2017年10月05日: 冥王星的刀片状原野-（Pluto's Bladed Terrain）--原图下载
Image Credit: NASA,Johns Hopkins Univ./APL,Southwest Research Institute
说明: 这幅摄于新视野号太空船2015年7月飞越的影像，呈现了遥远冥王星刀片状原野的特写。这片具有奇特纹理的锯齿状原野，非常接近冥王星的赤道，主要是由大小和摩天大楼相近的甲烷冰所构成。这些投射出暗影的高耸刀锋状山脊，看来是因昇华而形成的。在冥王星较温暖的地质年代里，经由这种过程中，凝结的甲烷冰并没有溶化成液体，而是直接变成甲烷气体。在地球的安地斯山高原上，昇华的过程造就了许多直竖的刀片状冰层；这种名为扁尖冰柱(penitentes)的刀片状结构，是由水冰所构成，高度至多只有数米。
原文：
Image Credit: NASA,Johns Hopkins Univ./APL,Southwest Research Institute
Explanation: Imagedduring the New Horizons spacecraft flyby in July 2015, Pluto'sbladed terrain is captured in this close-up of the distant world.The bizarre texturebelongs to fields of skyscraper-sized, jagged landformsmade almost entirely of methane ice, found at extreme altitudesnear Pluto's equator.Casting dramatic shadows,the tall, knife-like ridges seem to havebeen formed by sublimation.By that process, condensed methane ice turns directly to methane gaswithout passing through a liquid phaseduring Pluto's warmer geological periods.On planet Earth, sublimation can also produce standing fields of knife-likeice sheets, found along the high plateau of the Andes mountain range.Known as penitentes,those bladed structures are made of water ice and at most a few meters tall.
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