Are we alone in the universe? It's a question that humanity has long grappled with. But while astronomers continue to scan the cosmos for signs of alien life, imaginations are free to run wild here on Earth. From pop stars to Hollywood actors to politicians, here are 13 famous people who believe in aliens.
History remembers Winston Churchill for his political prowess and his leadership during a complex time in Britain's history, but a relatively unknown part of the statesman's legacy — one in which he confronted the idea of alien civilizations — was recently uncovered.
Churchill penned an 11-page essay on alien life in 1939, revealing his curiosity about the universe and outlining his definition of life and its most important ingredients.
"I, for one, am not so immensely impressed by the success we are making of our civilization here that I am prepared to think we are the only spot in this immense universe which contains living, thinking creatures," he wrote in the newly uncovered essay, "or that we are the highest type of mental and physical development which has ever appeared in the vast compass of space and time."
Churchill's essay was described in an article published in the journal Nature in February 2017.
It can be hard keeping up with the Kardashians' exploits, but when it comes to aliens, at least one member of the famous family is a believer. In 2015, Khloe Kardashian saw strange lights in the sky and tweeted "Kendall and I are spazzing out!!!!!! #UFO."
Though the U.S. Navy later said the unusual lights were part of a pre-planned missile test, Kardashian stuck to her guns.
"What do we expect people to say? Obvi they are going to say it's a meteor shower. I'm such a conspiracy theorist let me enjoy this," she responded.
Hillary Clinton has a long political history advocating for children and families, gender equality and health care reform, but in 2016, during her bid to secure the Democratic nomination for president, Clinton turned her attention to the paranormal.
In a radio interview and then later on "Jimmy Kimmel Live," Clinton said she wants to review files about UFOs and the mysterious Area 51 site in Nevada and make them public.
"I would like us to go into those files and hopefully make as much of that public as possible," she told Kimmel. "If there's nothing there, let's tell people there's nothing there."
Area 51, located about 80 miles (130 kilometers) northwest of Las Vegas, in the Nevada desert, is a restricted military outpost that is part of the Edwards Air Force Base. It has been the site of a number of stealth military programs, and this secrecy has, in part, fueled conspiracy theorists who claim that scientists at the facility are reverse-engineering alien technology from UFO crashes. In 2013, declassified CIA documents detailed some of Area 51's history, revealing the site's role in testing spy planes such as the U-2. There was no mention of aliens or UFOs in the declassified files.
Singer Zayn Malik told Glamour in July 2016 that the first time he realized he wanted to leave the boy band One Direction and go solo was after a paranormal encounter. "An alien spoke to me in a dream," he told the magazine.
Malik is in a relationship with model Gigi Hadid, who recently posed for a space-themed photo spread for Harper's Bazaar. "My boyfriend's really into aliens," Hadid told the interviewer from Harper's Bazaar during the photo shoot at NASA's Kennedy Space Center in Florida.
It's always better when two people in a relationship are on the same page about important issues. For model Gigi Hadid and her boyfriend, singer Zayn Malik, their shared belief in aliens makes them a match made in … the cosmos?
In a recent, space-themed photo spread for Harper's Bazaar, Hadid posed at the controls of a spacecraft, in front of massive rockets and rocket engines, and on what's made to look like the lunar surface. In the Harper's Bazaar interview, Hadid revealed that she and Malik both believe that life exists beyond Earth.
"My boyfriend's really into aliens," she told the magazine.
Singer Ariana Grande has described herself as "obsessed" with aliens, and in a 2013 interview with Complex magazine, the pop powerhouse said, "We'd be so stupid to believe we are the only people here."
Grande's music video for the song "Break Free" featured her battling aliens and dancing on a spaceship. But Grande told Complex she has never seen a real extraterrestrial (though she said she did have a ghost and demon experience once at a haunted castle in Kansas City).
Film director Ridley Scott is no stranger to the concept of alien invasions and hostile encounters with extraterrestrials. His 1979 movie "Alien" explored the scary concept of an aggressive extraterrestrial that targets the crew of a spaceship. The film spawned a franchise with three sequels and two prequels, including "Alien: Covenant," which opens in theaters in the U.S. on May 19, 2017.
While promoting the new film, Scott warned that hundreds of alien species are "out there" and cautioned that humans likely won't fare well if these cosmic interlopers ever decide to pay a visit to Earth.
"If you are stupid enough to challenge them, you will be taken out in three seconds," Scott told the Agence France-Presse (AFP).
Actress Gillian Anderson is best known for playing FBI Special Agent Dana Scully on the hit sci-fi series "The X-Files." But while Anderson spent nine seasons investigating paranormal phenomena on the small screen, does she believe in aliens in real life?
"I do to the degree that the universe is obviously vast and the thought that we are the only planet full of living beings doesn't make sense," Anderson said in an interview with The Guardian in 2012. "That doesn't necessarily mean that there are aliens, but there could be. If we're talking about an advancement of technology, that they'd be potentially further along than us is as conceivable as their existence. So I wouldn't rule it out."
In a 2014 interview with GQ, pop star Katy Perry spoke about her wide range of beliefs.
"I see everything through a spiritual lens," she told GQ. "I believe in a lot of astrology. I believe in aliens. I look up into the stars and I imagine: How self-important are we to think that we are the only life-form?"
At the time, Perry said she might even take her questions about alien life to then-President Barack Obama.
"I mean, if my relationship with Obama gets any better, I'm going to ask him that question. It just hasn't been appropriate yet."
In an interview with the British talk show "The Morning," singer Nick Jonas described his own close encounter.
"I was in my backyard in L.A., and I looked up at the sky and [saw] three flying saucers," Jonas said. "I looked at my friend and said, 'Are you seeing this or am I losing my mind?'"
Jonas said he looked online and saw three similar reports from two weeks earlier. The U.S. Navy later claimed responsibility for the seemingly out-of-this-world display, saying the lights were from a Trident missile test. But Jonas has other ideas.
"I'm obsessed with UFO stuff in general, so I'm all over this," Jonas said. "That blue light freaks me out in the best way possible."
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Denise Chow was the assistant managing editor at Live Science before moving to NBC News as a science reporter, where she focuses on general science and climate change. Before joining the Live Science team in 2013, she spent two years as a staff writer for Space.com, writing about rocket launches and covering NASA's final three space shuttle missions. A Canadian transplant, Denise has a bachelor's degree from the University of Toronto, and a master's degree in journalism from New York University.