Meet the Man Who Discovered Pluto

Mission Pluto, which airs on tonight at 9/8c on the National Geographic Channel, tells the story of NASA’s New Horizons spacecraft, which is about to culminate a nine-and-half-year, three billion-mile journey by transmitting the first close-up photos of the dwarf planet’s surface.

In addition to its unprecedented scientific mission, New Horizons has an honorary function as well. The spacecraft carries inside it a two-inch aluminum urn, containing some of the ashes of an astronomer named Clyde W. Tombaugh, who’ll finally get within a few thousand miles of the distant world that he discovered back in 1930.

Clyde Tombaugh
Clyde Tombaugh

Tombaugh, who was born in 1906 and died in 1997, has one of the most remarkable stories in the history of science. He was just 24 years old and hadn’t yet even taken a college course when he made his amazing find, while working as an assistant at the Lowell Observatory in Flagstaff, Ariz.

Tombaugh grew up on a farm in Kansas and was interested in astronomy from an early age. As a boy, he peered in the heavens with three-inch telescope that his uncle owned, observing the rings of Saturn, Jupiter’s moons, and the craters of our own Moon, as he recalled in a 1991 interview. His parents indulged his fascination by getting astronomy books for him from the local library and by allowing him to stay up late at night to make his own amateur observations. As a teenager, he read an article in Popular Astronomy magazine by an astronomer named Latimer Wilson, and marveled at the latter’s vivid drawings of Jupiter, which he’d made with the help of an 11-inch refractor telescope that he constructed himself. “Boy, that just sent me!” Tombaugh recalled in the interview. “I had to write him and say, how do you make a telescope like that? So I wrote to him and he responded. That’s how I got started making telescopes.”

Tombaugh taught himself solid geometry and trigonometry “for the fun of it,” and planned to study astronomy in college after graduating from high school. But when a hailstorm ruined his family’s crops, he was forced to postpone his plans. Instead, he made observations in his backyard, using a nine-inch telescope that he built himself, and shivered in the cold Kansas night as he made painstakingly detailed pencil sketches of Mars and Jupiter. His untutored drawings were so good that when he sent them to the Lowell Observatory on a lark, they offered him a job.

The new employee was assigned the astronomy equivalent of grunt work—using the telescope to take wide-angle pictures of the sky at night in rapid succession, developing the plates and putting them on a special machine called the Blink-Comparator to look for evidence of moving objects. It was part of the search for a yet-unseen Planet X whose existence had been predicted by astronomers as far back as the 1840s, based upon irregularities in the orbits of Uranus and Neptune that seemed to be caused by gravity from the planet. The late Percival Lowell, who’d founded the observatory back in 1894, had dubbed it “Planet X,” but when he died in 1916, he still hadn’t located it.

It was tedious and difficult, but Tombaugh decided to stick with it. “I didn’t want to go back to the farm and pitch hay,” he recalled. According to science historians Heather Couper and Nigel Henbest, when his study of the area suggested by his supervisor didn’t yield any results, Tombaugh took it upon himself to expand the search.

His persistence paid off. On Feb. 18, 1930, at around 4 p.m., he was staring at a plate that he’d shot he previous month, when he spotted something that didn’t look like a star. He compared it to another plate, and saw that the object was in a slightly different place. “Instantly, I knew I had a planet beyond the orbit of Neptune because I knew the amount of shift was what fitted the situation,” he recalled. “…I realized in a few seconds that I’d made a great discovery. It was an intense thrill.”

Tombaugh had spotted something that his superiors, one of whom had even scrutinized that same spot in the sky a year before, had missed. When word of his discovery got out, the autodidactic farmboy-turned-astronomer was profiled on the front page of the New York Times. (“I guess I’ll just keep on taking pictures of stars,” he earnestly told the newspaper. “That is what I like to do.”)

Tombaugh, who eventually did earn a masters degree in astronomy from the University of Kansas, went on to an impressive career, in which he discovered hundreds of stars and asteroids and two comets, and documented over 29,000 galaxies. In the 1950s, he led the Near Earth Satellite Search, a project to search for small natural satellites close to our planet. When his group released a report in 1959 verifying that there were no such objects to endanger spacecraft, NASA could proceed ahead with the space program.

The discoverer of Pluto has another intriguing distinction. He was one of the first professional astronomers to report seeing a UFO. In August 1949, while in his backyard in Las Cruces, N.M., he observed what he later described in a letter to a civilian UFO research group as “a geometrical group of faint bluish-green rectangles of light,” which he compared to the famous Lubbock Lights.

Tonight, National Geographic Channel joins top scientists at the Johns Hopkins Applied Physics Laboratory in conjunction with NASA on a historic mission to the edge of our solar system with the goal of capturing the first clear images and data ever recorded of Pluto.

Mission Pluto premieres Tuesday, July 14, at 9/8c on the National Geographic Channel.