The initialisation UFO means Unidentified Flying Object.
That's an object that's flying (or appears to be flying) that hasn't been identified.
That may seem a patronising thing to say but it seems many people need this explaining to them.
So to the layman a meterior storm might be a UFO, to a pilot a prototype aircraft might a UFO and to a conspiracy theorist a blurry picture of chicken feeder being hung on a wire might be a UFO.
My point is just because something is a UFO that doesn't suggest in any way it must be an alien space craft.
Could these UFO's be alien space craft well it certainly begs a few questions. I mean we had technology that could make a large plane appear the size of a bee on radar in the late 50's and satilites that can read the print off newspapers from space not long after. To think that an alien race has mastered the time issue of intergalactic flight and then done the following:
a: Affixed their undercover survalience craft with bright lights
b: Made the mistake of landing on crop fields and leaving a impression numerous times
c: Crashing into a desert and not fitting ejector seats
d: Decided that the only people worth probing with paraniod American rednecks
That's all a tad far fetched imo.