Impermanent has NEVER been a defining characteristic of UFOs no matter who has studied the phenomenon during the last  years  Now ScienceApologist personally decides that impermanant is a defining characteristic of UFOs  What is this based on other than his own personal biases and obvious ignorance of the subject matter  I would like to see a genuine reference to a study that shows that UFOs have less permanence than prosaic identified phenomena such as meteors or jet planes flying overhead  You know the verifiability thing  You cant find such a study because it doesnt exist  In fact UFOs are no more impermanent than the things that are considered to be identified  When Battelle Memorial Institute scientists investigated duration of sightings in the s for the USAF  cases they found that if anything unidentified sightings tended to have slightly longer durations than the identifieds  This was a highly statistically signficant finding  There are sightings that go on for hours even days sometimes  No way should impermance or any similar word be part of the UFO definition