The Wow! Signal mystery revolves around an inexplicable radio signal received on August 15, 1977, by Ohio State University's Big Ear radio telescope. Astronomer Jerry R. Ehman discovered an intense and unusual 72-second signal, represented by the notation "6EQUJ5" on the data printout. The signal's strength and characteristics were unlike typical natural radio sources, leading Ehman to circle the signal and write "Wow!" in the margin, giving it its name. Despite numerous attempts to detect a similar signal and identify its origin, the Wow! Signal remains a cosmic enigma.
The mystery has fueled speculation about potential extraterrestrial origins, though no conclusive explanation has been found, making it one of the most famous and enduring puzzles in the search for extraterrestrial intelligence.