Profile: Clyde Tombaugh
Discoverer of Planet Pluto

"Now I had figured out beforehand, if there was a Planet X, how I would recognize it if I encountered it."

When Clyde Tombaugh entered the University of Kansas, he tried to register for freshman astronomy. The professor in charge of the course refused to enroll him. He thought Tombaugh's presence in the class would be inappropriate, since Tombaugh had already achieved something only a handful of astronomers have ever done. As a 24-year-old research assistant at the Lowell Observatory in Flagstaff, Arizona, without the benefit of any formal training in astronomy, Tombaugh had discovered a new planet: Pluto.

Clyde Tombaugh's interest in astronomy began when he was a young boy, growing up on a farm in the Middle West, without access to observatories, universities or even a large library. Unable to afford a college education, Tombaugh taught himself solid geometry and trigonometry, and studied the stars through telescopes he built himself.

After his discovery of Pluto won him world renown, Tombaugh at last acquired the college education he had long desired. He resumed astronomical research for the Lowell Observatory, taught navigation to the U.S. military during World War II, and after the war, used his expertise in optics to assist the military in the development of missiles at White Sands Missile Range.

Long into his retirement, Clyde Tombaugh continued to enjoy stargazing from the telescopes in his own backyard. Although the discovery of more objects in the Kuiper Belt beyond Neptune has caused astronomers to reconsider the formal definition of a planet, the significance of Tombaugh's discovery has grown with the years. Clyde Tombaugh discovered much more than a single planet -- he opened a door to the outer reaches of our solar system.