An unidentified flying object or UFO is a popular term for any aerial phenomenon whose cause cannot be easily or immediately determined. Popular culture frequently takes the term UFO as a synonym for alien spacecraft.
Unexplained aerial observations have been reported throughout history. Some were undoubtedly astronomical in nature such as comets, bright meteors, or atmospheric optical phenomena such as parhelia and lenticular clouds. Sightings throughout history were often treated as supernatural portents, angels, or other religious omens. Some objects in medieval paintings are strikingly similar to UFO reports. Art historians explain those objects as religious symbols, often represented in many other paintings during the Renaissance.
Carl Jung theorized that UFOs might have a primarily spiritual and psychological basis. He pointed out that the round shape of most saucers corresponds to a mandala, a type of archetypal shape seen in religious images. Thus the saucers might reflect a projection of the internal desires of viewers to see them. However, he did not label them as delusions or hallucinations outright, defining them as more in the nature of a shared spiritual experience.
However, Jung seemed conflicted as to possible origins. At other times he asserted that he wasn’t concerned with possible psychological origins and that at least some UFOs were physically real, based primarily on indirect physical evidence such as photographs and radar contact in addition to visual sightings. He also considered the extraterrestrial hypothesis to be viable.
It has been speculated that UFOs might have their origins not in space and time as we know it, but outside of it. There has been noted an almost exact parallel between UFOs and visitations from folklore of fairies and similar creatures. The significance of these parallels is disputed between mainstream scientists, who contend that they are fanciful demonstrations of a poorly understood phenomenon interacting with humans to cause the sightings.
Terence McKenna, in contrast, believed that UFOs are manifestations of the human soul, or collective spirit. He thought they appeared to individuals and groups in order to exert psychological influence over the course of history and might preside, in the year 2012, over history’s end.
A large part of the available UFO literature today is closely linked with mysticism and the metaphysical. It deals with subjects like mental telepathy, automatic writing and invisible entities as well as phenomena like poltergeist or ghost manifestations and possession. Many of the UFO reports now being published in the popular press recount alleged incidents that are strikingly similar to psychic phenomena.