72 Seconds from Sagittarius: The Signal That Made an Astronomer Write "Wow!"

2026-07-16 · Signals & Sounds · 8 min read

On the night of 15 August 1977, no human being was listening to the sky over Delaware, Ohio. The instrument that watched it was a radio telescope so large that locals struggled to describe it: a flat aluminium listening surface roughly the size of three football fields, built years earlier by the astronomer John Kraus and known to everyone as Big Ear. It could not turn to follow a star. It simply lay tilted toward the heavens while the rotation of the Earth dragged its fixed field of view across the cosmos, minute by minute, night after night. Whatever drifted overhead was not heard by anyone at the time. It was printed. A computer translated the incoming radio energy into columns of numbers and letters and spat them onto fan folded paper, where they waited, silent and unread, for a volunteer to find the time to check them.

Some days later a volunteer named Jerry Ehman sat down with a fresh batch of those printouts. Ehman worked without pay for the Ohio State University SETI program, at the time the longest running search for extraterrestrial intelligence anywhere on Earth, and the work was mostly tedium: endless low numbers, the faint and even hiss of a quiet universe. Then his eye caught a vertical run of characters that did not belong there. 6EQUJ5. He knew at once what those symbols meant, and he reached for a red pen, circled the sequence, and wrote a single word in the margin. Wow! The name stuck. Nearly fifty years later, that is still what the signal is called.

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