In 1977, the Big Ear Radio Telescope at Ohio State University picked up a strong narrowband signal from space. The signal was a continuous radio wave that was strong in intensity and frequency and had many expected characteristics of an extraterrestrial transmission. This event would come to be known as the “Wow!” signal, and it remains the strongest candidate for a message sent by an extraterrestrial civilization. Unfortunately, all attempts to pinpoint the source of the signal (or detect it again) have failed.
Click here for original story, There could be four hostile civilizations in the Milky Way, researcher speculates
Source: Phys.org