The "Wow! Signal" is a strong narrowband radio signal detected on August 15, 1977, by astronomer Jerry R. Ehman while working on a SETI project at the Big Ear radio telescope in Ohio. The signal lasted for 72 seconds and appeared to come from the direction of the constellation Sagittarius, specifically near the star Tau Sagittarii. This signal was unusual because it matched the expected characteristics of an extraterrestrial transmission, leading to excitement in the scientific community. Despite numerous attempts to detect it again, the "Wow! Signal" has never been observed again, leaving its origin a mystery.