Late on the night of August 15, 1977, a radio telescope shaped like three football fields sat in a field outside Delaware, Ohio, quietly listening to the sky. It heard something. For exactly 72 seconds, a signal rose out of the static, peaked, and faded away again, and nobody noticed for days.
A Man at His Kitchen Table
Jerry Ehman was a volunteer, not paid staff, when he sat down to review a stack of computer printouts from Ohio State’s Big Ear telescope. It was tedious, repetitive work, columns of characters representing radio noise, most of it meaningless background hiss he’d scanned through a thousand times before. Then he found a run of characters that didn’t look like anything he’d seen: 6EQUJ5. In the system Big Ear used, letters meant a stronger reading than any single number could hold, and “U” meant the signal had spiked to more than 30 times the normal background noise. Ehman circled it in red ballpoint pen and, without really thinking about it, wrote a single word in the margin. Wow!
The signal had come from the direction of Sagittarius, at almost exactly 1420 megahertz, the specific frequency that hydrogen, the most common element in the universe, naturally emits. Physicists had speculated back in 1959 that any civilization trying to signal across the galaxy might choose that exact frequency, reasoning that any species advanced enough to build a radio telescope would already know it well. Whatever produced the signal Ehman was looking at, it had shown up precisely where theory said an alien transmission should.
Something Nobody Could Explain Then, or Now
Here’s what made it so hard to dismiss. The signal rose and fell in exactly the pattern you’d expect from a real point in the sky, gradually building for 36 seconds as Earth’s rotation carried the telescope’s fixed beam across it, then fading as it moved away, the signature of something genuinely out there, not equipment noise or a glitch. Ehman and his colleagues pointed Big Ear back at that same patch of sky more than 50 times over the following weeks and months. Nothing. Other observatories tried too, in 1987, 1989, 1995, 1999, with instruments considerably more sensitive than Big Ear ever was. Still nothing.
Ehman himself stayed genuinely torn about it for the rest of his life. In 1994 he leaned skeptical, telling a reporter that something suggested an earthbound signal reflecting off orbital debris. By 2019, in an interview, he’d shifted, saying he was convinced the Wow! signal genuinely had the potential to be humanity’s first signal from extraterrestrial intelligence. He never landed anywhere permanently. “I honestly can’t” claim it was aliens, he told the Cleveland Plain Dealer in 1994, before adding with a laugh that he wished he could.
A Detail Nobody Plans For
There’s a strange footnote buried in the history here, the kind you can’t invent. According to an essay NPR aired for SETI’s 50th anniversary, the Wow! signal arrived just hours before Elvis Presley died on August 16, 1977. Two completely unrelated moments, one reaching Earth from somewhere near the galactic center, the other happening in a bathroom in Memphis, landing within the same handful of hours almost by accident. Neither one had anything to do with the other. History just happened to file them side by side.
The Search Continues, Long After Ehman Stopped Looking
Big Ear itself is gone now, dismantled in 1998; the land it stood on became part of a golf course. But the signal kept generating new research decades after the original telescope fell silent. In 2020, astronomer Alberto Caballero identified a sun-like star roughly 1,800 light-years away sitting within the signal’s possible coordinates, offering, for the first time, an actual candidate source to point future searches at. Then in 2024, a team working with archived data from the Arecibo Observatory in Puerto Rico proposed a different answer entirely, that stellar radiation striking a cold cloud of hydrogen gas could produce a brief, natural flare-up resembling exactly what Big Ear recorded. If you’re curious about the broader question the Wow! signal keeps circling back to, whether anyone else is out there listening at all, our piece on the Fermi Paradox picks up exactly where this mystery leaves off.
Jerry Ehman died in 2025, at 88 years old, having spent nearly five decades telling journalists, patiently and honestly, that he simply didn’t know. The original printout still exists today, held in the Ohio History Connection’s archives, the red ink slightly faded, “Wow!” still perfectly legible. Whatever produced that signal, if it was ever aimed at anyone at all, has no idea it was ever received.
For more on the ongoing research, check out the Ohio History Connection’s archived printout and the detailed technical account from the Ohio State University Radio Observatory.