`  :``Impermanent`` has NEVER been a defining characteristic of UFOs, no matter who has studied the phenomenon during the last 60 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 can't find such a study because it doesn't 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 1950s for the USAF (3200 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.  `