Unidentified Flying object(UFO), any object or light, reportedly sighted in the sky that cannot be immediately explained by the observer. Sightings of unusual aerial henomena date back to ancient times but UFOs(sometimes called flying saucers became widely discussed only after the first widely publicized U.S. sighting in 1947. Many thousands of such observations have since been reported worldwideUnidentified Flying Object (UFO), any object or light, reportedly sighted in the sky, that cannot be immediately explained by the observer. Sightings of unusual aerial phenomena date back to ancient times, but UFOs (sometimes called flying saucers) became widely discussed only after the first widely publicized U.S. sighting in 1947. Many thousands of such observations have since been reported worldwide