Are we alone in the universe? Although Johannes Kepler may have asked this question centuries ago, the invention of radio, interplanetary travel and precision telescopes have given modern civilization the tools to perhaps realistically answer this question. But some people allege that the answer to that question is already known and that aliens do exist, and many cite various sightings of unidentified flying objects (UFOs) as proof. Thousands claim to have seen unidentified flying objects (UFOs) around the world, many of which have been explained and some that have remained more mysterious. What are UFOs? What is Area 51? Find out answers to these questions and more in How UFOs Work.