Astronomers watched 35 explosive outbursts from a rare repeating “fast radio burst” (FRB) as it shifted in frequency like a “cosmic slide whistle,” blinking in a puzzling pattern never seen before.

FRBs are millisecond-long flashes of light from beyond the Milky Way that are capable of producing as much energy in a few seconds as the sun does in a year. FRBs are believed to come from powerful objects like neutron stars with intense magnetic fields  —  also called magnetars  —  or from cataclysmic events like stellar collisions or the collapse of neutron stars to form black holes. Complicating the FRB picture, a few FRBs are “repeaters” that flash from the same spot in the sky more than once, while the majority burst once and then vanish.