2017年8月24日星期四

A World of Snowy Dunes on Mars


It was spring in the Northern hemisphere when this image was taken on May 21, 2017, by the HiRISE camera on NASA's Mars Reconnaissance Orbiter. Over the winter, snow and ice have inexorably covered the dunes. Unlike on Earth, this snow and ice is carbon dioxide, better known to us as dry ice.

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