The Andromeda–Milky Way collision is a galactic collision predicted to occur in about 4 billion years between the two largest galaxies in the Local Group—the Milky Way (which contains the Solar System and Earth) and the Andromeda Galaxy.[1][2][3][4] The stars involved are sufficiently far apart that it is improbable that any of them will individually collide.[5] Some stars will be ejected from the resulting galaxy, nicknamed Milkomeda or Milkdromeda.

Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity.[3] Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance.[3] They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision.[9][10] Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.[9][10]

Excluding planetary engineering, by the time the two galaxies collide the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life; that is currently estimated to occur in about 3.75 billion years due to gradually increasing luminosity of the Sun (it will have risen by 35–40% above the current luminosity).[11][12]

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https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision