火星上的暗沙瀑布
(原标题: Dark Sand Cascades on Mars)
2025-06-29
浏览次数: 22
这些树生长在火星上吗？否。火星勘测轨道飞行器在覆盖着轻霜的粉红色沙丘上拍摄到了一组组深棕色的条纹。这张特色照片是2008年4月在火星北极附近拍摄的。那时，随着春天的太阳融化了较轻的二氧化碳冰，火星沙丘内部的深色沙子变得越来越明显。当发生在沙丘顶部附近时，深色的沙子可能会沿着沙丘倾泻而下，在沙丘表面留下深色的条纹——这些条纹最初可能看起来是站在浅色区域前面的树木，但没有投射阴影。直径约25厘米的物体在这张跨度约1公里的图像上被分辨出来。这张照片的某些部分的特写显示，滚滚的羽流表明，即使在拍摄这张照片的时候，沙流也在发生。《天体惊喜》：APOD在你生日那天给你拍了什么照片？(1995后)
查看原文解释
Are these trees growing on Mars? No. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The featured 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. Celestial Surprise: What picture did APOD feature on your birthday? (post 1995)