The Wow! signal: a 72-second mystery that still haunts SETI
The Wow signal was a strong narrowband radio signal detected on August 15, 1977
On August 15, 1977, Ohio State University's Big Ear radio telescope detected a strong narrowband signal from the constellation Sagittarius. The 72-second burst, later dubbed the Wow! signal, bore the hallmarks of extraterrestrial origin but has never been detected again. Despite numerous hypotheses—from space debris to interstellar scintillation—its source remains unexplained. Recent searches, including a 2022 effort by Breakthrough Listen, have found no trace, leaving the signal one of astronomy's greatest enigmas.
We should have seen it again when we looked for it 50 times. Something suggests it was an Earth-sourced signal that simply got reflected off a piece of space debris.