Look up "Project Mogul" in Wikipedia, This UFO stuff is just a sick PsyOp being played on gullible people. Do you seriously think that aliens sophisticated enough to cross light-years of space, wouldn't know how to avoid crashing on the Earth? Frankly, I don't think they bother travelling at all, they just share knowledge via virtual reality and such. I will be a fantastic day when we figure out how to join in on this rich helping of advanced knowledge. But I am not holding my breath ...