The modern UFO phenomenon began in 1947 with the eyewitness account of pilot Kenneth Arnold of nine flying disks near Mount Rainier in Washington. The newspapers called them flying saucers. UFO is the more technical term, standing for unidentified flying object. A sighting acquires this designation only after scientific attempts to identify it as a star, meteor, balloon, aircraft, or hallucination have failed. UFO refers to what is unidentified after attempts to identify it.

Types of sightings

As a phenomenon of perception, scholars study both the perceiver and the perceived, both the UFO and its witness. Sightings are classified as: (1) daylight disks; (2) nocturnal lights; (3) radar sightings or combinations of radar and visual sightings; (4) close encounters of the first kind, when the witness is within 500 feet of the object or craft; (5)...