But in real life, between 3,000 and 4,000 sightings are documented in the U.S. every year, according to the "National UFO Reporting Center." Even President Jimmy Carter claimed to have a close encounter and, as a congressman, Gerald Ford pressed for a UFO investigation. More recently, a sighting last November at O'Hare airport made the front page of the Chicago Tribune.
So where can you hope to spot E.T.? Start in Roswell, N.M. From its local restaurants to its alien head lamp posts to its space-aged McDonald's, the town is like an intergalactic shrine. The main attraction, of course, is the international UFO Museum where Julie Shuster is the director.
"A majority of the people that come through our doors believe there is more out there. That there is life out there — that UFOs and extraterrestrial are totally plausible," she told CBS News technology correspondent Daniel Sieberg.
Roughly 2.5 million earthlings have visited this Roswell institution since its inception in 1992. That's about 160,000 every year. They've come from all 50 states and 35 countries. Some are just curious while others are firm believers.
"I was awakened in the middle of the night, the curtains were just glowing orange and just pulsating, and this loud noise humming sound, I got up and went to the window and looked out and there was one big as this ceiling hovering above my junkyard," Museum Visitor Dwaine Grammer said.
Shuster says they hear stories like this a lot.
"We get abductions," she said. "We had a man from Australia that came in, who felt he had been abducted. We got him in touch with a leading UFO abduction researcher. That's what we do."
But perhaps the most famous incident of all occurred in Roswell 60 years ago, when a local rancher heard an explosion and found mysterious debris on his property. Experts from the nearby Army air field were called in. Shuster's father was the public information officer.
"On July 8, 1947, he issued a press release under orders from Colonel William Blanchard, saying basically, 'We have in our possession a flying saucer,'" Shuster said. "Then on July 9th, 1947, General Rayme out of Fort Worth, issued the story that, 'No, it was a weather balloon.' And the story was kept quiet until 1979, when the first book was issued."
Nuclear physicist Stanton Friedman, a preeminent UFO Researcher, co-authored a book on Roswell, says maybe human beings are not the masters of the universe and maybe there are other civilizations out there.
"We know that the government knows a great deal about it and has kept it secret, successfully, for 60 years," he said. "We know that there's proof positive that the planet's being visited, that the government is lying."
The government eventually admitted that the crash stemmed from a top-secret effort to monitor Soviet-era nuclear testing.
"So the fact they lied and said it was a weather balloon instead of a Cold War technology does not make it an alien spacecraft," Michael Shermer, founder of the Skeptics' Society and publisher of Skeptic magazine, said. "When UFOlogists say, 'You know the government lies to people,' Well, no kidding. I mean you needed UFOs to understand that?"
But Friedman, who has spent the last three decades lecturing on why space aliens are real, doesn't buy it. He conducts his lectures armed with photographs of alleged UFO sightings, which are all saucer shaped.
"Well, if you want an ideal flying vehicle, think about it," he said. "It can literally fly circles around anything we got flying, but it can hover, move straight up, straight down. We don't have things that can do that."
Many of the images also appear grainy. Friedman says that doesn't mean they are not real.
"Absence of evidence is not evidence of absence, now there's good reason," he said. "I talked to a cop who was standing outside his police car, always has a camera in the car, traffic accidents, that sort of thing. Saucer comes. Goes right over the car. Is he thinking about the camera? Heck, no. He's astonished by the saucer."
Shermer says he receives a lot of mail from people who say they had encounters with UFOs at 3 a.m. while driving down a deserted rural road, where it always seems to happen.
"It's not like, 'I was sitting there in Dodgers Stadium with 50,000 other people, Barry Bonds is up to bat and a UFO came over,' you know," he said. "Why does that never happen?"
But Friedman is an unwavering believer and says we don't understand what aliens are doing because they are here for their own purposes, not to satisfy us. He is not alone in his convictions. A CBS News poll last year revealed that one in five Americans believe that intelligent beings from other planets have made contact with humans on earth. And almost half of all Americans think there is intelligent life beyond our planet.
"Any day now we could have an existential shock when it's announced that scientists have identified an earth-like twin in outer space," said Professor Michio Kaku, a theoretical scientist at City College. "A new wave of satellites is going up in orbit, which could settle the question once and for all. And we hope to find other planets with liquid oceans that can perhaps recreate the conditions for life that we found on the planet Earth."
Even before we find that life, Kaku says, it may already have found us.
"I've looked at a lot of UFO sightings and the one that really sends shivers up your spine is the famous JAL sighting," he said. "We had a JAL, Japan Airlines airliner, where the pilots, seasoned Japanese pilots, saw something in the distance. It was tracked by radar."
For now, the most definitive UFO sightings remain at the movies, where aliens are not shy about making themselves known. Shermer says he needs concrete proof to believe they exist in real life.
"I say the same thing to the alien abductees and the UFOlogists that I say to the Big Foot people and the Lock Ness people," Shermer said. "Fine, you might be right, but show me the body. Where is the Big Foot body? Where is the Lock Ness creature's that we can dissect and take a photograph of. Put it in National Geographic. Everybody can study it."
But even though Friedman has never himself seen a UFO or alien, he remains focused on proving their existence.
"I chased neutrons and gamma rays for 14 years; I never saw one," he said. "I can't give you one and say, 'Here's what I'm talking about. Well, they're there, but you can't see 'em. Don't worry about it.' I've never seen Tokyo. It's there. Most of us learn about the world, not by first-hand experience. And so, I don't need to see a flying saucer."
For Julie Schuster, the proof is simple: "My daddy said – and my dad never lied – he said it was real."