Did aliens really come to earth?

People who think they have seen UFOs have only seen something in the air that they can't identify. Just because they can't explain what they've seen does not mean it is an alien space ship.

Although many people equate UFOs as something from outer space, there has never been any credible proof that there is such a thing. If aliens have come from outer space, there has never been any credible proof or evidence of that either.