On 15 August 1977 the Ohio State Radio Observatory was doing what it did every day, scanning overhead skies for signals as part of a search that would run 22 years. Nobody noticed anything that night. The record of what happened is a line of characters on a printout.
Six characters: 6EQUJ5. The volunteer astronomer Jerry Ehman found them the next morning and wrote WOW! beside them in red ink. The letters encode channel energies on a 31-step scale, where U is a signal 30 times as strong as a 1, and the whole event lasted just over a minute.
Late on Monday 15 August 1977, the Ohio State Radio Telescope, a metal assemblage spread across three acres of farmland, was deep into its daily routine of observing overhead skies for narrow-band signals. A strong signal arrived, and nobody noticed until the following morning.
Jerry Ehman, an astronomer volunteer, was reading the previous day’s line-printer output. Each line showed the radio energy in 50 , averaged over 10 seconds, with each value binned into one of 31 steps from 0 to 9 and then A to U.
What he found lasted just over a minute and was conspicuous enough that he wrote WOW! beside it in red ink. The characters 6EQUJ5 carry no meaning beyond those encoded energies, and a U stands for a signal 30 times as strong as a 1.
The shape of the rise and fall is what keeps it interesting. It behaved as a fixed on the sky would while the Earth turned, which told Dixon it was at least as far away as the moon. The direction was silent when they looked again immediately afterwards, and he expects it to remain a .
wat. Six characters, just over a minute, and nothing since.
wat wat
It is the best-known single-event candidate in the history of the search, and it has never been seen again.
How do we know?
The SETI Institute sets out the detection, the printout format, and the judgement of Robert Dixon, who directed the observatory at the time.
What is still unknown
One detection with no repeat, which is exactly what makes it impossible to settle.
Learn something?
Where to next
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