This memo is out of this world. Mysterious sightings of ‘three to four-foot tall’ beings decked out in space suits and helmets were reported by witnesses decades ago, newly released Pentagon files reveal. The astonishing accounts were included in an internal FBI memo dated Oct. 19, 1966 with the subject line “Unidentified Flying Objects” — released to the public on Friday — that claims that “1965 was the year of the greatest number of UFO sightings.” A 1966 FBI memo that details UFO sightings and witnesses accounts sighting “four foot tall” beings in “space suits and helmets” was released today as part of the FBI’s file release on UFOs.…