Why did Obama say aliens are real?

Barack Obama has caused a frenzy after saying he thinks aliens are real during a podcast interview. The former US president was forced to release a statement clarifying he had not seen any evidence of extraterrestrials. There is a long-running conspiracy theory claiming the US government is hiding extraterrestrials at Area 51, a highly classified air force site in Nevada. Lucy Hough speaks to the host of the Guardian’s Science Weekly podcast, Madeleine Finlay