Ten billion years ago, the Milky Way encountered another galaxy in the vast emptiness of space, and consumed it. Dubbed Gaia-Enceladus by astronomers, this stranger was roughly a quarter the Milky Way’s size, and it forever changed the makeup and shape of our home galaxy.
Scientists have had evidence for a while that the Milky Way saw a major merger in its past. Even without direct evidence here in our home galaxy, scientists know that galaxy collisions are commonplace in the universe. These mergers are the major way that galaxies grow and evolve. But this is the first time that astronomers have been able to pinpoint the ages of different stellar populations within the Milky Way accurately enough to pin down when this merger occurred, and how exactly it affected our home galaxy. Researchers led by Carme Gallart from the Instituto de Astrofísica de Canarias in Spain published their findings ...
