The truth is out there so said Mulder and Scully with the 'there' in this case being the desert in Roswell in 1947.
Probably the most debated extra-terrestrial event happened in 1947 when either a UFO or a weather balloon crash-landed on a farm near Roswell Air Base, New Mexico.
A rather large group of people believe that the 'weather balloon' was actually an Unidentified Flying Object from outer space and the military recovered three or four alien bodies.
For many that is where the story ends but there is a conspiracy theory that takes it up a notch and that one of the aliens was still alive and he was cared back to health until his fellow aliens could come to pick it up.
In return, the grateful alien established an exchange program with the JFK and then Johnson run Governments that made arrangements for two spaceships to not only pick it up, but take along a dozen specially trained astronauts in 1965.
The astronauts were taken to the aliens planet, Serpo, and spent more than a decade learning about the planet and its inhabitants, a race called the Ebens.
According to them, the Ebens lived in a peaceful, government-free community. After 13 years, the team finally returned to Earth four members short after two of them died and another two chose to stay on Serpo.
The conspiracy theory goes on to claim that such was America's leap in flight technology at that time that humans would have been unable to come up with these technologies in such a short space of time and they actually reverse engineered the crashed flying saucer.