A mysterious "alien signal" which has baffled scientists since it was discovered in 1977 is now thought to have been cracked.
Ohio State University's Search for Extraterrestrial Intelligence (Seti) project detected the "Wow!" signal almost 50 years ago.
While scanning the sky for proof of intelligent alien life, the research team discovered a 72-second radio burst.
It was thought to be so bizarre that the leading astronomer of the group, Jerry Ehman, wrote "Wow!" on the printout.
The infamous 'Wow!' signal was discovered in 1977
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For years, the unexplained signal has remained one of the strongest hints that alien intelligence may be real.
However, scientists now believe the signal is likely to have had a more rational explanation.
Decades of previously unstudied work from the Seti programme have now been re-analysed by the University of Puerto Rico.
The hypothesis is now that the signal was likely created by radiation from a dead star interacting with hydrogen atoms.
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PICTURED: A general map of the location where the 'Wow!' signal supposedly originated
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The signal was first picked up at Ohio State's observatory
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In space, some atoms of hydrogen produce weak signals which can be picked up by radio telescopes.
However, certain astrophysical processes generate large amounts of energy, like solar flares, which makes the process more visible.
Scientists believe that extra energy in the case of the Wow! signal came from a magnetar, which is a type of collapsed star with an extraordinarily powerful magnetic field.
Professor Abel Mendez of the Planetary Habitability Laboratory at the University of Puerto Rico, who worked on the Arecibo Wow! Project, said: "Our results do not solve the mystery of the Wow! Signal.
"But they give us the clearest picture yet of what it was and where it came from.
PICTURED: Scientists believe the section labelled 'Ds' is where the Wow! signal was created
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"This new precision allows us to target future observations more effectively than ever before."
According to the research team, the breakthrough was only possible because of the large amount of data which had been collected since the 1970s.
Dr Hector Socas Navarro, DIrector of the European Solar Telescope Foundation and one of the co-authors of the study likened the process to "space archaeology".
He said: "We look at old archives with modern science methodologies."
The research is set to be published in the Astrophysical Journal.