
The 'Wow!' signal (credit: The Ohio State University Radio Observatory and the North American AstroPhysical Observatory)
The “Wow!” signal was a radio signal detected by Dr. Jerry Ehman on August 15, 1977 with Ohio State University’s Big Ear radio telescope. This signal, named after Ehman’s reaction, was “so strong that it catapulted the Big Ear’s recording device off the chart,” according to the Big Ear’s website.
The “Wow!” signal has never been detected again. Shuch described it as “one of those things that goes bump in the night and then is gone forever.” The Cape Times explains that the signal “bore all the hallmarks, at the time of its detection, of having a non-Earth origin.”

Dr. Paul Shuch (credit: Paul Shuch)
This, of course, is based purely on the lack of detected radio signals, and assumes that all extraterrestrial civilizations are broadcasting radio signals . . .