In the summer of 1977, he saw six symbols that indicated a 72-second signal 30 times louder than any previous sound from space. He circled the sequence and wrote “Wow!” “The Wow! Signal,” as the noise was called thereafter, had a frequency and shape that suggested intentionality.
However, while the area from which the noise came could be determined, scientists were unable to pinpoint an actual source. In the years since, a number of logical explanations for the signal, like a satellite transmission, military signal or broadcast beam, have been ruled out.
While some still think the sound was extraterrestrials attempting contact, critics are quick to point out that there hasn’t been a repeat transmission since. So either something else made the sound, or aliens are quitters.