Was the “Wow!” Signal From Aliens or a Comet Flyby?

The 1977 blast from space is often cited as our best evidence of alien contact, but a news study suggests it may have just been comets

Wow! signal
The data readout of the "Wow! signal" The Ohio State University Radio Observatory and the North American AstroPhysical Observatory (NAAPO)-Public Domain via Wikimedia Commons

A powerful signal from space, detected decades ago and thought to be a potential alien transmission, might have been a pair of passing comets, reports Jesse Emspak for New Scientist

In the middle of August 1977, Jerry Ehman, a volunteer researcher at Ohio State University’s Big Ear radio observatory, was sorting through the data from a few days before—columns of numbers and letters crawling across perforated paper. As he scanned through the mind-numbing pages, one sequence popped out at him, writes Patrick J. Kiger for National Geographic.

The sequence was a series of letters and numbers denoting an abnormally large and long blare, like a trumpeting horn compared to the background hum of the universe. In excitement, Ehman circled the sequence in red pen and wrote “Wow!” in the margin. 

The observatory was searching for alien life, scanning the skies for a frequency close to 1420 megahertz. This frequency has long been considered the go-to for alien transmissions. It is the frequency that the extremely common element hydrogen both absorbs and emits energy, explains Emspak.

Beaming to Earth from the direction of the constellation Sagittarius, the signal was strong. It trumpeted more than 30 times greater than the background hum of the universe, and lasted about 72 seconds (the amount of time the telescope could focus on a single point), Kiger writes. 

The strength of the broadcast and the fact that at that frequency it was able to penetrate the atmosphere led researchers to believe it might be intentional. They dubbed it the “Wow! signal.”

Yet over the years, no one has heard it again. National Geographic Channel actually staged a reply in 2012 on their special "Chasing UFOs," Mark Memmott reports for NPR. But the mystery and excitement remains, and until now, scientists never had a good explanation for what the signal could be save for an alien transmission.

Antonio Paris, an astronomer and professor at St. Petersburg College in Florida, thinks the beacon might have been the passing roar of two comets called 266P/Christensen and P/2008/ Y2 (Gibbs), and recently published this idea in the Journal of the Washington Academy of Sciences.

As comets circle closer to the Sun, the energy from our star heats their frozen surface up enough to create the plume of gas that streams behind them. Much of that tail is made up of water and thus a lot of hydrogen. If both comets, which were only discovered in the past decade, passed in front of Big Ear’s field of view in 1977, this could explain the powerful and irreproducable event.

“I came across the idea when I was in my car driving and wondered if a planetary body, moving fast enough could be the source [of the “Wow! signal],” Paris tells New Scientist. But the only way to know for sure is to monitor the signal produced by comets in the same region of the sky where researchers detected the "Wow!" signal. 

Research James Bauer, of the Jet Propulsion Laboratory in California, is skeptical about the suggestion, according to Emspak. If comets were blasting out signals near the wavelength of hydrogen emissions, we would have seen it before, he says.

The only way to know for sure is to take more observations, but it may be a few more years before such an event occurrs. One comet is predicted to pass through the right area in late January, 2017 and another in early January 2018.

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