UFO

The word 'UFO' stands for 'Unidentified Flying Object', but has come in general usage to mean a spaceship from outer space, piloted by aliens, or non-human extraterrestrials. UFOs are often believed to be in the shape of flying saucers, but many other shapes have been reported, such as cigar shapes and triangles. The first modern sighting was made in 1947 by US pilot Kevin Arnold. Arnold's description of "flying saucers" entered the public imagination. That summer a flying saucer was alleged to have crashed at a town called Roswell, complete with miniature humanoid occupants. Many alleged sightings have been made since then, and many people claim to have been abducted by aliens and subjected to experimentation. Despite all these claims, no concrete evidence has ever emerged that aliens exist. Many alternative explanations for the abduction phenomena have been put forward by a number of people. Among the most prominent of these is "sleep paralysis," a sleep-related disorder which can induce sensations very similar to those reported in abductions, posited by Carl Sagan, well-known for his thoughts on extraterrestrial life. Many conservative Christians believe that UFOs can be explained by 'false messiahs and false prophecies' as predicted to come by Christ.