The Wow! Signal
The account
A strong, narrow radio signal coming from the direction of Sagittarius would be a message from another civilization.
What investigators found
Picked up by the Big Ear radio telescope for 72 seconds and never repeated. In 2024, a study proposed that hydrogen clouds may have caused a rare natural brightening.
The story
In August 1977, the volunteer astronomer Jerry Ehman was reviewing printouts from the Big Ear radio telescope at Ohio State University, which was searching for signs of intelligent life in space. On one of them, from the night of August 15, he saw the sequence 6EQUJ5, circled it in red pen and wrote next to it: "Wow!"
The signal was strong and lasted 72 seconds, exactly the time it took a point in the sky to cross the telescope's field of view, and it was close to the frequency of hydrogen, the one scientists expected another civilization would use. It came from the direction of the constellation Sagittarius.
It never repeated, despite dozens of searches. In 2024, a team proposed that a hydrogen cloud may have flared in a rare way, a natural explanation not yet confirmed. Big Ear was demolished in 1998 to make way for a golf course.