The Wow! Signal
In 1977 a radio telescope in Ohio caught one of the strongest signals ever detected from deep space. It has never been heard again.
The story
On 15 August 1977, Ohio State University's "Big Ear" radio telescope was scanning the sky as part of a search for extraterrestrial intelligence.
Days later, astronomer Jerry Ehman was reviewing the computer printouts when he saw a sequence of characters, 6EQUJ5, that showed a sudden, intense spike. He circled it and wrote one word in the margin: "Wow!"
The signal lasted about 72 seconds, which is exactly how long Big Ear's fixed beam took to sweep across one point in the sky as the Earth turned. That is what a signal from a distant, fixed source would look like.
It came from the direction of the constellation Sagittarius, at a frequency close to 1420 MHz, the natural radio frequency of hydrogen, which scientists had long suggested an alien civilisation might use.
The evidence chain
- The original printout with Ehman's handwritten "Wow!" survives and is documented by the Big Ear observatory.
- Repeated searches of the same patch of sky, by Big Ear and later by other telescopes, have never detected the signal again.
- Because it never repeated, it cannot be studied or confirmed, and a one-time signal is not evidence of aliens.
- In 2024 a team of astronomers proposed a natural explanation: a cold hydrogen cloud suddenly brightened by a powerful burst of radiation. This is a hypothesis, not a confirmed answer.
Verdict
UNEXPLAINEDThe event is real and documented; its cause is unknown.
The signal itself is real and well documented. Its source is unknown. There is no evidence that it came from aliens, and no natural explanation has been confirmed either.
Sources
Published 2026-10-24. Spotted an error? Email provenmysteries@gmail.com.