It could well have been a weather balloon gone astray, or a helicopter, he says, but it’s impossible to know at this point. “If you’ve got it in your head that aliens exist and that UFOs are visiting us, it’s quite logical then—if you’re of that age, and you’re quite suggestible, you’re going to see something and think it’s a flying saucer.”

But adults, he says, are just as suggestible as children. In 1976, a 27-year-old woman who was the daughter of a Royal Air Force captain was driving near London with her boyfriend when they both spotted a strange object, lit up with white lights, that passed overhead and appeared to be coming in to land. She filed a detailed drawing that showed the UFO from three vantages—straight on, from below, and as seen through the car windshield. Her report made its way to a secretive branch of the Ministry of Defense called D155, where, by consulting radar footage from the area, it was decided that the object was a Boeing 720 plane that had diverted from Gatwick airport at the same time. But she had been clear that the object had no wings, and stressed “it was nothing recognisable to me.”

Another image, known today as The Solway Spaceman, is a mysterious photograph that Carlisle fireman Jim Templeton took of his five-year-old daughter Elizabeth in the English countryside in May 1964. As the story goes, when Templeton came to pick up his developed film, the shop assistant said, “That’s a marvelous photograph, but it’s rather spoilt by the big man behind her!” Indeed, an unexplained figure dressed in a white astronaut suit loomed behind his daughter’s head. Neither the local Cumbrian police (nor the Kodak film company) could explain it. After the image was published in outlets around the world, Templeton reported being visited by two men in black suits and bowler hats. They drove a black Jaguar and said they were from “the Ministry” they asked to be taken to the site of the photograph.