Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2023 May 2
A view of Mars from the Curiosity rover on Mars 
is pictured in black and white. Many rocks and hills are 
visible, with a hill containing many unusually flat rocks 
visible on the right.
Please see the explanation for more detailed information.

Flat Rock Hills on Mars
Image Credit & Copyright: NASA, JPL-Caltech, MSSS; Processing: Neville Thompson

Explanation: Why are there so many flat rocks on Mars? Some views of plains and hills on Mars show many rocks that are unusually flat when compared to rocks on Earth. One reason for this is a process that is common to both Mars and Earth: erosion. The carbon-dioxide wind on Mars can act like sandpaper when it blows around gritty Martian sand. This sand can create differential erosion, smoothing over some rocks, while wearing down the tops of other long-exposed stones. The featured image capturing several hills covered with flat-topped rocks was taken last month by NASA's Curiosity Rover on Mars. This robotic rover has now been rolling across Mars for ten years and has helped uncover many details of the wet and windy past of Earth's planetary neighbor. After taking this and other images, Curiosity carefully navigated stones and slippery sand to climb up Marker Band Valley.

Tomorrow's picture: black hole galaxy


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