An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon.\r \r Alien Cover Up : TOP SECRET DECLASSIFIED UFO Conspiracy Alien Cover Up : TOP SECRET DECLASSIFIED UFO Conspiracy According to Lundh, NASA .\r \r UFO Covered Up by the Government : Documentary on Government Conspiracy Cover-up of Aliens. .\r \r An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon.