A 72-second radio signal from 1977 has never been explained or heard again
An Ohio radio telescope recorded a strong, narrow signal from the direction of Sagittarius. Decades of listening at the same spot have turned up nothing since.
- Institutions
- Ohio State University, SETI Institute
- Reported
- 1977
- Status
- A possible finding that has not been established.
No imagery is attached yet. Agency imagery is free to use with a credit line, so anything added here will carry one.
What they found
On 15 August 1977 the Big Ear radio telescope at Ohio State recorded a burst of radio energy far stronger than the background, lasting the full 72 seconds the telescope's fixed beam would have kept any fixed point in view. The astronomer reviewing the printout circled it and wrote Wow! in the margin, which is how it got its name. It came from the direction of the constellation Sagittarius.
How they found it
Big Ear did not steer. It stared at a strip of sky and let the Earth's rotation carry sources through its beam, so a genuine object beyond Earth should rise and fade over about 72 seconds. The signal did exactly that, which is the main reason it was taken seriously: it behaved like something in the sky rather than something on the ground. It was also narrow in frequency, sitting close to the natural emission frequency of hydrogen, a band long argued to be a sensible place to listen.
Why it matters
The Wow! signal is the single most cited candidate in the history of the search for radio technosignatures, and it is a useful benchmark for how the field handles a result it cannot repeat. A signal that cannot be observed again cannot be checked, and the discipline's answer has been to keep the case open rather than either dismiss it or claim it.
What this does not mean
This is not evidence of an extraterrestrial transmission. It was never detected again despite repeated searches with more sensitive instruments, and a result that cannot be reproduced cannot be confirmed. Explanations put forward over the years include a passing comet, since ruled unlikely by most researchers, and more recently a proposal that clouds of cold hydrogen briefly brightened by a burst from a magnetar could produce a similar signature. None of these has been established. Earthly interference has never been fully excluded either.