The Mystery Behind a 40-Year-Old Signal From Outer Space May Finally Be Solved

"On August 15th 1977, a radio telescope located at Ohio State University detected something strange. The telescope was scanning the stars searching for possible signals from alien civilizations as part of the SETI project, and on that date it found something. The telescope recorded an incredibly strong signal appearing to come from somewhere in the direction of Sagittarius; the signal only lasted about a minute and was never detected again.

"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.
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"Astronomer Antonio Paris has been studying the Wow! signal for a long time. In 2016, he released a paper along with fellow astronomer Evan Davies suggesting that the signal could have been caused by a comet orbiting in the inner solar system. Specifically, the 2016 paper identified two comets, 266P/Christensen and P/2008 Y2 (Gibbs), that were both in the area where the Wow! signal was detected.

"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, and found strong signals of the same type as the Wow! signal."

http://www.esquire.com/news-politics/a55484/wow-signal-mystery-solved/

"In 2016, the Center for Planetary Science proposed a hypothesis arguing a comet and/or its hydrogen cloud were a strong candidate for the source of the “Wow!” Signal. From 27 November 2016 to 24 February 2017, the Center for Planetary Science conducted 200 observations in the radio spectrum to validate the hypothesis. The investigation discovered that comet 266/P Christensen emitted a radio signal at 1420.25 MHz. All radio emissions detected were within 1° (60 arcminutes) of the known celestial coordinates of the comet as it transited the neighborhood of the “Wow!” Signal. During observations of the comet, a series of experiments determined that known celestial sources at 1420 MHz (i.e., pulsars and/or active galactic nuclei) were not within 15° of comet 266/P Christensen. To dismiss the source of the signal as emission from comet 266/P Christensen, the position of the 10-meter radio telescope was moved 1° (60 arcminutes) away from comet 266/P Christensen. During this experiment, the 1420.25 MHz signal disappeared. When the radio telescope was repositioned back to comet 266/P Christensen, a radio signal at 1420.25 MHz reappeared. Furthermore, to determine if comets other than comet 266/P Christensen emit a radio signal at 1420 MHz, we observed three comets that were selected randomly from the JPL Small Bodies database: P/2013 EW90 (Tenagra), P/2016 J1-A (PANSTARRS), and 237P/LINEAR. During observations of these comets, we detected a radio signal at 1420 MHz. The results of this investigation, therefore, conclude that cometary spectra are detectable at 1420 MHz and, more importantly, that the 1977 “Wow!” Signal was a natural phenomenon from a Solar System body."

http://planetary-science.org/research/the-wow-signal/