UFOs: What Are They? - Chasing UFOs

UFOs: What Are They? - Chasing UFOs - National Geographic Channel: "What are UFOs, really? If you pose that question to a fervent believer who pours over testimonies from supposed alien abductees and reports of mysterious lights in the nighttime sky, you'll hear that they probably are spaceships from other worlds. A hard-core skeptic, on the other hand, is more likely to tell you about atmospheric conditions that produce false blips on radar, eager untrained observers who mistake aircraft lights or military flares for alien craft, and photos doctored by hoaxers."