Aug. 15, 1977: The Wow! Signal arrives

Today in the history of astronomy, E.T. is calling. (Maybe.) | Published: August 15, 2026 Jerry Ehman’s note in the margins of a data printout gave the Wow! Signal its name. Credit: Big Ear Radio Observatory and North American AstroPhysical Observatory (NAAPO)/Public domain via Wikimedia Commons On Aug. 15, 1977, a narrowband radio signal was detected by the Big Ear Radio Telescope at Ohio State. The signal was powerful, lasted for 72 seconds, and was picked up on only 1 of 50 possible channels. It also showed a distinct pattern – starting low, growing, and then decreasing again – suggesting it was passing over and therefore had a celestial, not earthly, origin. A few days after the signal was received, astronomer Jerry Ehman spotted it in a computer print-out of data and jotted “Wow!” in red ink next to it. So what was the Wow! Signal? Astronomers still aren’t sure. The SETI Institute conducted follow-up investigations, but the phenomenon has never repeated; despite some characteristics that might suggest it was a signal from extraterrestrial life, that lack of repetition is an argument against E.T. More likely, it was a natural astronomical event that we lacked the necessary tools to analyze in 1977. Theories continue to be evaluated, including a recent paper proposing that it was the result of a flare from a magnetar interacting with a cold hydrogen cloud. No one could have guessed that in 1977, of course – magnetars weren’t even suggested until 1992. Elisa Neckar is senior production editor of Astronomy magazine, and the editor of the Today in the History of Astronomy feature on Astronomy.com.