In Brief:
Unidentified Flying Object, or UFO, an object or light that cannot be readily explained as being man-made or of natural origin. Tens of thousands of UFO reports have been made since that time, and it is likely that many thousands of additional sightings have been made but not reported. The great majority of UFO reports have proven to be of sightings of objects or natural phenomena unfamiliar to or unrecognized by the observer. Nevertheless, a small percentage of UFO reports made by credible witnesses remain unexplained.. Beginning in 1947, it collected and studied UFO reports under a program known as Project Blue Book.
