In September of 2002, a mystery emerged from the heart of the Milky Way. Something spat out five flares of powerful radio waves, precisely timed 77 minutes apart. Then, it fell silent. Astronomer Scott Hyman of Sweet Briar College wasn't quite sure what to make of it. He spent years looking for another, without much success, ultimately turning his attention to other work. Twenty years later, while looking for something else, it happened again.