Which galaxy is expected to collide and merge with the Milky Way in about 4.5 billion years?

The Andromeda Galaxy is expected to collide and merge with the Milky Way in about 4.5 billion years.

Andromeda, also called M31, is the nearest large spiral galaxy to the Milky Way. It lies roughly 2.5 million light-years away and is moving toward our galaxy because of their mutual gravity. Current models predict a prolonged interaction rather than a single, instantaneous crash.

Although the galaxies contain hundreds of billions of stars, direct star-to-star collisions are very unlikely because the distances between stars are enormous. Their gas clouds, dust, stellar orbits, and central black holes will be strongly rearranged. The eventual merged galaxy is sometimes informally called Milkomeda.

The exact timetable is not perfectly certain because it depends on Andromeda’s sideways motion and the gravitational influence of nearby galaxies. The Triangulum Galaxy may also participate in the future interaction. The Sun itself could end up in a different orbit within the merged system, while Earth’s local fate will depend mainly on the Sun’s own evolution.