(CNN) Far outside our Milky Way galaxy, something is causing repeating short bursts of radio waves to be released into space. Scientists have recorded the second repeating fast radio burst to be discovered, according to a study published Wednesday in the journal Nature.

The finding was also presented at the 233rd meeting of the American Astronomical Society in Seattle.

These radio bursts are only millisecond-long radio flashes, and such rapid bursts themselves aren't rare in space.

But this is only the second one that has been found to repeat. The mystery about why these bursts happen and where they come from continues, which always spurs believers to think that advanced extraterrestrial civilizations are creating them.

The first one, deemed FRB 121102 , was discovered in 2015 by the Arecibo radio telescope, and it was revealed in 2018 that the bursts release an enormous amount of energy.

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