Stern, S. Alan Space Science and Engineering Division, Southwest Research Institute, Boulder, Colorado.
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- Early information
- Size and density
- Surface and atmosphere
- Pluto and the Kuiper Belt
- Planetary status
- New Horizons
- Links to Primary Literature
- Additional Readings
A dwarf planet and a member of the Kuiper Belt (a disk of small planets and planetesimals that surrounds the solar system beyond the orbit of Neptune). Pluto (Fig. 1) was discovered on February 18, 1930, by Clyde W. Tombaugh at the Lowell Observatory in Flagstaff, Arizona. Tombaugh discovered Pluto on photographic plates taken with a special astronomical camera as part of a systematic search. Pluto's name was suggested later in 1930 by Venetia Burney, an English schoolgirl. At the time and until 2006, Pluto was considered as the ninth planet of the solar system orbiting around the Sun. However, in 2006, the International Astronomical Union reclassified Pluto as the largest known dwarf planet. The population of dwarf planets far outnumbers the population of large planets, drawing attention to the fact that solar system formation predominantly creates small planets, not large planets, as had been thought. See also: Kuiper Belt; Planet; Solar system; Sun
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