In popular culture, UFOs most often mean an unidentified flying object, the appearance of which is associated with a visit to Earth by intelligent beings.
Many people, including officials and scientists, are skeptical about the possibility of these visits and are convinced (or, according to ufologists, pretend to be convinced) that UFOs are an abnormal natural or aerospace phenomenon.
On the contrary, some former officials, military and cosmonauts (including lunar astronaut Edgar Mitchell, who later became interested in parapsychology), after leaving the service, become public adherents of the alien origin of UFOs.