UFO

A term originally coined by the military, an unidentified flying object (usually abbreviated toUFO or U.F.O.) is an unusual apparent anomaly in the sky that is not readily identifiable to the observer as any known object. While a small percentage remain unexplained, the majority of UFO sightings are often later identified as any number of various natural phenomenon or man-made objects.^{[citation needed]}
While technically a UFO refers to any unidentified flying object, in modern popular culture the term UFO has generally become synonymous with alien spacecraft. Proponents argue that because these objects appear to be technological and not natural phenomenon, and are alleged to display flight characteristics or have shapes seemingly unknown to conventional technology, the conclusion is then that they must not be from Earth.^[1][2][3][4] Though UFO sightings have occurred throughout recorded history, modern interest in them dates from World War II (seefoo fighter), further fueled in the late 1940s by Kenneth Arnold's coining of the term flying saucer and the Roswell UFO Incident. Since then governments have investigated UFO reports, often from a military perspective- and UFO researchers have investigated, written about, and created organizations devoted to the subject. One such investigation, The UK's Project Condign report, notes that Russian, Former Soviet Republics, and Chinese authorities have made a co-ordinated effort to understand the UFO topic and that State military organizations, particularly in Russia, have done "considerably more work (than is evident from open sources)" on military applications which have stemmed from their UFO research. The report also noted that "several aircraft have been destroyed and at least four pilots have been killed 'chasing UFOs'."^[5]

Studies have established that the majority of UFO observations are misidentified conventional objects or natural phenomenon— most commonly aircraft, balloons, noctilucent clouds, nacreous clouds, or astronomical objects such as meteors or bright planets with a small percentage even being hoaxes.^[8] After excluding incorrect reports, however, it is acknowledged that between 5% and 20% of reported sightings remain unexplained, and as such can be classified as unidentified in the strictest sense. Many reports have been made by trained observers such as pilots, police, and the military; some involve radar traces, so not all reports are visual.^[9] Proponents of the extraterrestrial hypothesis believe that these unidentified reports are of alien spacecraft, though various other hypotheses have been proposed.

While UFOs have been the subject of extensive investigation by various governments, and some scientists support the extraterrestrial hypothesis, few scientific papers about UFOs have been published in peer-reviewed journals.^[10] There has been some debate in the scientific community about whether any scientific investigation into UFO sightings is warranted.^{[11][12][13][14][15][16][17]}

The void left by the lack of institutional scientific study has given rise to independent researchers and groups, most notably MUFON (Mutual UFO Network) ^[18] and CUFOS (Center for UFO Studies).^[19] The term "Ufology" is used to describe the collective efforts of those who study reports and associated evidence of unidentified flying objects. According to MUFON, as of 2011 the number of UFO reports to their worldwide offices has increased by 67% from the previous 3 years, which now average around 500 reported sightings per month.^[20]

UFOs have become a relevant theme in modern culture,^[21] and the social phenomena have been the subject of academic research in sociology and psychology.^[10]