People that fly unregistered or unapproved aircraft in monitored airspace. Unregistered aircraft is considered a UFO if it is in operation. (Just cause there is a UFO does not mean there are little green, cow probing people from other worlds inside.)
As far as what can possible be inside, Let the list begin!
1.) LITTLE GREEN MEN
2.) DRUGS
3.) LITTLE GREEN MEN ON DRUGS. (PLUTONIUM NIBORG) - Heavy Metal
4.)
Possibly, people have wondered if the pyramids were made by UFO's instead of the Egyptions. I don't really believe this.
Bigfoot is possibly an alien entity as illustrated by solid UFO cases.
possibly going into another dimension
We could be in for a rude awakening...
If you could feel a UFO, then you would be close enough to see what it was and it would no longer be unidentified. You would know what it was.
They could be because there are facts about UFO's.
People say in space but really UFO. Means unidentified. Fly object so like a Frisbee could be a UFO if u thinking UFO as in aliens those are not real at all.
Depends...... You could just throw a frisbee in the air, and it could be an UFO Or........... You could make a real jet powered one. You just need more resources, a intelligent mind, and of course a vast imagination!
Anything is possible.
I think there was but I could find no details.
You can't . UFO's could be an urban myth and there is no proof that they exist, Until Earth meets a real alien or finds a ship they will continue to be a myth.
UFO stands for, unidentified flying object, therefore any flying object not identified or recognized could be called a UFO, though that term is usually now a days used to describe a flying saucer. The UFO crew are ETS, or E.T.s ~ extraterrestrials.