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 radio signal appearing to originate from the constellation Sagittarius, which astronomer Jerry Ehman labeled "Wow!" after discovering it while analyzing data. Despite numerous follow-up searches and scientific investigation, the signal has never recurred and remains unexplained, though its single occurrence and lack of replication limit conclusions about its extraterrestrial origin.