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

2026-06-27 · Signals & Sounds · 9 min read

On a warm night in the middle of August 1977, no human being was listening to the sky over Delaware, Ohio. The instrument that watched it - a radio telescope so large that locals struggled to describe it, a flat aluminum listening surface roughly the size of three football fields, built years earlier by the astronomer John Kraus - could not even turn to follow a star. It simply lay tilted toward the heavens while the rotation of the Earth itself dragged its fixed field of view across the cosmos, minute by minute, night after night. Whatever drifted overhead was not heard. 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. If a signal ever came from another world, this is how it would arrive: not as a voice in a headset, but as ink on a page that nobody had opened yet.

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 snagged on 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 astonished word in the margin. Wow! The name stuck. Nearly fifty years later, we are still calling it that.

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