Steven Spielberg is obsessed with UFOs. Indeed, judging by the success of his alien movies to date, his obsession is infectious. Perhaps more so than any other filmmaker, Spielberg has moulded our perceptions of otherworldly visitors. Films such as Close Encounters of the Third Kind (1977) and E.T.: The Extraterrestrial (1982) abound with iconic imagery seared into the minds of millions: a mothership’s miraculous ascension at Devil’s Tower; a boy and his fugitive friend from the stars cycling in silhouette across the face of the moon. Even Spielberg’s less memorable alien movies – War of the Worlds (2005) and Indiana Jones and the Kingdom of the Crystal Skull (2008) – have enjoyed enormous success at the worldwide box-office, raking in some $1.4 billion between them.