On June 24, 1947, private pilot Kenneth Arnold reported seeing nine unusual, brilliantly fast-moving objects flying in formation near Mount Rainier, Washington. His description of the objects' motion as being like "a saucer if you skip it across water" led to the press coining the term "flying saucers," igniting a worldwide phenomenon.1 The sighting is widely regarded as the start of the modern UFO era and led to a surge of reports and official investigations.2
The Sighting
While flying his CallAir A-2 on a business trip, Arnold diverted to search for a missing military transport plane.3 At approximately 3:00 PM, he witnessed a bright flash followed by a chain of nine crescent-shaped objects flying in a "V" formation.4 He estimated their speed at over 1,500 miles per hour, a velocity unheard of for any known aircraft at the time, by timing their passage between two mountain peaks.5 The objects weaved in and out of the Cascade Mountain peaks, moving with a distinct, skipping motion.
Investigation and Legacy
Arnold's report was quickly picked up by news services and spread nationwide, triggering hundreds of similar reports in the following weeks.6 The U.S. Army Air Forces interviewed Arnold and, while finding him credible, ultimately concluded the sighting was a mirage caused by temperature inversions.7 Other explanations have included misidentified meteors or a flock of American white pelicans.8 Despite official explanations, the event established the "flying saucer" as a cultural fixture and prompted the creation of the Air Force's first formal UFO investigation, Project Sign.9