At 5:12 p.m. on November 26, 1977, an unidentified voice appeared on the transmitters of Southern Television in the United Kingdom. Identifying itself as Vrillon, representative of the Ashtar Galactic Command, the voice broke in to a news broadcast to warn viewers of “the destiny of your race,” “so that you may communicate to your fellow beings the course you must take to avoid a disaster which threatens your world and the beings on other worlds around you.”

Accompanied by a deep buzzing, the voice warned against the use of nuclear weapons and stated that humanity had “but a short time to learn to live together in peace and goodwill” before it destroyed itself.

Investigators decided that pranksters were behind the broadcast, aiming a transmitter at a VHF receiver to overpower the “official” signal with a joke message.

But no one knows for sure.