The Wow! Signal

The Wow! Signal's 72-second intensity — about 30 times stronger than background noise — makes it one of the most compelling one-time radio bursts ever recorded, yet it has never repeated. Detected on August 15, 1977, by Ohio State University's Big Ear telescope from the direction of Sagittarius, astronomer Jerry Ehman circled the printout and scribbled "Wow!" The signal matched the hydrogen line at 1420 MHz, an expected extraterrestrial transmission marker, but hundreds of subsequent observations found nothing. A 2017 study proposed a comet as the source, but this was swiftly disputed, and no natural mechanism has been confirmed. The event remains a single fleeting detection: if it were natural, it has never been replicated; if artificial, nothing has been heard since — a silence as profound as the mystery itself.