Astronomy Picture of the Day

   [1]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.

                              2021 November 28
   [2]The featured image shows a kilometer-high cliff that occurs on Comet
    Churyumov-Gerasimenko as imaged by ESA's Rosetta spacecraft in 2014.
          Please see the explanation for more detailed information.

                 A High Cliff on Comet Churyumov-Gerasimenko
      Image Credit & [3]Licence: [4]ESA, [5]Rosetta spacecraft, NAVCAM;
                  Additional Processing: [6]Stuart Atkinson

   Explanation: This high cliff occurs not on a planet, not on a moon, but
   on a comet. It was discovered to be part of the dark nucleus of
   [7]Comet Churyumov-Gerasimenko (CG) by [8]Rosetta, a robotic spacecraft
   [9]launched by [10]ESA that rendezvoused with the Sun-orbiting comet in
   2014. The ragged cliff, as [11]featured [12]here, was imaged by Rosetta
   in 2014. Although towering about one kilometer high, the low surface
   gravity of [13]Comet CG would likely make it an [14]accessible climb --
   and even a [15]jump from the [16]cliff survivable. At the foot of the
   cliff is relatively smooth terrain dotted with [17]boulders as large as
   20 meters across. Data from [18]Rosetta indicates that the ice in
   [19]Comet CG has a significantly different [20]deuterium fraction --
   and hence likely a [21]different origin -- than the water in Earth's
   oceans. [22]Rosetta ended its mission with a controlled impact onto
   Comet CG in 2016. [23]Comet CG has just completed another close
   approach to Earth and [24]remains visible through a small telescope.

                    Tomorrow's picture: stellar pinwheel
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    Authors & editors: [36]Robert Nemiroff ([37]MTU) & [38]Jerry Bonnell
                                 ([39]UMCP)
          NASA Official: Phillip Newman [40]Specific rights apply.
              [41]NASA Web Privacy Policy and Important Notices
                A service of: [42]ASD at [43]NASA / [44]GSFC
                           & [45]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2111/cometcliffs_RosettaAtkinson_960.jpg
   3. https://creativecommons.org/licenses/by-sa/3.0/igo/
   4. https://www.esa.int/
   5. https://www.esa.int/Science_Exploration/Space_Science/Rosetta
   6. https://cumbriansky.wordpress.com/about/
   7. https://en.wikipedia.org/wiki/67P/Churyumov%E2%80%93Gerasimenko
   8. https://en.wikipedia.org/wiki/Rosetta_(spacecraft)
   9. https://apod.nasa.gov/apod/ap091123.html
  10. https://www.esa.int/
  11. http://www.esa.int/spaceinimages/Images/2014/12/Comet_on_10_December_2014_NavCam
  12. https://cumbriansky.wordpress.com/2014/12/17/the-cliffs-of-churyumov-gerasimenko/
  13. http://blogs.esa.int/rosetta/2014/12/15/cometwatch-10-december/
  14. https://img4.findglocal.com/701/514/1101350047015142.jpg
  15. https://apod.nasa.gov/apod/ap140210.html
  16. https://apod.nasa.gov/apod/ap201129.html
  17. https://blogs.esa.int/rosetta/2014/10/09/boulder-close-up/
  18. https://solarsystem.nasa.gov/missions/rosetta-philae/in-depth/
  19. https://solarsystem.nasa.gov/asteroids-comets-and-meteors/comets/67p-churyumov-gerasimenko/in-depth/
  20. https://en.wikipedia.org/wiki/Deuterium
  21. https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Rosetta_fuels_debate_on_origin_of_Earth_s_oceans
  22. https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Mission_complete_Rosetta_s_journey_ends_in_daring_descent_to_comet
  23. https://apod.nasa.gov/apod/ap211022.html
  24. https://earthsky.org/astronomy-essentials/famous-comet-67p-c-g-closest-nov-2021-until-2214/
  25. https://apod.nasa.gov/apod/ap211127.html
  26. https://apod.nasa.gov/apod/archivepix.html
  27. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  28. https://apod.nasa.gov/apod/lib/aptree.html
  29. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  30. https://apod.nasa.gov/apod/calendar/allyears.html
  31. https://apod.nasa.gov/apod.rss
  32. https://apod.nasa.gov/apod/lib/edlinks.html
  33. https://apod.nasa.gov/apod/lib/about_apod.html
  34. http://asterisk.apod.com/discuss_apod.php?date=211128
  35. https://apod.nasa.gov/apod/ap211129.html
  36. http://www.phy.mtu.edu/faculty/Nemiroff.html
  37. http://www.phy.mtu.edu/
  38. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  39. http://www.astro.umd.edu/
  40. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  41. https://www.nasa.gov/about/highlights/HP_Privacy.html
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. http://www.mtu.edu/