NASAのインスタグラム(nasa) - 2月11日 07時14分

Sand dunes...on Mars! ? With an elongated crescent form, these "barchan dunes" are located near Nili Patera and are formed by the continuous action of the wind blowing in the same direction.
The orientation of these dunes tells us that the prevailing wind blows from right to left (east to west). The wind is continuously moving sand grains up the longer dune slope, towards the top. The small ripples on the slope are caused by this movement. When the sand grains arrive at the top, they fall down the steeper and shorter slope, which as a consequence, has no ripples. It is this gradual sand movement that causes the dunes to slowly move over time.

Image Credit: NASA/JPL-Caltech/University of Arizona
#mars #geology #texture #landforms #nasa #picoftheday #redplanet #solarsystem #astronomy #science #space

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