Arecibo Observatory spots a fast radio burst that keeps on bursting

From nowhere, they appear as a sudden surge of power in the radio spectrum. Then, a few milliseconds later, they're gone—and as far as we could tell, they never come back. They've picked up the name "fast radio bursts," but nobody's entirely sure of what produces them. Follow-up observations have generally failed to find anything interesting in their direction, and the bursts didn't seem to repeat, leaving everyone who cares about these sorts of things a bit mystified.

One possible explanation for their one-time-only appearance would be that they're the product of a process that destroys the object that creates them. Thus, if they were produced by the collapse of a neutron star into a black hole (to give just one example), there'd be no way for that to happen twice.

But a new study suggests that at least one of them has repeated, which would take cataclysmic explanations off the table. There are enough differences between this burst and previously observed ones, however, to raise the question of whether there might be several processes producing similar surges in radio emissions.