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.

                              2025 September 28
    [2]Part of a large rock on Mars is shown being mostly orange. On the
     rock are several irregular light-colored areas surrounded by a dark
    border. The spots are only millimeters across but might be a remnant
    biosignature of ancient Martian life. Please see the explanation for
                         more detailed information.

                       Leopard Spots on Martian Rocks
    Image Credit: [3]NASA, [4]JPL-Caltech, [5]MSSS, [6]Perseverance Rover

   Explanation: What is creating these unusual spots? Light-colored spots
   on [7]Martian rocks, each surrounded by a dark border, were discovered
   last year by [8]NASA's [9]Perseverance Rover currently exploring
   [10]Mars. Dubbed [11]leopard spots because of their seemingly
   similarity to markings on famous [12]Earth-bound predators, these
   curious patterns are being studied with the possibility they were
   created by [13]ancient Martian life. The [14]pictured spots measure
   only [15]millimeters across and were discovered on a [16]larger rock
   named [17]Cheyava Falls. The exciting but [18]unproven speculation is
   that long ago, [19]microbes generated energy with chemical reactions
   that turned rock from red to white while leaving a dark biosignature
   ring, like some [20]similarly appearing spots on [21]Earth rocks.
   Although other [22]non-biological explanations have not been ruled out,
   speculation focusing on this potential biological origin is causing
   [23]much intrigue.

                       Tomorrow's picture: comet comet
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    Authors & editors: [35]Robert Nemiroff ([36]MTU) & [37]Jerry Bonnell
                                 ([38]UMCP)
          NASA Official: Amber Straughn [39]Specific rights apply.
            [40]NASA Web Privacy, [41]Accessibility, [42]Notices;
                A service of: [43]ASD at [44]NASA / [45]GSFC,
                         [46]NASA Science Activation
                           & [47]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2509/LeopardSpots_Perseverance_1648.jpg
   3. https://www.nasa.gov/
   4. https://www.jpl.nasa.gov/
   5. https://www.msss.com/
   6. https://science.nasa.gov/mission/mars-2020-perseverance/
   7. https://apod.nasa.gov/apod/ap991030.html
   8. https://www.nasa.gov/
   9. https://science.nasa.gov/mission/mars-2020-perseverance/
  10. https://science.nasa.gov/mars/
  11. https://en.wikipedia.org/wiki/Leopard#/media/File:African_leopard_male_(cropped).jpg
  12. https://img.freepik.com/premium-photo/front-view-kitten-hunting-pose_7502-2520.jpg
  13. https://science.nasa.gov/blogs/was-there-life-on-mars/
  14. https://science.nasa.gov/resource/perseverance-finds-a-rock-with-leopard-spots/
  15. https://www.quora.com/What-is-something-the-size-of-a-millimeter
  16. https://www.flickr.com/photos/lunexit/53885766401/in/pool-apods/
  17. https://youtu.be/bknMDwCjFHo"
  18. https://www.scientificamerican.com/article/nasas-perseverance-rover-discovers-a-rock-that-may-contain-alien/
  19. https://en.wikipedia.org/wiki/Microorganism
  20. https://www.atlasobscura.com/articles/earliest-life-on-earth-rocks
  21. https://www.geocaching.com/geocache/GC3T4BT
  22. https://en.wikipedia.org/wiki/Hematite#Mars
  23. https://www.nasa.gov/news-release/nasa-says-mars-rover-discovered-potential-biosignature-last-year/
  24. https://apod.nasa.gov/apod/ap250927.html
  25. https://apod.nasa.gov/apod/archivepix.html
  26. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  27. https://apod.nasa.gov/apod/lib/aptree.html
  28. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  29. https://apod.nasa.gov/apod/calendar/allyears.html
  30. https://apod.com/feed.rss
  31. https://apod.nasa.gov/apod/lib/edlinks.html
  32. https://apod.nasa.gov/apod/lib/about_apod.html
  33. https://asterisk.apod.com/discuss_apod.php?date=250928
  34. https://apod.nasa.gov/apod/ap250929.html
  35. http://www.phy.mtu.edu/faculty/Nemiroff.html
  36. http://www.phy.mtu.edu/
  37. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  38. http://www.astro.umd.edu/
  39. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  40. https://www.nasa.gov/about/highlights/HP_Privacy.html
  41. https://www.nasa.gov/general/accessibility/
  42. https://www.nasa.gov/privacy/
  43. https://astrophysics.gsfc.nasa.gov/
  44. https://www.nasa.gov/
  45. https://www.nasa.gov/centers/goddard/
  46. https://science.nasa.gov/learners
  47. http://www.mtu.edu/