It appears that an explanation for the “Wow!” signal might have been found. According to a recent experiment by a team of researchers with the Center for Planetary Science, which is pending peer review, it may have been a passing comet. You can see last year’s proposal for the recent experiment HERE, and the 16-page report of the results HERE. The comet suspected of causing the signal was unknown in 1977 when the “Wow!” signal was received.
As a reminder, the “Wow!” signal was an exciting discovery for fans of SETI. At the time (1977), SETI had the Ohio state University Big Ear radio telescope searching for a signal within the frequency of hydrogen, 1420 megahertz, on the theory that it would be used by a civilization intending to be heard. Nothing out of the ordinary was detected until August 15, 1977. The signal received was a massive burst of exactly the haystack-needle signal being sought.
Of course, the problem with the “Wow!” signal, in SETI circles, has always been that it never repeated, so it was probably not an alien signal. However, all known other sources for the signal were ruled out at the time. It was not of Earth origin, and there is nothing in that part of the sky to account for the signal. So the new experiment offers a plausible explanation for the event.
But SETI enthusiasts should not be discouraged. The “Wow!” signal was detected with limited technology by today’s standards, it neither proved nor disproved anything, and it has always been viewed with appropriate skepticism by SETI scientists. For instance, this 2015 Astrowatch.net interview, published on Phys.org, about SETI, the signal was discussed as dubious evidence of extraterrestrial civilization. The interview participants were key figures in the search for extraterrestrial intelligence (SETI’s Seth Shostak, Paul Shuch, Douglas Vakoch and Gerry Harp). Although the “Wow!” signal is relatively famous, the interviewees make clear that the signal never met a critical indicator of intelligent origin—it did not repeat. Without that, according to Vakoch, “we have no basis for thinking it was really from an extraterrestrial civilization.” Moreover, the signal is not particularly extraordinary by today’s standards. SETI now uses the Allen Telescope Array. Compared to current surveys, the “Wow!” signal “isn’t at all special or different from signals that we observe every day at the ATA,” Harp said.
It is also worth noting that with present technology immediate follow-up is possible with any interesting signal. With improved detection capabilities and every-increasing computer power, the search grows stronger every year, and the likelihood increases that something extraordinary will be found.