Today, a team said they had, for the first time, traced one such flash to a galaxy about six billion light-years from Earth.
Invisible to the human eye, fast radio bursts (FRBs) are radio wave flashes which last a fraction of a second and emit as much energy in a millisecond as the Sun in about 10,000 years.
Scientists still don't know what causes them.
"Our discovery opens the way to working out what makes these bursts," said Simon Johnston of Australia's national science agency, CSIRO, which took part in the project.
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Some have speculated they may be alien signals.
"Nope! Sorry," study lead author Evan Keane of the Square Kilometre Array Organisation said of this theory.
A much likelier source of the FRB observed on April 18, 2015, he said, was the collision of two ultra-dense neutron stars.
The burst was detected by CSIRO's Parke's radio telescope in eastern Australia.
An alert was triggered for other telescopes to follow up, and within hours CSIRO's Compact Array detected an "afterglow" of the flash.
"This involved zooming in by 1,000 times over what we can do with just one telescope," Keane told AFP.
The galaxy identified as the source of the signal is an elliptical one, not spiral like our own Milky Way.
It is about 70,000 light-years wide and has a mass equivalent to about 100 billion Sun-sized stars.
The team said their breakthrough also shed light on another long-standing science question -- that of the "missing matter".
The Universe is thought to be made up of about 70 per cent dark energy, 25 per cent undetectable dark matter, and only about five per cent ordinary matter -- the stuff of which planets, stars and humans are made.
In the latest study, the team could determine the FRB's travel distance and how long it would have taken in a vacuum.