Tombaugh was born in Streator, La Salle County, Illinois. After his family moved to Burdett, Kansas, Tombaugh built his first telescope and sent drawings of his observations of Jupiter and Mars to the Lowell Observatory. These resulted in a job offer. Tombaugh was employed at the Lowell Observatory from 1929 to 1945. Following his discovery of Pluto, Tombaugh earned astronomy degrees from the University of Kansas and Northern Arizona University. He taught astronomy at New Mexico State University from 1955 until his retirement.
The asteroid 1604 Tombaugh 1, discovered in 1931, is named after him. He himself discovered 14 asteroids, beginning with 2839 Annette in 1929, mostly as a by-product of his search for Pluto and his further searches for other planets. The Royal Astronomical Society awarded him the Jackson-Gwilt Medal in 1931.
Discovery of Pluto
While a young researcher working for Lowell Observatory in Flagstaff, Arizona, Tombaugh found Pluto during a systematic search for a trans-Neptunian planet (also called Planet X), which had been predicted by Percival Lowell and William Pickering.
Tombaugh's discovery involved painstaking use of a blink comparator — a device which allows someone to compare two similar photographs by placing them in the viewer's field of vision, and then letting the user switch back and forth — blink — between the two. Tombaugh used the blink comparator to compare photographs of sections of sky taken several nights apart. A moving object, such as a planet, would appear to jump from one position to another while the more distant objects, such as stars, would appear stationary. Tombaugh noticed such a moving object in his search, and subsequent observations showed it to be the planet we call Pluto. The discovery was made on February 18, 1930, using images taken in January of the same year.
The name "Pluto" was suggested by Venetia Burney, an 11-year-old English school girl who is still alive and living in England. It won out over numerous other suggestions partly because it was named after the Roman god of the underworld, who was able to render himself invisible, and partly because Percival Lowell's initials PL formed the first 2 letters. The name Pluto was officially adopted on 1 May 1930.
Tombaugh discovered a total of 14 asteroids, during his search for Pluto and years of follow-up searches looking for another candidate for the postulated Planet X. No more Trans-Neptunian objects were discovered until Template:Mpl, in 1992.
|2839 Annette||October 5, 1929|
|2941 Alden||December 24, 1930|
|3310 Patsy||October 9, 1931|
|3583 Burdett||October 5, 1929|
|3754 Kathleen||March 16, 1931|
|3775 Ellenbeth||October 6, 1931|
|3824 Brendalee||October 5, 1929|
|4510 Shawna||December 13, 1930|
|4755 Nicky||October 6, 1931|
|(5701) 1929 VS||October 26, 1929|
|(6618) 1936 SO||September 16, 1936|
|(7101) 1930 UX||October 17, 1930|
|Template:Mpl||October 11, 1929|
|Template:Mpl||October 10, 1931|
Interest in UFOs
Tombaugh was probably the most eminent astronomer to have reported seeing Unidentified Flying Objects. On August 20, 1949, Tombaugh saw several UFOs near Las Cruces, New Mexico. He described them as six to eight rectangular lights, stating "I doubt that the phenomenon was any terrestrial reflection, because... nothing of the kind has ever appeared before or since... I was so unprepared for such a strange sight that I was really petrified with astonishment." A similar shocked response has been reported by many other who claim to have seen mysterious aerial objects.
Tombaugh was also later to report having seen three of the mysterious Green Fireballs, which suddenly appeared over New Mexico in late 1948 and continued at least through the early 1950s. In 1956 Tombaugh had the following to say about his various sightings:
"I have seen three objects in the last seven years which defied any explanation of known phenomenon, such as Venus, atmospheric optic, meteors or planes. I am a professional, highly skilled, professional astronomer. In addition I have seen three green fireballs which were unusual in behavior from normal green fireballs...I think that several reputable scientists are being unscientific in refusing to entertain the possibility of extraterrestrial origin and nature." 
In 1949, Tombaugh had also told the Naval missile director at White Sands Missile Range, Commander Robert McLaughlin, that he had seen a bright flash on Mars in August 1941, which he now attributed to an atomic blast (mentioned May 12, 1949, in a letter from McLaughlin to Dr. James van Allen).  Tombaugh also noted that the first atomic bomb tested in New Mexico would have lit up the dark side of the Earth like a neon sign and that Mars was coincidentally quite close at the time, the implication apparently being that the atomic test would have been visible from Mars.
In June 1952, Dr. J. Allen Hynek, an astronomer acting as a scientific consultant to the Air Force's Project Blue Book UFO study, secretly conducted a survey of fellow astronomers on UFO sightings and attitudes while attending an astronomy convention. Tombaugh and four other astronomers told Hynek about their sightings, including Dr. Lincoln La Paz of the University of New Mexico. Tombaugh also told Hynek that his telescopes were at the Air Force's disposal for taking photos of UFOs, if he was properly alerted. (Steiger, 268 - 285)
Near-Earth satellite search
Tombaugh's offer may have led to his involvement in a search for near-Earth satellites, first announced in late 1953 and sponsored by the Army Office of Ordnance Research. Another public statement was made on the search in March 1954 (photo at right), emphasizing the rationale that such an orbiting object would serve as a natural space station. (articles) However, according to Donald Keyhoe, later director of the National Investigations Committee on Aerial Phenomena (NICAP), the real reason for the sudden search was because two near-Earth orbiting objects had been picked up on new long-range radar in the summer of 1953, according to a Pentagon source of his.
By May 1954, Keyhoe was making public statements that his sources told him the search had indeed been successful, and either one or two objects had been found. (articles) However, the story didn't really break until August 23, 1954, when Aviation Week magazine stated that two satellites had been found only 400 and 600 miles out. They were termed "natural satellites" and implied that they had been recently captured, despite this being a virtual impossibility. The next day, the story was in many major newspapers. Dr. La Paz was implicated in the discovery in addition to Tombaugh. La Paz had earlier conducted secret investigations on behalf of the Air Force on the Green Fireballs and other unidentified aerial phenomena over New Mexico.
La Paz vehemently denied his involvement in the search, although the New York Times reported on August 29 that a source close to the project said that the story was true and La Paz was indeed involved, in fact had been the one to spot and identify the objects as natural rather than artificial satellites. The same source denied the search had anything to do with flying saucers. (N.Y. Times articles)
However, both La Paz and Tombaugh were to issue public denials that anything had been found. E.g., the May 1955 issue of Popular Mechanics magazine reported: "Professor Tombaugh is closemouthed about his results. He won't say whether or not any small natural satellites have been discovered. He does say, however, that newspaper reports of 18 months ago announcing the discovery of natural satellites at 400 and 600 miles out are not correct. He adds that there is no connection between the search program and the reports of so-called flying saucers." (Popular Mechanics article with photo)
In 1959 Tombaugh was to issue a final report stating that nothing had been found in his search.
- Many biographical articles on Clyde Tombaugh
- Quote from Tombaugh on UFOs
- UFO activities of Tombaugh
- Academic paper on Tombaugh's UFO activities and near-earth satellite search
- Brad Steiger, Project Blue Book, 1976, Ballantine Books, ISBN 0-345-34525-8 (Has Dr. J. Allen Hynek's 1952 letter to Project Blue Book about his astronomer UFO survey and Tombaugh's offer to assist the Air Force in photographing UFOs)
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