The possibility of extraterrestrial life is not, by itself, a paranormal subject. Many scientists are actively engaged in the search for unicellular life within the solar system, carrying out studies on the surface of Mars and examining meteors that have fallen to Earth. Projects such as SETI are conducting an astronomical search for radio activity that would show evidence of intelligent life outside the solar system. Scientific theories of how life developed on Earth allow for the possibility that life developed on other planets as well. The paranormal aspect of extraterrestrial life centers largely around the belief in unidentified flying objects and the phenomena said to be associated with them.
Early in the history of UFO culture, believers divided themselves into two camps. The first held a rather conservative view of the phenomena, interpreting them as unexplained occurrences that merited serious study. They began calling themselves «ufologists» in the 1950s and felt that logical analysis of sighting reports would validate the notion of extraterrestrial visitation.
The second camp consisted of individuals who coupled ideas of extraterrestrial visitation with beliefs from existing quasi-religious movements. These individuals typically were enthusiasts of occultism and the paranormal. Many had backgrounds as active Theosophists, Spiritualists, or were followers of other esoteric doctrines. In contemporary times, many of these beliefs have coalesced into New Age spiritual movements.
Both secular and spiritual believers describe UFOs as having abilities beyond what are considered possible according to known aerodynamic constraints and physical laws. The transitory events surrounding many UFO sightings also limits the opportunity for repeat testing required by the scientific method. Acceptance of UFO theories by the larger scientific community is further hindered by the many possible hoaxes associated with UFO culture.