The Wow! signal was an anomylous signal that occured on August 15th 1977, picked up by a radio telescope located at Ohio State University. The telescope was scanning the stars searching for possible extraterrestrial signals as part of the SETI project. The telescope recorded an incredibly strong signal appearing to come from somewhere in the direction of Sagittarius. The signal was so strong that astronomer Jerry Ehman, who first spotted it, circled it in red pen and wrote "Wow!" in the margin. The "Wow! signal," as it would come to be known, became the best evidence ever obtained for extraterrestrial life. The signal only lasted about a minute and was never detected again.
In a 2016 paper, Astronomers Antonio Paris and Evan Davies proposed that the signal could have been caused by a comet orbiting in the inner solar system. The 2016 paper identifies two comets, 266P/Christensen and P/2008 Y2 (Gibbs), as candidates for the wow signal, as they both were suspected to be in the area in August 1977. Both of these comets have large hydrogen clouds surrounding them that could produce the kind of signal detected in 1977. Paris spent about four months in late 2016 and early 2017 with a telescope pointed at comet 266P. He claims that he found strong signals of the same type as the Wow! signal.
A spokesperson from the OSU Radio Observatory, where the Wow! signal was detected, has reached out to express skepticism of this discovery. Specifically, the spokesperson notes that both comet 266P and P/2008 were too far away to have caused the signal, and that there's no prior evidence suggesting that comets can create the type of signal spotted in 1977. In particular, the Wow! signal only lasted for a little over a minute, which would be unusual for a comet.