unidentified flying object

Any light or object seen in the sky of which the immediate identity is not apparent. Despite unsubstantiated claims, there is no evidence that UFOs are alien spacecraft. On investigation, the vast majority of sightings turn out to have been of natural or identifiable objects, notably bright stars and planets, meteors, aircraft, and satellites, or to have been perpetrated by pranksters. The term flying saucer was coined in 1947.

In 1968, the US Air Force sponsored a scientific investigation of UFOs, and came to the conclusion that there was no extraterrestrial cause of these phenomena. Nevertheless, thousands of people in different parts of the world claim to have seen something they believed to be an alien craft. In the vast majority of cases, such objects are described as either cigar-shaped or saucer-shaped, resembling illustrations in old science fiction magazines.