Qu'est-ce (qui) est UFO - définition
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![CIA]] to declassify all documents with “historical value” that were at least 25 years old.](https://commons.wikimedia.org/wiki/Special:FilePath/CIA annotated drawing - dark grey solid looking UFO.webp?width=200 "CIA]] to declassify all documents with “historical value” that were at least 25 years old.")
![Ministry of Defence]] by RAF Fylingdales, 2004](https://commons.wikimedia.org/wiki/Special:FilePath/Close up of light in sky, Sri Lanka.jpg?width=200 "Ministry of Defence]] by RAF Fylingdales, 2004")
![The [[1561 celestial phenomenon over Nuremberg]] as printed in an illustrated news notice. UFO enthusiasts have described the phenomenon as an aerial battle of extraterrestrial origin. Skeptics argue that it was a [[sun dog]]](https://commons.wikimedia.org/wiki/Special:FilePath/Himmelserscheinung über Nürnberg vom 14. April 1561.jpg?width=200 "The [[1561 celestial phenomenon over Nuremberg]] as printed in an illustrated news notice. UFO enthusiasts have described the phenomenon as an aerial battle of extraterrestrial origin. Skeptics argue that it was a [[sun dog]]")
![A document about a sighting of a UFO that occurred on December 16, 1977, in the state of [[Bahia]], [[Brazil]]](https://commons.wikimedia.org/wiki/Special:FilePath/Registro de avistamento de Objeto Voador Não Identificado - OVNI ocorrido em dezembro de 1977, na Bahia.jpg?width=200 "A document about a sighting of a UFO that occurred on December 16, 1977, in the state of [[Bahia]], [[Brazil]]")
![Roswell]] Daily Record on July 8, 1947 reporting a UFO case](https://commons.wikimedia.org/wiki/Special:FilePath/RoswellDailyRecordJuly8,1947.jpg?width=200 "Roswell]] Daily Record on July 8, 1947 reporting a UFO case")
![A photograph of a purported UFO in [[Passaic, New Jersey]], taken on July 31, 1952](https://commons.wikimedia.org/wiki/Special:FilePath/Supposed UFO, Passaic, New Jersey.jpg?width=200 "A photograph of a purported UFO in [[Passaic, New Jersey]], taken on July 31, 1952")
![A UFO monument at [[Tenjo]], [[Colombia]]](https://commons.wikimedia.org/wiki/Special:FilePath/Tenjo Estatua UFO.JPG?width=200 "A UFO monument at [[Tenjo]], [[Colombia]]")
Wikipédia
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An unidentified flying object (UFO) is any perceived aerial phenomenon that cannot be immediately identified or explained. Upon investigation, most UFOs are identified as known objects or atmospheric phenomena, while a small number remain unexplained.
Scientists and skeptic organizations such as the Committee for Skeptical Inquiry have provided prosaic explanations for a large number of claimed UFOs being caused by natural phenomena, human technology, delusions, or hoaxes. Small but vocal groups of ufologists favour unconventional or pseudoscientific hypotheses, often claiming that UFOs are evidence of extraterrestrial intelligence. Beliefs surrounding UFOs have inspired parts of new religions.
While unusual sightings have been reported in the sky throughout history, UFOs became culturally prominent after World War II, escalating during the Space Age. The 20th century saw studies and investigations into UFO reports conducted by governments (such as Project Blue Book in the United States and Project Condign in the United Kingdom), as well as by organisations and individuals.
