Are we alone? For a moment on August 15, 1977, it certainly looked like the answer might be no. That night the Big Ear radio observatory at the Ohio State University was blasted by a remarkably intense transmission from the sky. Lasting at least 72 seconds and coming in on an extremely specific frequency, it didn’t appear to have any of the hallmarks of a natural astrophysical phenomenon. Instead it resembled what we’d expect from an artificial source.
The radio signal vanished as quickly as it had appeared, and neither it nor anything quite like it has ever been detected since in the long, unrequited search for extraterrestrial intelligence (SETI). Named the Wow! signal, after an exclamatory note that a SETI researcher scrawled on a printout of the recording, various ideas have arisen that attempt to explain it. Maybe it was strange radiation from a comet. Many researchers argue it was most likely some form of human-made radio interference. Or, just maybe, it was a message from some staggeringly advanced cosmic civilization—a possibility that, even now, has not yet been definitively ruled out—not for scientists’ lack of trying, however.
The latest explanation emerged last week from a trio of astronomers in a preprint that has not yet been subjected to peer review. And sorry, once again, it’s not aliens. The researchers suspect that the Wow! signal was created when a flare from a hypermagnetized, hyperdense star called a magnetar struck a cold interstellar cloud of hydrogen gas. The flare caused the cloud to incandesce in the radio wavelength, and this fast-and-furious outburst was detected by Big Ear.
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