June 24, 1947. One month before the Roswell UFO incident, Kenneth Arnold sighting became famous worldwide after claiming to have seen nine unusual objects flying in tandem near Mount Rainier, Washington.
In June 24, 1947, the civilian pilot Kenneth Arnold reported seeing nine objects, glowing bright blue-white, flying in a “V” formation over Washington’s Mount Rainier. He estimated the objects’ flight speed at 1700 mph and compared their motion to “a saucer if you skip it across water.”
In newspaper reports of Arnold’s sighting, this description was mistakenly taken to mean that the objects were shaped like saucers, leading to the popularization of the term “flying saucer” as a synonym for UFO.
Though Arnold said he initially thought what he had seen were test flights of military aircraft, the military later said they had been conducting no test flights during the time of the incident. A prospector on Mt. Adams saw the objects at around the same time as Arnold, bolstering his story.
Air Force investigators deemed both Arnold and the prospector to be credible witnesses, but concluded that what they had seen was a mirage, not actual flying ships.
This was the first post-War sighting in the United States that garnered nationwide news coverage and is credited with being the first of the modern era of UFO sightings, including numerous reported sightings over the next two to three weeks.
Arnold’s description of the objects also led to the press quickly coining the terms flying saucer and flying disc as popular descriptive terms for UFOs.