Clyde Tombaugh

From Wikipedia, the free encyclopedia
Jump to: navigation, search
"Tombaugh" redirects here. For other uses, see Tombaugh (disambiguation).
Clyde Tombaugh
Clyde W. Tombaugh.jpeg
Tombaugh at his family's farm with his homemade telescope (1928)
Born Clyde William Tombaugh
(1906-02-04)February 4, 1906
Streator, Illinois, U.S.
Died January 17, 1997(1997-01-17) (aged 90)
Las Cruces, New Mexico, U.S.
Nationality American
Occupation Astronomer
Known for Discovery of Pluto
Spouse(s) Patricia (1912–2012)
Children Annette and Alden
Relatives Clayton Kershaw (great-nephew)
Matthew Tombaugh
Richard Tombaugh
Awards Jackson-Gwilt Medal (1931)
Rittenhouse Medal (1990)

Clyde William Tombaugh (/ˈtɒmb/; February 4, 1906 – January 17, 1997) was an American astronomer. He discovered Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt. At the time of discovery, Pluto was considered a planet but was later reclassified as a dwarf planet. Tombaugh also discovered many asteroids. He also called for the serious scientific research of unidentified flying objects, or UFOs.

Life and career[edit]

Tombaugh was born in Streator, Illinois, the son of Adella Pearl (Chritton) and Muron Dealvo Tombaugh, a farmer.[1] After his family moved to Burdett, Kansas in 1922, Tombaugh's plans for attending college were frustrated when a hailstorm ruined his family's farm crops.[2] Starting in 1926, he built several telescopes with lenses and mirrors by himself.[2] In order to better test his telescope mirrors, Tombaugh, with just a pick and shovel, dug a pit 24 feet long, 8 feet deep, and 7 feet deep. This cave provided a constant air temperature, free of air currents. It was also used by the family as a root cellar and emergency shelter.[3] He sent drawings of Jupiter and Mars to the Lowell Observatory, which offered him a job.[4] Tombaugh worked there from 1929 to 1945.

Following his discovery of Pluto, Tombaugh earned bachelor's and master's degrees in astronomy from the University of Kansas in 1936 and 1938.[2] During World War II he taught naval personnel navigation at Northern Arizona University.[2] He worked at White Sands Missile Range in the early 1950s, and taught astronomy at New Mexico State University from 1955 until his retirement in 1973.


In August 1992, JPL scientist Robert Staehle called Tombaugh, requesting permission to visit his planet. "I told him he was welcome to it," Tombaugh later remembered, "though he's got to go one long, cold trip."[7] The call eventually led to the launch of the New Horizons space probe to Pluto in 2006.

Following the passage on July 14, 2015 of Pluto by the New Horizons spacecraft the "Cold Heart of Pluto" was named Tombaugh Regio.


Tombaugh died on January 17, 1997, when he was in Las Cruces, New Mexico, at the age of 90. A small portion of his ashes was placed aboard the New Horizons spacecraft. The container includes the inscription: "Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system's 'third zone'. Adelle and Muron's boy, Patricia's husband, Annette and Alden's father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906–1997)".[8]

Tombaugh was survived by his wife, Patricia (1912–2012), and their children, Annette and Alden.[9]




Through the daughter of his youngest brother, Robert M., Tombaugh is the great uncle of Los Angeles Dodgers pitcher Clayton Kershaw.[11]

Discovery of Pluto[edit]

Tombaugh created his photographic plates using this 13-inch astrograph

While a young researcher working for the Lowell Observatory in Flagstaff, Arizona, Tombaugh was given the job to perform a systematic search for a trans-Neptunian planet (also called Planet X), which had been predicted by Percival Lowell and William Pickering.

Tombaugh used the observatory's 13-inch astrograph to take photographs of the same section of sky several nights apart. He then used a blink comparator to compare the different images. When he shifted between the two images, 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, near the place predicted by Lowell, and subsequent observations showed it to have an orbit beyond that of Neptune. This ruled out classification as an asteroid, and they decided this was the ninth planet that Lowell had predicted. The discovery was made on Tuesday, February 18, 1930, using images taken the previous month.[12] The name "Pluto" was suggested by Venetia Burney, then an 11-year-old English schoolgirl, who died in April 2009, having lived to see the reclassification of Pluto as a dwarf planet. It won out over numerous other suggestions because it was the name of the Roman god of the underworld, who was able to render himself invisible, and because Percival Lowell's initials PL formed the first 2 letters. The name Pluto was officially adopted on May 1, 1930.

Following the discovery, starting in the 1990s, of other Kuiper belt objects, Pluto began to be seen not as a planet orbiting alone at 40 AU, but as the largest of a group of icy bodies in that region of space. After it was shown that at least one such body was more massive than Pluto, on August 24, 2006 the International Astronomical Union (IAU) reclassified Pluto, grouping it with two similarly sized "dwarf planets" rather than with the eight "classical planets".

Tombaugh's widow Patricia stated after the IAU's decision that while Clyde may have been disappointed with the change, since he had resisted attempts to remove Pluto's planetary status in his lifetime, he would have accepted the decision now if he were alive. She noted that he "was a scientist. He would understand they had a real problem when they start finding several of these things flying around the place."[13] Hal Levison offered this perspective on Tombaugh's place in history: "Clyde Tombaugh discovered the Kuiper Belt. That's a helluva lot more interesting than the ninth planet."[14]

Further search[edit]

Tombaugh continued searching for some years after the discovery of Pluto, and the lack of further discoveries left him satisfied that no other object of a comparable apparent magnitude existed near the ecliptic. No more trans-Neptunian objects were discovered until (15760) 1992 QB1, in 1992.

However, more recently the relatively bright object Makemake has been discovered. It has a relatively high orbital inclination, but at the time of Tombaugh's discovery of Pluto, Makemake was only a few degrees from the ecliptic near the border of Taurus and Auriga[15] at an apparent magnitude of 16.[16] This position was also very near the galactic equator, making it almost impossible to find such an object within the dense concentration of background stars of the Milky Way. In the fourteen years of looking for planets, Tombaugh looked for motion in 90 million star images.[17]

Asteroids discovered[edit]

Tombaugh compared his photographic plates using this blink comparator.

Tombaugh is officially credited by the Minor Planet Center with discovering 15 asteroids, and he observed nearly 800 asteroids[18] during his search for Pluto and years of follow-up searches looking for another candidate for the postulated Planet X. Tombaugh is also credited with the discovery of periodic comet 274P/Tombaugh–Tenagra.[19] He also discovered hundreds of variable stars, as well as star clusters, galaxy clusters, and a galaxy supercluster.[2]

Asteroids discovered by Tombaugh
Designation Discovery
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 Baltuck November 3, 1929
(6618) 1936 SO September 16, 1936
7101 Haritina October 17, 1930
7150 McKellar October 11, 1929
(8778) 1931 TD3 October 10, 1931

Interest in UFOs[edit]


Tombaugh observed these rectangles of light for about 3 seconds and his wife saw them for about 1 12 seconds. He never supported the interpretation as a spaceship that has often been attributed to him. He considered other possibilities, with a temperature inversion as the most likely cause.[20]










Near-Earth satellite search[edit]





See also[edit]


  1. ^ Tombaugh, Clyde; Patrick Moore (1980). Out of the Darkness: The Planet Pluto. Harrisburg, Pennsylvania: Stackpole Books. p. 17. ISBN 0-8117-1163-3.  "I was born on a farm near Streator, Illinois, on 4 February 1906."
  2. ^ a b c d e f "A Man of Universal Wonder". American Academy of Achievement. 2006-09-09. Retrieved 2010-04-25.  External link in |work= (help)
  4. ^ BBC Sky at Night episode on Clyde Tombaugh
  5. ^ "(1604) Tombaugh". Asteroid Dynamic Site. Retrieved 2007-02-28. 
  8. ^ Buckley, M.; Alan Stern (2006-02-03). "Happy 100th Birthday, Clyde Tombaugh". JHU Applied Physics Laboratory. Retrieved 2009-05-19. 
  11. ^ Berg, Ted (July 30, 2013). "Clayton Kershaw disses International Astronomers Union over Pluto". USA Today. Retrieved August 1, 2013. 
  12. ^ Kansas State Historical Society portrait
  13. ^ Associated Press (2006-08-25). "Pluto Discoverer Saw It Coming, Says His Widow". CTV. Retrieved 2007-02-28. 
  14. ^ Robert Irion (February 5, 2014). "Pluto Wins". Slate. Retrieved February 6, 2014. 
  15. ^ based on Minor Planet Center online Minor Planet Ephemeris Service: March 1, 1930: RA: 05h51m, Dec: +29.0
  16. ^ "HORIZONS Web-Interface". JPL Solar System Dynamics. Retrieved 2008-07-01.  External link in |publisher= (help)
  20. ^ The World of Flying Saucers: A scientific examination of a major myth of the space age, by Donald H. Menzel and Lyle G. Boyd, 1963, Doubleday, pp. 266-70.
  22. ^ Final report of Project Twinkle
  24. ^ Clark, Jerry (1997). UFO Encyclopedia 2. p. 896. 
  32. ^ Los Angeles Times. 1957-09-04.  Missing or empty |title= (help)
  33. ^ David J. Eicher (January 2010). "Astronomy ("Editors dedicate... new observatory")". Kalmbach Publishing: 8. 



External links[edit]