Astronomers using the Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) at the W. M. Keck Observatory have discovered an ultramassive galaxy 12 billion light-years away from Earth. The unusual galaxy, named XMM-2599, formed stars at a very high rate and then died; why it suddenly stopped forming stars is unclear. An artist’s impression of what an ancient star-forming galaxy would look like in visible light. Image credit: NRAO / AUI /...