On Aug. 15, 1977, a 72-second radio signal from space stirred up the Search for Extra-Terrestrial Intelligence (SETI). Astronomer Jerry Ehman viewed the signal on a computer printout and wrote the word “Wow!” on the sheet, giving the signal the moniker it has today. The signal came from the Sagittarius constellation near the center of the galaxy.

Ehman recalled in an interview with Cleveland’s The Plain Dealer: “It was the most significant thing we had seen.” 

The signal, which appeared as the six characters 6EQUJ5, did not have any apparent meaning. It was received by Ohio State University’s Big Ear radio observatory. It caused much excitement, but a similar transmission has not been discovered since, leading many to lose hope that it was an attempt by extraterrestrials to make contact. But it remains a mystery 37 years later, leaving the tantalizing uncertainty—a thread to draw the imagination up into space and onto other worlds inhabited by intelligent life.

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