In 1947 a crash landing occurred in Roswell, New Mexico, that people still talk about. According to many UFO believers, aliens from another world crash-landed their flying saucer, and the US government has tried to cover it up ever since.
This claim was given impetus with the release of a 1995 documentary that claimed to show genuine footage of autopsies on aliens that were recovered from the crash site. But the credibility of this film experienced its own 'crash landing' when one of the actors paid to take part in the documentary publicly confessed it was a hoax.
So what really did happen at Roswell? Well, 1947 was the beginning of the Cold War and the USA was secretly monitoring the Soviets via weather-type balloons with specialized monitoring equipment. When one crashed on a ranch at Roswell, they wanted to keep things secret so that the Soviets didn't know they were being spied on.