On August 15, 2017 – 40 years since the Wow! signal was detected on August 15, 1977 by Ohio State University’s Big Ear radio telescope in the United States.
The signal appeared to come from the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin.
Astronomer Jerry R. Ehman discovered the anomaly a few days later, while reviewing the recorded data. He was so impressed by the result that he circled the reading on the computer printout and wrote the comment Wow! on its side, leading to the event’s widely used name.
The entire signal sequence lasted for the full 72-second window during which Big Ear was able to observe it, but has not been detected since, despite several subsequent attempts by Ehman and others. Many hypotheses on the origin of the emission have been advanced, including natural and man-made sources, although none of them adequately explains the result. The Wow! signal remains therefore the strongest candidate for an alien radio transmission ever detected.
In 2017, Antonio Paris proposed that the hydrogen cloud surrounding two comets, 266P/Christensen and 335P/Gibbs, now known to have been in roughly the right position, could have been the source of the Wow! signal. However, this theory has attracted strong criticism, including from members of the original Big Ear research team, as a more detailed analysis shows the cited comets were not in the beam at the correct time. Furthermore, comets are not radio-bright at these frequencies, and there is no explanation for why a comet would be observed in one beam but not in the other. (From Wikipedia, the free encyclopedia)