Milky Way + Andromedia = Milkomeda
Astronomers have calculated that, in five billion years, the Milky Way and our closest neighbouring galaxy, Andromeda, will violently collide, creating a new merged galaxy, which has been dubbed Milkomeda. The two galaxies will (apparently) swing past each other in less than 2 billion years, then again 1.5 billion years after that, before merging 5 million years from now. Scientists have calculated that there is a 3% chance that the sun will defect to Andromeda during the second close pass, in which case viewers on Earth (assuming there’s any left by that point) would see the Milky Way as a spiral in the night sky.
If you’d like to see what the “merger” might look like, watch this video. I find it oddly beautiful, given how cataclysmically destructive the whole thing is. It’s funny to think that each of the two spirals of white contains hundreds of billions of stars.