This Massive Galaxy was Done Forming Stars at Just 1.5 Billion Years Old

Astronomers have discovered a distant, massive galaxy, seen as it was at about 1.5 billion years after the Big Bang. And it seems to be done forming stars. It's the earliest known example of a massive galaxy that has finished forming stars. And it implies that other massive galaxies may have completed the first phase of their growth this early in the universe’s history as well.