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Astronomy picture of the day - 01-03-2015 - Layered Rocks near Mount Sharp on Mars

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Layered Rocks near Mount Sharp on Mars 
Image Credit: NASAJPL-CaltechMSSS
Explanation: What caused these Martian rocks to be layered? The leading hypothesis is an ancient Martian lake that kept evaporating and refilling over 10 million years -- but has now remained dry and empty of water for billions of years. The featured image, taken last November by the robotic Curiosity rover, shows one-meter wide Whale Rock which is part of the Pahrump Hills outcrop at the base of Mount Sharp. Also evident in the image is cross-bedding -- rock with angled layers -- which were likely facilitated by waves of sandCuriosity continues to find many layered rocks like this as it continues to roll around and up 5.5-km high Mount Sharp.

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