The Wow! Signal Incident

Added: 2026-05-25

[00:00:00]This story happened in Delaware, Ohio on August 15th, 1977.

[00:00:06]Just after 11:00 p.m., the grounds of Ohio State University's Big Ear radio telescope were quiet. The instrument was part of a long-running sky survey built to scan overhead radio frequencies for natural and artificial signals. Its operation was routine. The telescope did not track objects directly. Instead, the Earth's rotation carried different regions of the sky through its fixed listening area, while computers logged incoming data onto long sheets of paper.

[00:00:37]A few days later, astronomer Jerry Ehman reviewed one of those printouts. In a column of ordinary background readings, one sequence stood out. It read 6 E Q U J 5. In the telescope's coding system, letters and numbers marked signal intensity. This sequence showed a rapid rise and fall over 72 seconds, matching the exact length of time a source would remain inside Big Ear's detection window.

[00:01:04]Ehman circled the sequence and wrote one word beside it on the printout. Wow. The signal was detected near the 1420 MHz hydrogen [music] line, a frequency long considered important in radio astronomy because hydrogen is the most common element in the universe.

[00:01:22]The transmission appeared narrow band, which made it unusual. Natural cosmic sources generally produce broader emissions. According to the observatory record, the source was traced to the direction of the constellation Sagittarius, near the Kai star group.

[00:01:39]Though the telescope's design left two possible positions.

[00:01:43]No confirmed repetition followed. Big Ear returned to the same region repeatedly. Other observatories also searched. Nothing matching the original signal was recorded. The printout remained the central piece of evidence.

[00:01:57]One strong, isolated burst, precisely logged, but never recovered.

[00:02:02]The event was documented, archived, and reanalyzed for decades. Explanations involving terrestrial interference, satellites, reflected transmissions, and astronomical sources were examined in public discussions. But no single cause was confirmed [music] by the original data. What remains is a 72-second signal recorded by an operating [music] radio telescope during a normal survey from a fixed point in the sky that produced no [music] second transmission.

[00:02:31]The notation beside it was informal. The record itself was not.