The world-famous Wow! space signal, which was detected by SETI 40 years ago, has finally been explained.
On August 15th 1977, a powerful radio telescope located at Ohio State University detected a strange transmission. The telescope was scanning the stars searching for possible signals from alien civilizations as part of the SETI project, and on that date it found something. The telescope recorded an incredibly strong space signal that appeared to have come from somewhere in the direction of Sagittarius; the signal only lasted about a minute and was never detected again.
The signal was so strong that astronomer Jerry Ehman, who first spotted it, circled it in red pen and wrote “Wow!” in the margin. The “Wow! signal,” as it would come to be known, became the best evidence ever obtained for extraterrestrial life.
At least, until now. One astronomer believes he’s figured out what really caused the Wow! signal and—spoiler alert—it’s not aliens.
Astronomer Antonio Paris has been studying the Wow! signal for a long time. In 2016, he released a paper along with fellow astronomer Evan Davies suggesting that the signal could have been caused by a comet orbiting in the inner solar system. Specifically, the 2016 paper identified two comets, 266P/Christensen and P/2008 Y2 (Gibbs), that were both in the area where the Wow! signal was detected.
Both of these comets have large hydrogen clouds surrounding them that could produce the kind of signal detected in 1977. Paris spent about four months in late 2016 and early 2017 with a telescope pointed at comet 266P, and found strong signals of the same type as the Wow! signal.
Paris also examined several other similar comets and found the same type of hydrogen cloud and the same type of signal, which means that even if comet 266P wasn’t the specific source of the Wow! signal, another comet is most likely the culprit.
This is bad news for anyone holding out hope that the Wow! signal would be aliens, but it’s a solid conclusion to one of the biggest mysteries in astronomy. Now that we know comets can create these otherworldly signals, any future signals we get will have to be vetted much more carefully.
Speaking about the theory before its confirmation, Professor Paris admitted that he had wanted to be wrong. ‘There’s still a bit inside of me that hopes it was aliens,’ he said.
When he first published the theory last year, Professor Paris said the comets produced a cloud of hydrogen gas in their wake which released radiation.