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The Tolstoj quadrangle in the equatorial region of Mercury runs from 144 to 216° longitude and -25 to 25° latitude. It was provisionally called "Tir", but renamed after Leo Tolstoy by the International Astronomical Union in 1976.〔International Astronomical Union, Commission 16, 1977, Physical study of planets and satellites, in Proceedings 16th General Assembly 1976, International Astronomical Union Transactions, v. 16B, p. 325, 331–336, 355–362.〕 Also called Phaethontias. It contains the southern part of Caloris Planitia, which is the largest and best preserved basin seen by Mariner 10. This basin, about 1550 km in diameter, is surrounded by a discontinuous annulus of ejecta deposits of the Caloris Group that are embayed and covered by broad expanses of smooth plains. The southeast half of the quadrangle is dominated by ancient crater deposits, by nondescript rolling to hummocky plains materials between individual craters, and by isolated patches of nondescript plains. The ancient and degraded Tolstoj multiring basin, about 350 km in diameter, is in the south-central part of the quadrangle. The large, well-preserved crater Mozart (285 km diameter) is a prominent feature in the western part of the area; its extensive ejecta blanket and secondary crater field are superposed on the smooth plains surrounding Caloris. Low-albedo features Solitudo Neptunii and Solitudo Helii, adopted from telescopic mapping, appear to be associated with the smooth plains material surrounding Caloris; a third low-albedo feature, Solitudo Maiae, appears to be associated with the Tolstoj Basin.〔For location of albedo features see 〕 Mercury’s rotation period of 58.64 days is in two-thirds resonance with its orbital period of 87.97 days Therefore, at its equator, longitudes 0° and 180° are subsolar points (“hot poles”) near alternate perihelion passage. The “hot pole” at 180° lies within the Tolstoj quadrangle; at perihelion, equatorial temperatures range from about 100 K at local midnight to 700 K at local noon. This daily range of 600 K is greater than that on any other body in the solar system.〔 Mariner 10 photographic coverage was available for only the eastern two-thirds of the Tolstoj quadrangle. Image data from three Mariner 10 encounters with Mercury were used in mapping the quadrangle. ==Stratigraphy== 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「Tolstoj quadrangle」の詳細全文を読む スポンサード リンク
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