The kid knew his teacher was wrong. And looking back, there was never really a chance that he would let it go. It was the middle of the school year, 1943, and Mrs. Rose Gutkin was giving her fifth graders in Linden, New Jersey, an astronomy lesson: the sun, she explained, remains motionless, and all the planets orbit around it. But Stanton Friedman had just read in his encyclopedia that the whole solar system, including the sun, orbits the center of the galaxy. "At 12 miles a second," he says. "That impressed the heck out of me. I mean, that's fast."

So Friedman raised his hand, corrected his teacher, and got a dressing-down. The next day he brought the encyclopedia to school. "And she reluctantly agreed that, well, maybe that's the way it was."

Almost seven decades later, Friedman, SB'55, SM'56, still tells this story—in vivid, exuberant detail—to give people a sense of who he is: a methodical researcher, a steadfast debater, an investigator, a scholar. A scientist.

He's gotten used to proving his qualifications, convincing people that he's serious and, occasionally, that he's sane. Since 1970 Friedman, who half a lifetime ago worked as a nuclear physicist with a government security clearance, has been a full-time ufologist—that is, someone who studies unidentified flying objects. In national archives and presidential libraries, Friedman pores over declassified documents and scientific reports on UFO sightings and unexplained aerial events. At times his job is not unlike detective work: tracking down witnesses and collecting their testimony, chasing leads that turn up in his reading or that come to him, as they sometimes do, from someone confiding a name or a place or a piece of evidence. Friedman claims to be the "first civilian investigator" at Roswell, New Mexico, where many people believe that in July 1947 a spaceship crashed in the desert. Indeed, it was largely Friedman's digging, starting in the late 1970s, that brought widespread attention to Ros­well, an incident that had been all but forgotten.

His books have titles like Flying Saucers and Science: A Scientist Investigates the Mysteries of UFOs and Crash at Corona: The US Military Retrieval and Cover-Up of a UFO. His television appearances are myriad—Unsolved Mysteries, History Channel documentaries, network interviews on Nightline and CBS Sunday Morning. Friedman was a guest on three Larry King Live shows dedicated to UFOs, where he sat shoulder to shoulder with disbelievers and witnesses, wearing his usual dark suit and red pocket square, his wild wiry eyebrows flashing above excitable green eyes. "Physical trace cases, radar variable sightings—evidence!" he boomed during a 2007 show, squalling with UFO skeptic Michael Shermer. "You don't talk about evidence!"

But the cornerstone of Friedman's career is something much simpler: a series of slides and a stack of lecture notes. He spends months every year traveling to classrooms, conference halls, and auditoriums around the world, giving a lecture called "Flying Saucers ARE Real." The evidence is overwhelming, he says, that the planet is being visited by extraterrestrials, and that the US government is covering it up. And he'll debate anyone, anywhere, who argues otherwise.

This past July, Friedman turned 77. He figured he'd be retired by now. But seeing his eyes widen when he imagines alien sojourners propelling themselves to Earth in nuclear rockets ("Fusion! Every astronomer in the world knows that's what powers the stars, but they never give a thought to using it for a propulsion system"), or hearing story after story tumble out of him—the day he found out about Roswell and went searching for the only witness whose name he knew, the first time he looked up from a podium and saw 400 people looking back—it's hard to believe that he could ever retire.

Friedman lives in Fredericton, Canada, a university town straddling the St. John River, 60 miles north of Maine. His living room is bright and floral, its walls and tabletops adorned with family photographs and watercolors painted by his sister-in-law. Most are cheerful tableaus: Friedman and his second wife, Marilyn; his three children from his first marriage; his daughter from his second; his 24-year-old grandson; and his great-grandson, James.

His basement study is a different scene altogether: a riot of strewn papers, sprung-open filing cabinets, and groaning bookshelves. Against one wall, rolls of paper held together by rubber bands are stacked up like ancient scrolls. Friedman's desk and computer occupy a small, semicleared oasis by the door. "See," he says, surveying the chaos, "what I really needed was a secretary."

Friedman and Marilyn, a New Brunswick native, moved to Fredericton 30 years ago, and since then he's become a local celebrity. Mayor Brad Woodside, who declared August 27, 2007, Stanton Friedman Day, wishes his famous citizen would mention Fredericton more often on television. "He's a scientist, and a good one," says Rod Cooper, a computer-science professor at the University of New Brunswick. As a college student decades ago, Cooper saw a UFO as he crossed a toll bridge on his way to his parents' home in Niagra Falls. Five bright objects appeared in the distance, flying in a V. At first he thought they were Piper Cubs, but in an instant they were right overhead. "Amazingly close," he says, and amazingly fast. Then just as suddenly they were gone. At the tollbooth people were standing beside their cars, looking up. "I think it's very important," Cooper says, "to have people like Stan who take a very objective, scientific research view of this thing."

"Respected by all, ridiculed by some, loved by others," is how Roderick Nolan, Friedman's friend and sometime boss, sums up his hometown reputation. A founding executive at a Fredericton engineering and consulting firm where Friedman freelanced a few projects, Nolan remembers the time a few of the company's technicians climbed onto the roof to dangle a fake flying saucer outside Friedman's office window. "He came in one morning and it was hanging there," laughs Nolan. "All in good fun."

An impulse buy set the trajectory for Friedman's life's work. He needed one more volume to round out an order from a discount bookseller in New York so he wouldn't have to pay the postage. It was 1958, and Friedman, two years out of grad school at the U of C, was married and living in Cincinnati, working at General Electric on aircraft nuclear propulsion systems.

The title that caught his eye was a hardcover marked down to $1 called The Report on Unidentified Flying Objects, by Air Force captain Edward J. Ruppelt. The first chapter opened with a jolt: "In the summer of 1952, a United States Air Force F-86 jet interceptor shot at a flying saucer. This fact, like so many others that make up the full flying saucer story, has never before been told." In the early 1950s, Ruppelt—who coined the term "unidentified flying object"—headed Project Blue Book, a group of high-ranking military officers convened to analyze UFO sightings and determine if the mysterious things in the sky posed a threat to national security. By the time Project Blue Book folded in 1969, it had evaluated 12,618 reports of sightings.

Friedman found Ruppelt's book intriguing, if not entirely convincing. But he was curious enough to keep UFOs on his reading list. In 1959 a job with Aerojet-General Nucleonics brought him to Northern California, where a local librarian fed him book after book on flying saucers. "I must have read 15," he says. By that time he was more than intrigued.

Then he made what he calls one of the "big discoveries" of his life: Project Blue Book Special Report Number 14, a vast statistical analysis of 3,201 UFO cases, with hundreds of graphs, tables, charts, and maps. "I was in data heaven," Friedman says. According to the report, about 22 percent of sightings were declared "unknown." That means their origin couldn't be determined even after all the evidence was in—these were objects that didn't look like airplanes or balloons or any other discernible vessel. They maneuvered in strange ways, hovering or changing speed and direction suddenly. Sometimes witnesses, many of them Air Force pilots, described seeing actual saucer- or cigar-shaped objects.

Unknowns tended to be cases with better information: 35 percent of "excellent" sightings—those with more reliable witnesses and, sometimes, corresponding physical evidence—defied explanation; only 19 percent of poor ones did. And the longer a sighting lasted, Friedman says, the more likely it was to remain unexplained: 36 percent of unknowns were seen for more than five minutes. In Project Blue Book Special Report Number 14, Friedman found facts, numbers, evidence to hang his conclusions on. "I'm the Ralph Nader of UFOs," he once told a newspaper reporter, "not the Billy Graham."

The report, which omitted classified information, was released to the public in 1955, and it came with a summary that quoted the Secretary of the Air Force: "On the basis of this study, we believe that no objects such as those popularly described as flying saucers have overflown the United States." But Friedman knew that assertion plainly contradicted the numbers in the report. "Now, I was working under security, and sometimes you've got to tiptoe around the truth a little bit," he says, "because you can't release classified information. But I'd never run across a situation where someone in authority in a very widely distributed press release was lying through his teeth."

Not only was he now certain that aliens had visited Earth, Friedman also was convinced that the US government was hiding what it knew. "I was shook up," he says. He joined national UFO organizations and began corresponding with authors who'd written about flying saucers. His family moved from California to Indianapolis, and then in 1966 to Pittsburgh, where Friedman worked on nuclear rockets at Westinghouse Astronuclear Laboratory. He read more UFO reports. "In every large-scale scientific study," says Friedman, whose lectures cite five—including one by Northwestern astronomer J. Allen Hynek, SB'31, PhD'35—"20 to 25 percent of the cases can't be explained. That's a lot."

In Pittsburgh Friedman's fascination became a calling. He and a few others founded a UFO group and set up a 24-hour hotline people could call to report a sighting. "We hoped to get a team there while it was still happening," Friedman says. They never quite did. "Got there within ten minutes once. Just after it was over."

In fact, one of the world's foremost experts on flying saucers has never seen one, although for a moment a few years ago he thought perhaps he had. Friedman was filming a TV spot on an unlit New Hampshire road where, in 1961, a couple named Betty and Barney Hill claimed to have been abducted by a UFO while driving home from Quebec. (Friedman coauthored Captured!, a book on the abduction, with the Hills' niece, Kathleen Marden.) As the film rolled, the cameraman looked up and said, "What's that?" Friedman turned to see a mysterious light rise and then darken in the gloomy distance. And then another, and then another. But a little sleuthing revealed a terrestrial source. "We think it was battlefield flares dropped by the Vermont National Guard," Friedman says, shrugging. "That's the closest I've come."

In 1968 Friedman did his first radio show and gave his first UFO lecture at a book-club meeting in a Westinghouse colleague's living room. "I came up with some slides and everything." He got on the roster of a lecture series at Carnegie Mellon University, and afterward the Engineering Society of Detroit booked him for a dinner lecture. The event sold out three weeks in advance, all 1,008 seats.

By 1969, when Westinghouse laid Friedman off and, he says, "the bottom began falling out of the advanced nuclear and space systems business," the UFO business was booming. His side schedule bustled with lectures and radio appearances. A crowd of 500 nuclear society members came to hear him speak at New Mexico's Los Alamos National Laboratory. When he addressed a joint meeting of Pittsburgh's aeronautics and electrical engineering institutes, people stayed so late, "the janitor had to kick us out."

More than 700 lectures and untold miles later, he's still on the road. In the beginning he went wherever his cold calls could open a door to a lecture hall or a classroom, no matter how obscure the college or how small the town. He's spoken at Cornell and Harvard, but also at Cayuga Community College in Auburn, New York, and Midland Lutheran College in Fremont, Nebraska. These days Friedman travels to conventions and talks around the globe: Saudi Arabia, Brazil, Korea, Italy, Australia, Finland, China.

What first drew him to UFOs were the stories: mysterious objects appearing on air traffic controllers' radar screens in places where the sky was empty of airplanes, World War II bombers seeing strange metallic spheres and colored balls of light, Air Force pilots engaging with phantasms they could sometimes photograph but never catch. "I have had people quietly tell me," Friedman says, "about cases in which a pilot went up to chase UFOs," with orders to shoot them down. On at least seven occasions, he says, pilots went up but never came back.

The stories are endless. In 1950 a couple in McMinnville, Oregon, took two famous pictures that seemed to show—with arresting clarity—a flying saucer floating above the barns and brambles of their farm. The Canadian navy went searching in 1967 for a UFO that a dozen people saw crash into the water near Shag Harbor, a Nova Scotia fishing village. Friedman wrote about Ronnie Johnson, a Kansas teenager who, in 1971, happened upon a brightly lit mushroom-shaped object hovering two feet above the ground on his father's farm. Johnson and his dog were temporarily paralyzed, and as the UFO sped away, it left behind a glowing ring of dirt, which afterward could not absorb water. Soil samples revealed "too high a level of soluble mineral," Friedman says. "I call it salty, because that's what it boils down to." Even years later, nothing would grow on that spot.

As compelling as the first-person accounts were, what spoke to Friedman most clearly was the data. He's always had a numerical mind, a gift he believes he inherited from his grandfather, a fruit and vegetable peddler and Eastern European immigrant who arrived in America with no money or education, but with a formidable internal arithmetic. He was one of those guys, Friedman says, who could write down a string of prices on a paper bag and add them in his head. "No cash register." Two generations later, Friedman pulled so far ahead of the other third graders in math that, by the middle of the school year, his teachers moved him to fourth grade.

Analyzing UFO data, Friedman drew on his nuclear physics expertise. He looked for clues to extraterrestrial propulsion systems in the fission-powered aircraft carriers and an electromagnetic submarine built in the 1960s by a Westinghouse colleague. "It is possible to envision an airborne analog" of that submarine, Friedman writes in an article posted on his website, "in which seawater is replaced by ionized electrically conducting air, and conventional electromagnetic fields are produced by superconducting magnets which need little space, very little power and weight, and generate very high magnetic fields. ... The resulting system would be symmetric, highly maneuverable, relatively silent, often have a glow around it, and be capable of sudden starts and stops."

The other lure of UFOs was, simply, wonder. He remembers looking up at the New Hampshire sky his first night at Young Judea camp and thinking, "'Where did all those stars come from?' You sure didn't see them in Linden, New Jersey." And that's exactly the point, he says: "Just because you can't see it doesn't mean it's not there, which is an important lesson to learn as a researcher." Those same stars had hung over his roof every night back home in New Jersey, but he'd never laid eyes on them. "Who ever saw the Milky Way? Well, in New Hampshire, you could see the Milky Way."

Most people believe in aliens. They may not tell their friends and neighbors, but they tell pollsters. In 1997 a CNN poll found that 80 percent of Americans think the government is hiding information about UFOs, and 64 percent believe that extraterrestrials have contacted humans. In a 2007 Associated Press poll, 14 percent said they'd seen a UFO. These numbers do not surprise Friedman. At the end of his lectures, he often asks the audience how many of them have seen a flying saucer. "And the hands go up," he says, "each one thinking he's the only one. They know I'm not going to laugh, but they're not sure about the other people." Then he starts counting: 1, 2, 3, …, 10, 15, 20, … By the time he's finished, he says, usually ten percent of the audience have their hands raised. In a crowd of 500—not unusual for Friedman—that's 50 people. "But then I ask, 'How many of you reported what you saw?'" Nearly every hand drops. "I've discovered," he says, "that there is this huge body of sightings that you won't run into unless you directly ask, in circumstances where it's OK for people to admit it."

In 40 years, Friedman says, he's had only 11 hecklers—"and two of them were drunk." Before he began lecturing professionally, he organized UFO-themed brown-bag lunches with nuclear physics colleagues. People were more interested than incredulous. "I'm not a masochist," he often says. "I wouldn't do this if people gave me a hard time."

Over a lunch of chardonnay and seafood chowder at a restaurant overlooking the St. John River, Friedman and his friend Roderick Nolan start in on a conversation about ancestors from the old country, which leads to the Irish potato famine and the Holocaust, which leads to the definition of God and the brutality of the human race. "Regardless of where we live in this little speck of dust in the cosmos, we are capable of terrible things,"Nolan muses. Which sends Friedman, as so many topics inexorably do, back to UFOs. "We're a primitive society whose major activity is tribal warfare," he says, echoing a line from his lecture. "People say, 'Why would aliens come here?' I say, 'I think they're here to quarantine us.'" Now he's off and running: "At the end of World War II, there were three signs that soon these Earthling idiots would be moving out into the galaxy: V-2 rockets, atomic bombs, and radar. … And isn't it amazing, the only place in the world where you could check on all three of those technologies is southeastern New Mexico. That's what Roswell was."

Probably more than any other single UFO event, the Roswell incident has dominated Friedman's professional life. He heard about it in 1978, 31 years after a rancher reported finding what he described as tinfoil, paper, pieces of rubber, and kite-sized sticks. He went to the sheriff, who went to the authorities at the Roswell Army air field, who, after first issuing a press release saying that remains of a "flying disc" had been recovered, revised their conclusion. What the rancher, Mack Brazel, had found, they explained, was debris from a high-altitude weather balloon. Newspapers across the country picked up the story, but it faded quickly.

Friedman was in Baton Rouge for a lecture at Louisiana State University when he first heard the details. A TV station manager told him about a buddy from his ham radio days named Jesse Marcel, who lived in nearby Houma. In 1947 Marcel had been the first Army intelligence officer on the scene in Roswell. He'd hiked out to where the debris landed and accompanied it to Wright-Patterson Air Force base. Friedman called Marcel and asked him to share what he remembered from those first few days. After that, the whole story of Roswell started to crack open.

Over the next decade, Friedman and fellow ufologist Bill Moore sought out witness after witness, leapfrogging from one account to another until they had testimony from 62 people, including the rancher's son and neighbors—by then Brazel was long dead—officers from the air base, and the Army public information officer who wrote the first press release about a "flying disc." Friedman found Glenn Dennis, the town mortician, who claimed he got a call from the air field, asking about child-sized caskets. "For the aliens," Friedman explains, whose diminutive bodies would have been thrown from the wreckage. He recalls visiting Dennis in Lincoln, New Mexico, interviewing him amid the celebrations of a Billy the Kid pageant. "I have a tape of him telling me his story, and the mariachi band going in the background." Other ufologists followed Friedman's rediscovery of Ros­well, publishing their own books, uncovering other information. The incident took root in the popular imagination. In 1992 the Roswell UFO museum opened, followed four years later by the annual Roswell UFO Festival.

Friedman's audiences may not give him a hard time, but a ufologist's career isn't without its skirmishes, and over the decades he has taken on his fair share. He wears his triumphs like badges: the Oxford Union debate where he won 60 percent of the vote, the physics professors he silenced when they tried to sandbag him in front of their students. Friedman sells DVDs of his two-hour "formal debate" against astronomer and retired Air Force pilot James McGaha, and he can recount word-for-word the arguments he's had with listeners of call-in shows.

His list of antagonists is long. On it are UFO skeptics and UFO frauds, some of whom he has unmasked. He's disappointed in academic astronomers, who "think they know all there is to know" about interstellar travel, and in reporters who, year after year, fail to examine the "cosmic Watergate" of the government's UFO cover-up. Friedman calls the SETI Institute, which listens for radio signals from outer space, the "silly effort to investigate," because, he says, aliens wouldn't contact us with antique radio technology. He's still vexed with physics classmate Carl Sagan, AB'54, SB'55, SM'56, PhD'60, for refusing to give credence to UFOs. Friedman liked Sagan; the two corresponded, and Friedman visited him a few years before he died. But Sagan's attitude bothers him to this day. "The reliable cases are uninteresting," Sagan wrote of UFO sightings, "and the interesting cases are unreliable." Says Friedman, "That's just totally false."

One spat with skeptic Phil Klass involved a bet over the typography of Truman-era classified memos. It ended with Friedman publishing in his first book a photocopy of the $1,000 check Klass wrote after losing. Later, when Friedman moved to Canada, Klass wrote to the National Research Council in Ottawa to warn them of his arrival and of the "half-truths and falsehoods" in his work. "Like wrestling with an octopus," Klass wrote, "when you manage to pin down one leg, the other seven are still thrashing about."

The "debunkers," as Friedman calls them, growling out each syllable with disdain, have never shaken him with a question he couldn't rebut using the facts and figures in his head or the avalanche of documents in his study. Among the debris is a black-and-white photo taken a couple of years after he went on the road full time. A 36-year-old Friedman stands on a riser behind a tabletop lectern, a microphone at his chin and a projector screen to his left. The hand-drawn sign at his feet reads: "Flying Saucers ARE Real, Stanton Friedman, April 29, 1971, 6:45, Student Lounge." His suit hangs baggy at the knees, and a tie clip holds a striped necktie to his shirt. As he gazes down at his notes, you can see, behind his beard, the hint of a smile. He looks as if he is just about to speak.

"Facts in hand before mouth in gear." That's Friedman's ethos. Of all of the catchphrases he's invented over the years—and there are many—it's the one he tries hardest to live by. In 2001, decades after challenging his fifth-grade teacher on the motion of the solar system, Friedman returned to Linden for his 50th high school reunion. An old friend mentioned that Miss Gutkin still came to synagogue. Friedman's eyes widened. Here was a chance to see her again, to tell her the story that for years he'd been telling everyone else, about how his life was changed that day, how he learned the value of facts in hand—how, all those years ago, he'd been right. "So I went to the temple for old time's sake," he says. He found Mrs. Gutkin, by then in her 80s, and he told her the whole story. She didn't remember him, but that didn't matter. "I needed to tell her," he says, "that she had inspired me to go for the facts. Always to go for the facts."