Southern Television broadcast interruption

The Southern Television broadcast interruption was a broadcast signal intrusion, or pirate broadcast, that occurred on 26 November 1977 in parts of southern England in the United Kingdom. The audio of a Southern Television broadcast was replaced by a voice claiming to represent the "Ashtar Galactic Command", delivering a message instructing humanity to abandon its weapons and live in peace with one another so it could participate in a "future awakening" and "achieve a higher state of evolution".

Source: Wikipedia — Southern Television broadcast interruption (CC BY-SA 4.0)