A recent Nasa press conference detailing the American space agency’s research into UFO sightings sparked headlines across the globe about extraterrestrial visitors – but, as Dr David Clarke tells Matt Elton, such stories are nothing new. David explores how recent interest in UFOs fits into the longer history of our fascination with visitors from above, and what society’s shifting view of aliens tells us about the cultural and political currents of the 20th and 21st centuries.The HistoryExtra podcast is produced by the team behind BBC History Magazine and BBC History Revealed. Learn more about your ad choices. Visit podcastchoices.com/adchoices