Cosmic radio waves which have puzzled astronomers for more than a decade, and even led to speculation that they were made by aliens, are probably produced by a huge neutron star, scientists have said.
Telescopes first picked up Fast Radio Bursts in 2001 and they have been recorded hitting Earth in a regular pattern ever since.
They last a few milliseconds but seem to carry as much energy as the Sun releases in a month, suggesting they must come from a huge source of power.
Although pulsars are known to emit bursts of radio waves, they do not do so regularly or with anything like the power of FRBs.
The mystery signals led to speculation among scientists that they could be the first hint of an advanced alien civilisation.
Now scientists have traced the origin of the waves to a dwarf galaxy more than three billion light years from Earth, where a powerful neutron star called a magnetar could have formed.
They found the signal's home by focusing on one recurring burst which had been detected at the Arecibo Observatory in Puerto Rico and managed to pick up the mystery bust nine more times over a six-month period in 2016.