
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Suggested video title for this topic:
"When galaxies crash, the stars mostly miss—but the consequences are huge"
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