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In planetary nomenclature, a tholus (pl. ''tholi'') is a small domical mountain or hill.〔〔 The word is from the Greek θόλος, ''tholos'' (pl. ''tholoi''),〔 which means a circular building with a conical or vaulted roof.〔 The Romans transliterated the word into the Latin ''tholus,'' which means cupola or dome.〔Simpson, D.P. (1968). ''Cassell's New Latin Dictionary;'' Funk & Wagnalls: New York, p. 604.〕 In 1973, the International Astronomical Union (IAU) adopted ''tholus'' as one of a number of official descriptor terms for topographic features on Mars and other planets and satellites.〔〔Greeley, R. (1994) ''Planetary Landscapes,'' 2nd ed.; Chapman & Hall: New York, pp. 35-36.〕 One justification for using neutral Latin or Greek descriptors was that it allowed features to be named and described before their geology or geomorphology could be determined.〔Russell, J.F.; Snyder, C.W.; Kieffer, H.H. (1992). (Origin and Use of Martian Nomenclature ) in ''Mars,'' H.H. Kieffer et al., Eds.; University of Arizona Press: Tucson, AZ, p. 1310.〕 For example, many tholi appear to be volcanic in origin, but the term does not imply a specific geologic origin.〔Russell, J.F.; Snyder, C.W.; Kieffer, H.H. (1992). (Origin and Use of Martian Nomenclature ) in ''Mars,'' H.H. Kieffer et al., Eds.; University of Arizona Press: Tucson, AZ, p. 1312.〕 Currently (March 2015), the IAU recognizes 56 descriptor terms.〔 (See Planetary nomenclature.) Tholi are present on Venus, Mars, asteroid 4 Vesta and on Jupiter's moon Io. File:Tharsis Quadrangle map-la.svg|Map of the Tharsis quadrangle showing major features, several of which are tholi. Tharsis contains many volcanoes, including Olympus Mons, the tallest known volcano in the solar system. File:Ceraunius & Uranius tholi.jpg|''2001 Mars Odyssey'' THEMIS mosaic of Ceraunius Tholus (lower volcano) and Uranius Tholus (upper volcano). Ceraunius Tholus is about as high as Earth's Mount Everest. File:Jovis Tholus.jpg|Western part of Jovis Tholus, as seen by THEMIS on Mars Odyssey spacecraft. Jovis Tholus is in the Tharsis quadrangle. ==Examples of tholi== * Hecates Tholus * Tharsis Tholus 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tholus」の詳細全文を読む スポンサード リンク
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