There is no UFO and also there is no alien, at least not in common mind nor reference.
Betelgeuse Incident: Insiden Bait Al-JauzaThat really pissed me off, because I am worth it, goddamn it!” “I know you—” “Still talking here!
Alien OvernightMy airplane is quiet, and for a moment still an alien, still a stranger to the ground, I am home.
Stranger to the GroundHey, Geekoid!" yelled Duncan Dougal, "Why do you read so much? Don't you know how to watch TV?
My Teacher is an Alien