UFOs
"UFOs" are, by definition, "unidentified." In otherwords, we have virtually no reason whatsoever to believe that they are spacecraft containing extraterrestrial visitors.
To date, not a single UFO sighting has been identified as an alien vehicle from outer space. To date, we have not a single shred of documented and independently verifiable evidence that E.T. is dropping in on us with plans to phone home soon.
