Unexplained sightings have appeared in our skies for years, and now the U.S. government has started releasing declassified files about what we used to call UFOs. What explains these phenomena, and what do we know about life beyond Earth? Horizons moderator William Brangham explores what we do know, and what we don't, with Leslie Kean and Garrett Graff, two authors who've studied this topic deeply. PBS News is supported by - https://www.pbs.org/newshour/about/funders. Hosted on Acast. See acast.com/privacy