The 'Star of Bethlehem', also called the 'Christmas Star', is one of the world's greatest mysteries and one of the most important Christian symbols. It led the Magi on a search for a new Messiah, yet nobody else saw it. Was it a spectacular comet, a blazing supernova, or an astrologically significant alignment of planets? Gathering evidence from Bethlehem to Babylon, the catacombs of Rome to the vaults of the British Museum, this is a quest to uncover the celestial truth behind this most famous of stars. What did the Magi really see 2000 years ago?