He spent 7,000 hours searching the skies for Planet X—but in vain
After a half century, Clyde Tombaugh remembers the moment perfectly. For nine months he had been taking photographs through the new 13-inch telescope at Lowell Observatory in Arizona, then meticulously studying them for evidence of a ninth planet in the solar system. It had long been theorized but never found. Then, about 4 p.m. on Feb. 18, 1930, he found a telltale spot on a series of glass plates. “I knew in an instant,” he recalls. “I thought, ‘That’s it!’ For about 45 minutes, I was the only man in the world with that knowledge.”
Tombaugh—then a 24-year-old farm boy with no college education—told his observatory superiors. After checking his research, they announced the discovery of a planet 3.66 billion miles from the sun. It was named Pluto after the Greek god of the underworld, who was about the only top-ranking Greco-Roman deity left by then. No planet had been located since Neptune in 1846. None has been found since. Tombaugh is the only American ever to discover a planet.
“Hell,” he says now, “all it took was a good telescope and a lot of patience.” The story in fact reads like Horatio Alger in the observatory. Tombaugh was 14 when his father, a farmer in Streator, Ill., bought him a 2½-inch Sears, Roebuck telescope. By the time the family moved to a 1,000-acre wheat farm near Burdett, Kans. two years later, Tombaugh had built a nine-inch, 400-power telescope using an article in Scientific American as a blueprint. He made drawings of Mars and Jupiter and on impulse sent them to Lowell Observatory in Flagstaff in 1928.
A passionate astronomer, Percival Lowell had searched until his death in 1916 for another planet he was sure existed beyond Uranus. His successors took over the search and were so impressed with young Tombaugh they offered him a tryout. “I couldn’t fail,” he remembers. “I only had enough money for one-way train fare.”
Hired at $90 a month, Tombaugh got access to Lowell’s new telescope though his only formal training was one high school physics course. He often worked 15 hours a day, shooting and examining photographs. (Pictures of a patch of sky taken two nights apart reveal movement in close objects such as planets, while vastly more distant stars appear stationary.)
“I’d damn near frozen my fingers on the telescope, it was so cold,” Tombaugh says. “Lowell Observatory is 7,000 feet high, and you couldn’t have any heat or it would disturb the pictures. You are hunched over the telescope till 3 a.m. You could easily go nuts. The observatory knew no professional astronomer would go through that, so they wanted an enthusiastic amateur. With me, they got one.”
His first several weeks were wasted because he spoiled all the pictures. “I couldn’t tell anybody,” he says. Once he made his discovery, though, “All hell broke loose. I got invited to parties, and people would come up and joke how they loved Pluto—and all the other Disney characters—but I didn’t mind.”
The planet he found was not the one Lowell envisioned, which would be much larger than Pluto, itself smaller than the earth’s moon. Tombaugh continued to search photographs for Lowell’s “Planet X” for an estimated 7,000 hours before giving up.
He stayed at the observatory for 13 years, with time off for a B.A. and M.A. at the University of Kansas. He then taught in a Navy navigation program during World War II and later supervised a tracking system at White Sands missile base. In 1955 he went to New Mexico State in Las Cruces as a research director and professor, where he has built one of the nation’s finest departments of astronomy.
At 74, Tombaugh is emeritus, and an observatory at NMSU and an asteroid have been named after him. A consultant to NASA’s Mariner missions to Mars, he says the “birds” in the government who failed to plan a Pluto project for 1989—when it will be closer to earth than it has been for 200 years—”don’t know anything.” Tombaugh still teaches, advises on research and studies the skies. “His only hobby,” smiles his wife, Patsy, “is grinding telescope mirrors.”