Experts were left puzzled when a missile warning base tracked a UFO.
A UFO was tracked at an RAF base during the 1980s
Officials at RAF Fylingdales in North Yorkshire ordered a secret probe after spotting the "unknown target" back in 1981.
RAF Group Captain David Todd, a senior officer at the base at the time in question, said: "I remember this (incident) particularly clearly. It came as an unknown and radar tracked it.
"It appeared to be in Earth's orbit and we waited for it to come around again but it didn't. People started saying, 'Ooh, is it a UFO?'"
Todd raised the mystery with Serco - the company that designed the radars - and various theories were proposed during the investigation.
He recalled: "They did a hell of a lot of work on it and came up with various theories.
"One was, 'A UFO with little green men inside!'"
It was concluded that the base had "most likely" tracked a meteorite.