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原文:
They might look like trees on Mars, but they’re not. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The above image was taken in 2008 April near the North Pole of Mars. At that time, dark sand on the interior of Martian sand dunes became more and more visible as the spring Sun melted the lighter carbon dioxide ice. When occurring near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks — streaks that might appear at first to be trees standing in front of the lighter regions, but cast no shadows. Objects about 25 centimeters across are resolved on this image spanning about one kilometer. Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring even while the image was being taken.
中文翻譯:
在火星上，看似樹木的物體其實並不是真正的樹。在火星探測器「Mars Reconnaissance Orbiter」拍攝的照片中，我們可以看到一些暗褐色的條紋，這些條紋出現在被輕微霜凍覆蓋的粉紅色沙丘上。上述圖片是在2008年4月於火星北極附近拍攝的。那時，隨著春季陽光融化輕質的二氧化碳冰，沙丘的內部暗沙越來越顯露出來。
當這些暗沙出現在沙丘的頂部時，可能會沿著沙丘下滑，形成暗色的表面條紋。這些條紋初看時可能像是樹木伫立在較亮的區域前方，但實際上並不會投射任何陰影。這張圖片解析度約能捕捉到25厘米大小的物體，並且範圍達到一公里。圖片的特寫顯示有沙塵翻騰的雲朵，顯示在拍攝期間沙石滑動的過程仍在進行中。
#火星探索 #MarsReconnaissanceOrbiter #沙丘現象 #火星 #科學探索 #宇宙奧秘 #太空影像 #自然奇觀 #天文學
來源:NASA每日圖片
