#20 The Extraterrestrial Signal
In 1977, Jerry Ehman used a radio signal detector to study stars surrounding the Sagittarius constellation. While he was scanning the stars, he picked up a strange frequency that lasted for 72 seconds.
This frequency sounded like it was coming from outer space. He typed “wow” as a response to this frequency that was quite possibly a faint communication with the extraterrestrial.
Several attempts have been made at understanding the story over the years, but no sensible explanation was derived.