We're living next door to a Cannibal Galaxy whose violent past has been revealed
A study of the small galaxies swallowed by our nearest large galactic neighbor has revealed something of how galaxies grow. In the process, it has hinted at something that, if true, would change the way we see the universe in profound ways. All galaxies, including our own Milky Way, grow by consuming smaller ones. Inevitably, the nearest large galaxy to our own, M31, also known as Andromeda, has eaten many small neighbors. Our first insight into the nature of these events is useful because Andromeda and the Milky Way are on course to meet. That's 4 billion years away, but it's good to be prepared. Dr. Dougal Mackey of the Australian National University and Professor Geraint Lewis from the University of Sydney analyzed streams of stars within Andromeda's halo and identified some as the remnants of galaxies, even gaining approximations of when this occurred. Rather than a steady process, they identified two bursts separated by billions of years. The galaxies in the two r...