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Yes, mysterious radio signal from space detected in 1977 – but probably caused by comet

A meme circulating on Facebook in South Africa suggests Earth may have been contacted by extraterrestrial intelligence – 42 years ago.

It shows an illustration of large dish antennae with a sky full of stars and galaxies behind them.

“In 1977 we received a Radio Signal that lasted for 72 Seconds. To this day, we still don't know where it came from,” it says.

Is this true? We checked.

The Wow! signal

A 72-second signal was detected in 1977. According to radio astronomer Jerry Ehman, the “source radio emission” entered the receiver of the Big Ear radio telescope at Ohio State University in the US at about 11:16 pm on 15 August 1977.

A few days later, Ehman picked up the unusual signal on a computer printout. It was from a narrow frequency band radio source “of small angular diameter in the sky”, he wrote. 

He highlighted six numbers on the printout in red pen and wrote “Wow!” in the margin opposite them. 

As Ehman and his colleagues analysed the signal, physicist John Kraus, who designed the Big Ear telescope, started calling it the “Wow! signal” or “Wow! source”.

Too little data ‘to draw many conclusions’

In a 30th anniversary report on the signal, written in 2007 and revised in 2010, Ehman said there were several speculations and hypotheses about what could have caused it.

These included planets, asteroids, satellites, planes, spacecraft or even extraterrestrial intelligence. 

Ehman said there was “simply too little data to draw many conclusions” and he chose not to “draw vast conclusions from ‘half-vast’ data”.

New research suggests signal was from comet

In a paper published in the Journal of the Washington Academy of Sciences in 2017, a team at the US Center for Planetary Sciences suggested that the signal might have come from a hydrogen cloud around a comet. “The movement of the comet would explain why the signal was not seen again,” they said.

According to the lead researcher on the paper, astrophysicist Antonio Paris, the comet that they propose caused the signal “was unknown at the time of the signal discovery”. To verify their results, the team took readings from three other comets and found similar results. 

Yes, in 1977 a radio telescope detected a 72-second signal from space. Scientists are now reasonably sure it was caused by a comet. – Taryn Willows


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