Clyde W. Tombaugh

Clyde W. Tombaugh

Discovered the dwarf planet Pluto, hundreds of variable stars and asteroids, and two comets.

Clyde William Tombaugh was born in Streator, Illinois on February 4, 1906. He grew up on the family farm there until 1922 when the Tombaughs moved to a farm northwest of Burdett, Kansas. Clyde developed an early love of astronomy after an uncle loaned him a telescope. A graduate of Burdett High School in 1925, he was financially unable to attend college. Tombaugh pursued his interest in astronomy, and in 1926, built his first homemade telescope. He built two more telescopes in the next two years, mastering optics, grinding his own lenses and mirrors, and further honing his observational skills.

Using these homemade telescopes, Tombaugh made drawings of the planets Mars and Jupiter and sent them to the Lowell Observatory in Flagstaff, Arizona. The staff there was impressed by his work, and in 1929, Tombaugh was hired to conduct planet-search photography at Lowell, specifically the attempt to find what was called “Planet-X,” thought to be on the fringes of the solar system. On February 18, 1930, Clyde Tombaugh earned a permanent place in history when he discovered what was then acclaimed as the ninth planet, which was officially named Pluto on May 1, 1930. Smaller than Mercury and billions of miles from the Sun, the discovery of Pluto with the technology of the time is an enduring testament to Tombaugh’s dedication and eye for detail. He was awarded the Jackson-Gwilt Medal and Gift by the Royal Astronomical Society in recognition of his discovery, as well as a scholarship to the University of Kansas.

In 1932, Tombaugh enrolled there, earning a Bachelor of Science degree four years later. He continued to work at Lowell Observatory during the summers, and after graduation, returned to Flagstaff to work full-time. He soon returned to college, and in 1939, received his master’s degree, also from the University of Kansas.

During his fourteen years at the Lowell Observatory, Clyde Tombaugh discovered hundreds of variable stars and asteroids and two comets. While engaged in the search that yielded Pluto, he also found many previously unknown star clusters, clusters of galaxies, and a nova. He mapped the Great Perseus-Andromeda Stratum of Extra-Galactic Nebulae, one of over 29,000 galaxies he documented. Dr. Tombaugh remained at the observatory until 1943, then taught navigation for the Navy at Arizona State College (now Northern Arizona University) in Flagstaff until the end of the Second World War in 1945.

As the Lowell Observatory did not have the financial resources to rehire him after the war, Tombaugh became a Visiting Assistant Professor in Astronomy at the University of California at Los Angeles until 1946, when he transferred to the ballistics research laboratories at the White Sands Proving Ground (now White Sands Missile Range, or WSMR) New Mexico. As Chief of the Optical Measurements Section there, he developed tracking telescopes used to photograph rockets and missiles during the test flight. Dr. Tombaugh also directed optical and photographic research in the Systems Engineering Branch at White Sands. He designed many new instruments there, among them, in 1951, a camera called the IGOR (Intercept Ground Optical Recorder), which remained in use at White Sands for the next thirty years.

After nine years at White Sands, Tombaugh left in 1955. He later received the medal of the Pioneers of White Sands Missile Range for his work there. From 1953 to 1955, he also led the Near Earth Satellite Search, an Army project conducted by the Lowell Observatory. This search was crucial in identifying any small natural satellites of the Earth as a preparatory step to beginning space exploration. This project was transferred from White Sands Proving Ground to the Physical Science Laboratory at New Mexico State University (NMSU) when Tombaugh took a position there in 1955. Fours year later, Tombaugh’s group released the Near Earth Satellite Search final report. As no natural satellites had been found by the survey, NASA had some assurance that rockets, and eventually humans, could be sent into space without colliding with natural orbiting debris.

From 1955 until his retirement in 1973, Clyde Tombaugh was on the faculty at New Mexico State University. From 1958 to 1973, he directed the NMSU photographic Planetary Patrol of Mercury, Venus, Mars, Jupiter, and Saturn. In addition to that project, until 1968, Dr. Tombaugh also conducted research such as studying the geology of Mars and helping chose a location for an Air Force observatory near Cloudcroft, New Mexico.

By the time Clyde Tombaugh retired, he and his Planetary Patrol researchers had confirmed the daily rotation period of Mercury, determined the vortex nature of Jupiter’s Great Red Spot, and developed a new photographic technique for the small Earth satellites search. Reflecting on his career late in his life, Tombaugh often said: “I’ve really had a tour of the heavens.”

In 1972, the Clyde W. Tombaugh Observatory on the New Mexico State University campus was dedicated. Out of the Darkness, The Planet Pluto, an autobiographical account of his greatest discovery was published with co-author Patrick Moore in 1980. The same year the Clyde W. Tombaugh IMAX Theater and Planetarium opened in Alamogordo, New Mexico. In 1986, the Clyde Tombaugh Scholars Fund in support of postdoctoral fellowship at New Mexico State University was established.

Dr. Tombaugh conducted astronomical research long after his 1973 retirement. When the Smithsonian Institute asked if it could exhibit the nine-inch telescope he constructed in 1928 with which he made the drawings that impressed the Lowell Observatory staff, he told them he was still using it. Until shortly before his death, Tombaugh used that telescope, built with parts of discarded farm machinery and a shaft from his father’s 1910 Buick, to make observations from his back yard in Mesilla Park, near Las Cruces.

On January 17, 1997, Clyde W. Tombaugh died at his home at the age of ninety-one. After he was cremated some of his ashes were placed aboard the New Horizons probe, which was launched on January 19, 2006, and scheduled to reach Pluto in 2015. Asteroid 1604 Tombaugh is named in his honor.

With recent advances in telescopes, a host of objects have been discovered circling the sun in the “Kuiper Belt,” an area extending billions of miles into the outer reaches of the solar system beyond the planet Neptune. One “Kuiper Belt Object” (KBO) called Eris is actually larger than Pluto. Several other “KBOs” (also called minor planets) are only slightly smaller than Pluto. Thousands more such objects may be found by the New Horizons probe after it leaves Pluto for the outer reaches of the Kuiper Belt. The existence of Eris and other minor planets similar to Pluto led the International Astronomical Union to officially re-classify Pluto as a Minor Planet on August 24, 2006.