Unidentified flying object is the popular term for any apparent aerial phenomenon whose cause cannot be easily or immediately identified by the observer. The United States Air Force, which coined the term in 1952, initially defined UFOs as those objects that remain unidentified after scrutiny by expert investigators, though today the term UFO is colloquially used to refer to any unidentifiable sighting regardless of whether it has been investigated.

What is your stand on thi one? I think we aren't the only ones out there in our vast space.