                        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.

                                2022 March 9

                        A Flower-Shaped Rock on Mars
                    Image Credit: NASA, JPL-Caltech, MSSS

   Explanation: It is one of the more unusual rocks yet found on Mars.
   Smaller than a penny, the rock has several appendages that make it
   look, to some, like a flower. Although it would be a major discovery if
   the rock was truly a fossilized ancient Martian flower, there are less
   spectacular -- and currently preferred -- explanations for its unusual
   structure. One theory that has emerged is that the rock is a type of
   concretion created by minerals deposited by water in cracks or
   divisions in existing rock. These concretions can be compacted
   together, can be harder and denser than surrounding rock, and can
   remain even after the surrounding rock erodes away. The flower
   structure may also be caused by crystal clusters. The small rock, named
   Blackthorn Salt, has similarities to previously imaged Martian pebbles.
   The featured image was taken by the Curiosity rover on Mars in late
   February. Scientists will continue to study data and images taken of
   this -- and similar -- surprising Martian rocks.

                     Review: Last Year in Space Pictures
                Tomorrow's picture: the toucan's star cluster
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.

