A study of the motions of different stellar populations in the Andromeda’s disk has revealed a violent history of mergers with dwarf galaxies in the galaxy’s recent past. Hot stars burn brightly in this image from NASA’s Galaxy Evolution Explorer, showing the UV side of a familiar face. At 2.5 million light-years away, the Andromeda galaxy is our Milky Way’s largest galactic neighbor. The galaxy spans 260,000 light-years across....
