Investigated
What is the Wow! signal and why has no one ever explained where it came from?
Short answer
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The Wow! signal was a powerful, narrowband radio event detected by Ohio State’s Big Ear telescope in 1977; it lasted about 72 seconds and appeared to come from Sagittarius. Its name came from astronomer Jerry Ehman’s handwritten reaction. Because it never recurred, its source remains unidentified: recent research favors a rare natural event involving hydrogen clouds, while an extraterrestrial transmission remains possible but unproven.
The views on this question
Two lenses on the same evidence. Source weight and the primary source ratio show what each rests on.
Alternative
Source weight 50%Lens adapted to this topic: Dissenting explanations and what supports them
Some researchers argue that the signal came from a Solar System object rather than an alien civilization. A cometary-hydrogen-cloud hypothesis reported radio emission near 1420 MHz from comet 266/P Christensen, interpreting this as evidence for a natural origin. However, the available sources do not establish that this comet was present in the correct position in 1977 or that the proposed emission fully matches the Wow! signal, so the explanation remains disputed.
- A 2017 investigation reported 1420.25 MHz radio emission from comet 266/P Christensen and argued that cometary hydrogen could explain the Wow! signal naturally.
- The comet hypothesis challenges the assumption that the signal required an intelligent transmitter.
- The broader natural-origin case is supported by later detections of similar, though much weaker, hydrogen-cloud signals.
- The alternative explanations remain incomplete because no proposed source has been detected producing the same event again.