A Canadian radio telescope has picked up radio signals thought to be emitted from a galaxy half a billion light-years away.
Known as fast radio bursts (FRB) they were picked up by the CHIME telescope, based near Okanagan Falls in British Columbia.
The radio signals appear to follow a pattern, which repeats every 16.35 days. Over four days, the radio signals would be received twice an hour, before the signal would go silent for another 12 days.
The phenomena first came to the attention of scientists in 2007, puzzling astronomers as to what their source is.
More and more signals like this one are being discovered; until 2016 scientists only knew of one repeating FRB, which was discovered at the Arecibo telescope in Puerto Rico.
Deborah Good, an astronomer at the University of British Columbia in Vancouver, told Scientific American the signal detected was the lowest-frequency FRB discovered so far, appearing at a wavelength of 400 megahertz, breaking the previous record of 700 megahertz.
Where do the signals come from and how significant are they?
Dr. Manisha Caleb, a Postdoctoral Researcher at The University of Manchester's Jodrell Bank Centre for Astrophysics, explained the discovery which is one of only a handful made by astronomers.
She told ITV News: "This particular FRB is relatively close by compared to most others as it originates at a distance of half a billion light-years away. To put it simply, this means that the light left the source even before dinosaurs were roaming the earth."
She explained how astronomers locate such a source, when it's from so far away.
"A special technique called Very Long Baseline Interferometry (VLBI) was implemented to pinpoint the location of these bursts to a galaxy half a billion light-years away.
"Generally, in this technique, several radio telescopes around the world are linked together electronically to form one large virtual radio telescope. The angular resolution of such a telescope is determined by the maximum distance between any two telescopes.
"The FRB was localised by eight radio telescopes of the European Very-long-baseline-interferometry Network (EVN) to milli-arcseconds precision.
"This is equivalent to measuring the width of a human hair at a distance of one kilometre."
She doesn't believe martians are about to stage an invasion on planet Earth, far from it in fact.
"We’ve gone down this road before when pulsars were first discovered, they were dubbed the Little Green Man.
"In astronomy we know of numerous examples of sources that emit periodically.
"Hence, this particular source/system could very well be explained by a binary star system or a precessing, isolated spinning star like those we've already seen in our own galaxy, albeit at much greater distances."