rjxie 发表于 2003-12-31 14:37

[酷图] 火星上一个沙尘暴形成的环形山。

A Dust Devil Crater on Mars
Credit: Malin Space Science Systems, MGS, JPL, NASA
Explanation: What caused the streaks in this Martian crater? Since the above image shows streaks occurring both inside and outside the crater, they were surely created after the crater-causing impact. Newly formed trails like these presented researchers with a tantalizing martian mystery but have now been identified as likely the work of miniature wind vortices known to occur on the red planet - martian dust devils. Another example of wind processes on an active Mars, dust devils had been detected passing near the Viking and Mars Pathfinder landers. Such spinning columns of rising air heated by the warm surface are common in dry and desert areas on planet Earth. Typically lasting only a few minutes, they becoming visible as they pick up loose dust. On Mars, dust devils can be up to 8 kilometers high and leave dark trails as they disturb the bright, reflective surface dust.

ak49 发表于 2003-12-31 20:12

沙尘暴能刮出环形山来。。。。啧啧。。。。。

CooledCoffee 发表于 2004-1-1 01:47

LAMOST 发表于 2004-1-1 20:28

大家可以参看《科学与生活》2004.1期。

ak49 发表于 2004-1-11 16:00

　　这幅火星地表照片是火星全球探测器在2003年9月拍摄的，从照片上可以清晰地看到一个巨大陨石坑，陨石坑是火星与某一个小行星撞击后留下的痕迹。陨石坑直径约为2500米，其坐标为南纬57.4°和西经234°。此外，从照片上还可以看到大量弯曲的黑条纹，这是“尘魔”留下的踪迹，“尘魔”是指火星上发生的类似龙卷风的大气现象。
　　“尘魔”在火星地表上空狂舞，去除了火星地表上层薄薄的尘埃层结构，留下了这样的黑条纹，这一现象反映了火星春季的特征。有意思的是，到2005年开始的春季，这些黑条纹会全部消失，随后又会重新出现。
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