Big Ear receives ‘Wow! Signal,’ August 15, 1977

-August 15, 2017

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An Ohio State University radio telescope known as The Big Ear received a radio signal that many believe came in from deep space on August 15, 1977.

The telescope was located at Ohio Wesleyan University's Perkins Observatory, in Delaware, Ohio, and was being operated as a part of a SETI (search for extraterrestrial intelligence) project. It was fixed and used the Earth’s rotation to scan the sky. As such, the Big Ear could observe any given point for just 72 seconds.

The Big Ear radio telescope was being operated as part of a search for extraterrestrial intelligence in 1977. Source: The Ohio State University

The signal was a strong narrowband radio signal detected by university professor Jerry R Ehman. It lasted for the full 72 seconds and could not be detected again.

Ehman was reportedly so amazed at how closely the signal matched the expected signature of an interstellar signal in the antenna used that he circled the signal on the computer printout and wrote the comment "Wow!" on its side. (See image scan of the printout below) The signal then became known as the “Wow! Signal.”

Indeed, the Wow! Signal did closely resemble what researchers expected an extraterrestrial signal would be. Its narrowband matched the telescope's antenna pattern, which indicated that it was at least at a lunar distance and not from a nearer object as such a signal would have a wider pattern.

Its frequency was near the 1420 MHz hydrogen line, where radio transmissions are prohibited.
The signal's strength was 30 standard deviations above the mean background noise, showing that the transmitter used a large amount on energy.

Also, the 72-second-long signal, being studied by the fixed telescope, gradually peaked for the first 36 seconds until the signal reached the center of Big Ear's observation window and then a gradually decreased. As such, both the length of the signal and the bell shape of the intensity graph were considered to correspond with a possible extraterrestrial origin.

Whether the signal was extraterrestrial in nature or not is debatable. Ehman, himself, has stated doubts. But the Wow! Signal did stir much media coverage at its finding and why the signal could not be located again is still pondered today as a great riddle of science.

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Editor's note: This article was originally posted on August 15, 2012 and edited on August 15, 2017.

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