UFO, (commonly known as a "flying saucer"), is the abbreviation of Undentified Flying Object, which refers to all kinds of uninvestigated or unidentifiable flying objects; unidentified flying objects identified by experts and scientific researchers. This word first appeared in the US Air Force investigation report in the 1940s.
The event marking the beginning of the modern UFO era:
In 1947, Kenneth Arnold, a businessman from Idaho, USA, saw nine neatly arranged flying saucers while flying his private plane across the Cascade Mountains in Washington State. A few days later, mysterious metal fragments were discovered in Roswell, New Mexico.
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