There's an abundance of information on UFOs, but what is true and what is not? Possible visits from outer space have created a vast stream of misinformation, alternative facts and conspiracy theories. How do you know if any of it is true? What is flying through our skies? What do we know, how do we know it: science does not have all the answers, but it does have most. Scientists from all sorts of fields answer all sorts of questions, but mostly: Are we being visited?