Back on August 15, 1977, a signal, thought to be of extraterrestrial origin, was detected at The Big Ear radio telescope at Ohio State University by Dr. Jerry Ehman, working in conjunction with SETI. He was so excited by the signal that on a computer printout of the data, he circled the short segment and wrote, "Wow!" next to it (seen here).
Although the configuration of the equipment and a delay between the reception of the signal and the discovery on the computer printout made finding the precise location difficult, it was determined that the source was in Sagittarius (seen here). More precisely, about 2.5 degrees south of the fifth-magnitude star, Chi Sagittarii. The signal lasted for 72 seconds, and was not repeated.
Naturally, as equipment improved and capabilities improved they searched for the signal again. In 1987 and in 1989, Robert Gray, searched, but didn’t find anything. Gray, using the Very Large Array (which I sometimes call the Whopping Huge Array and is seen here), tried again in 1995 and 1996, with no results. And in 1999, Gray, with Dr. Simon Ellingsen, used the University of Tasmania’s Hobart 26m radio telescope in six 14-hour observations and detected nothing.
On the 30th anniversary of finding the signal, Ehman updated the findings and his opinions on the Wow! signal. He wrote:
Thus, since all of the possibilities of a terrestrial origin have been either ruled out or seem improbable, and since the possibility of an extraterrestrial origin has not been able to be ruled out, I must conclude that an ETI (ExtraTerrestrial Intelligence) might have sent the signal that we received as the Wow! source. The fact that we saw the signal in only one beam could be due to an ETI sending a beacon signal in our direction and then sending it in another direction that we couldn't detect. Of course, being a scientist, I await the reception of additional signals like the Wow! source that are able to be received and analyzed by many observatories. Thus, I must state that the origin of the Wow! signal is still an open question for me. There is simply too little
data to draw many conclusions. In other words, as I stated above, I choose not to "draw vast conclusions from 'half-vast' data".
But even if the source was an extraterrestrial intelligence, which by itself would be an astounding discovery, that does not translate into a capability to travel interstellar distances. We have been radiating radio signals for more than 100 years, which means, of course, that none of our signals could have reached any of the stars in the small cluster around Chi Sagittarii. That means they wouldn’t be looking for us and wouldn’t know about us. And even if they had discovered our radio signals, we cannot reach them and that might mean they can’t reach us... Yet.