                        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.

                              2024 December 16
   A black and white image shows, from the side, the wall of a high jagged
      cliff. At the bottom of the cliff is a smooth landing dotted with
      rocks. Please see the explanation for more detailed information.

           A Kilometer High Cliff on Comet Churyumov - Gerasimenko
     Image Credit & Licence (CC BY-SA 3.0 IGO): ESA, Rosetta spacecraft,
               NAVCAM; Additional Processing: Stuart Atkinson

   Explanation: This kilometer high cliff occurs on the surface of a
   comet. It was discovered on the dark nucleus of Comet Churyumov -
   Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA,
   which orbited the comet from 2014 to 2016. The ragged cliff, as
   featured here, was imaged by Rosetta early in its mission. Although
   towering about one kilometer high, the low surface gravity of Comet CG
   would likely make a jump from the cliffs by a human survivable. At the
   foot of the cliffs is relatively smooth terrain dotted with boulders as
   large as 20 meters across. Data from Rosetta indicates that the ice in
   Comet CG has a significantly different deuterium fraction -- and hence
   likely a different origin -- than the water in Earth's oceans. The
   probe was named after the Rosetta Stone, a rock slab featuring the same
   text written in three different languages that helped humanity decipher
   ancient Egyptian writing.

                    Tomorrow's picture: near to the heart
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                  NASA Web Privacy, Accessibility, Notices;
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

