Astronomers over the years have picked up dozens of "fast radio bursts" (FRBs) — mysterious radio signals detected from an unknown part of the cosmos. But for only the second time, they have now found one that repeats itself, making it more likely that we might find out where they come from.

The repeating FRB was picked up by a group of Canadian astronomers, according to a study published Wednesday in the journal Nature. It was one of 13 new FRBs the team detected during three weeks in the summer of 2018.

Astronomers have been finding FRB's since 2002, though dozens of discoveries have shed little light on what these signals are or where they originate. The signals travel billions of light-years through the cosmos but only last a fraction of a second, making them difficult to study. Many theories have been thrown out to explain them — one Harvard University professor even suggested they might be signs of alien life.

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Until now, only one FRB — which was labeled FRB 112102 — was found to repeat itself later on. The Canadian astronomers say they've found a second repeating signal that is distinct from the first one. The new signal is known as FRB 180814.J0422+73.

"They're in a completely different part of the sky and at least a billion parsec away from each other," Shriharsh Tendulkar, a post-doctoral fellow at McGill University who is on the team, told CNET. "We don't know the precise distance to the second one yet." (A parsec is a measure of distance equal to about 3.26 light years.)

While FRB 112102 repeated itself once, this new signal repeated itself six times, the study says. It was also more twice as close to Earth as the previous repeater, popping up about 1.5 billion light-years away.

The discovery is a sign that there could be even more repeating FRBs out there waiting to be found — and maybe even an answer to the mystery of their source.

"With more repeaters and more sources available for study, we may be able to understand these cosmic puzzles — where they're from and what causes them," Ingrid Stairs, a University of British Columbia professor who collaborated on the study, said in a statement.