A new giant in the Kuiper belt.When it comes to the biggest bodies in the solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. The principal members of the sun's retinue are the eight major planets; other parts of the solar system are discussed in separate articles: see comet, asteroid, and meteor. beyond Neptune, Pluto Pluto, in astronomyPluto, in astronomy, a dwarf planet and the first Kuiper belt, or transneptunian, object (see comet) to be discovered (1930) by astronomers. Pluto has an elliptical orbit usually lying beyond that of Neptune. Although Pluto was long regarded as a planet, since the discovery (beginning in 1992) of other Kuiper belt objects, including one with a diameter larger than that of Pluto, astronomers have recognized the need to reclassify Pluto, tops the list. CharonCharon, in astronomyCharon, in astronomy, the natural satellite, or moon, of Pluto.Charon, in mythologyCharon, in Greek mythology: see Hades., Pluto's moon, has always been designated the runner-up.Astronomers now have for the first time found an object that's slightly bigger than Charon. It's an icy body in the Kuiper belt Kuiper belt: see comet; Kuiper, Gerard Peter., a reservoir of comets in the outer solar system. Dubbed 2001 KX76, this object has an estimated diameter of 1,270 kilometers, making it the largest known member of the belt. Charon, in comparison, has a diameter of about 1,200 km, and Pluto is 3,300 km across. The newly discovered object lies an estimated 43 astronomical units astronomical unit (AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e.g., Mercury is just over 1-3 AU and Pluto is about 39 AU from the sun. from the sun--43 times the Earth-sun distance--and appears to have the largest intrinsic brightness of any Kuiper belt resident, researchers report in a July 5 circular of the International Astronomical Union. The find usurps the title of Kuiper belt king from another recently discovered resident, 20000 Varuna Varuna (vûr`  nə): see Veda., which measures 900 km across. Some astronomers argue, however, that Pluto is the true behemoth behemoth (bē`hĭmŏth, bĭhē`–) [Heb.,=plural of beast], large, fanciful primeval monster, like Leviathan, evoking the hippopotamus mentioned in the Book of Job. In the Book of Psalms the term occurs in a non-mythological context. of the belt, rather than the pipsqueak of planets (SN: 6/9/01, p. 360). Robert L. Millis, director of the Lowell Observatory Lowell Observatory, astronomical observatory located in Flagstaff, Ariz.; it was founded in 1894 by Percival Lowell, the American astronomer who popularized the idea that Mars might support intelligent life. Its original telescope, still in operation, is a 24-in. (61-cm) refractor; also located at the Mars Hill site are the 13-in. (33-cm) A. Lawrence Lowell photographic camera used by Clyde Tombaugh when he discovered Pluto, and a 16-in. in Flagstaff, Ariz., and his colleagues discovered 2001 KX76 in images from a survey of the Kuiper belt taken by a 4-meter telescope at Cerro Tololo Inter-American Observatory in La Serena La Serena (lä sārā`nä), city (1990 est. pop. 105,600), capital of Coquimbo region, N central Chile, on the Elqui River. A commercial and agricultural center in a region of orchards and vineyards, it is a popular resort., Chile. "Until the Kuiper belt has been thoroughly explored, we cannot pretend to know the extent or the content of the solar system," says Millis. "We have every reason to believe that objects ranging up to planets as large or larger than Pluto are out there [in the Kuiper belt] waiting to be found." |
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