Even though we won’t be around when M31 approaches, what will be the earliest effects of the collision on Earth, the Sun, and the solar system’s planets?

Also known as M31, the Andromeda Galaxy can be viewed with the naked eye.

John Gleason

The earliest effect of the collision between the Milky Way and the Andromeda galaxies would be a change in the night sky. Compared with today’s view, where the Milky Way disk appears as a strip of stars stretching across the night sky, Milkomeda’s stars will be scattered all over the sky. The chance that a star would pass sufficiently close to disturb planetary orbits is extremely small.