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.

                              2026 September 8
   [2]A dark field has a bright circular disk near the center. Around the
     center of this disk are bands. One of the bands appear particularly
   geometric and appears to have 10 sides. Please see the explanation for
                         more detailed information.

                 Hubble: Decagon Around Saturn's South Pole
   Image Credit: [3]NASA, [4]ESA, [5]STScI, [6]HST; [7]A. Sánchez-Lavega
     ([8]UPV), A. Simon (NASA-GSFC), M. Wong (UC Berkeley); Processing:
                           [9]A. Pagan ([10]STScI)

   Explanation: Why are Saturn’s poles geometric? [11]Saturn’s North Pole
   has been known to be surrounded by a [12]hexagonal (6 sides) cloud
   since [13]discovery in 1987 in data taken by NASA’s [14]Voyager
   spacecrafts, which quickly flew past the [15]ringed world in the early
   1980s. Now, recent observations of Saturn by the [16]Hubble Space
   Telescope reveal a slightly different geometric cloud pattern around
   the South Pole: a [17]decagon (10 [18]sides). The geometric boundaries
   are [19]possibly caused by waves when the fast-moving gas away from the
   poles interacts with slower-moving gas closer to the poles. In the
   [20]featured image composite by the Hubble taken last year, the
   [21]South Pole of Saturn is marked by an X and surrounded by bands of
   circulating clouds. The [22]decagon appears most prominent in the dark
   inner regions. The [23]northern hexagon has proven stable for over 40
   years, while the stability of the southern decagon will surely remain a
   [24]topic of research.

       APOD's main NASA site is [25]moving: From [26]apod.nasa.gov to
                          [27]science.nasa.gov/apod
                       Tomorrow's picture: open space
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    Authors & editors: [39]Robert Nemiroff ([40]MTU) & [41]Jerry Bonnell
                                 ([42]UMCP)
          NASA Official: Amber Straughn [43]Specific rights apply.
            [44]NASA Web Privacy, [45]Accessibility, [46]Notices;
                A service of: [47]ASD at [48]NASA / [49]GSFC,
                         [50]NASA Science Activation
                           & [51]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2609/SaturnDecagon_Hubble_960.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://www.stsci.edu/
   6. https://science.nasa.gov/mission/hubble/
   7. https://ekoizpen-zientifikoa.ehu.eus/investigadores/128754/detalle
   8. https://www.ehu.eus/
   9. https://www.linkedin.com/in/alyssa-pagan-058170144
  10. https://www.stsci.edu/
  11. https://science.nasa.gov/saturn/
  12. https://apod.nasa.gov/apod/ap230618.html
  13. https://ui.adsabs.harvard.edu/abs/1988Icar...76..335G/abstract
  14. https://science.nasa.gov/mission/voyager/
  15. https://science.nasa.gov/image-article/apod-2020-april-19-cassini-approaches-saturn/
  16. https://apod.nasa.gov/apod/ap090525.html
  17. https://mathworld.wolfram.com/Decagon.html
  18. https://www.geogebra.org/m/bbD4R2Ck
  19. https://youtu.be/VQzLY17ncWM
  20. https://science.nasa.gov/missions/hubble/nasas-hubble-tracks-new-decagon-encircling-saturns-south-pole/
  21. https://apod.nasa.gov/apod/ap081027.html
  22. https://science.nasa.gov/asset/hubble/decagon-on-saturns-south-pole-single-filter/
  23. https://apod.nasa.gov/apod/ap180907.html
  24. https://unsplash.com/photos/white-and-black-cat-on-white-textile-ZsMhJkloV64
  25. https://asterisk.apod.com/viewtopic.php?t=45023
  26. https://apod.nasa.gov/
  27. https://science.nasa.gov/apod
  28. https://apod.nasa.gov/apod/ap260907.html
  29. https://apod.nasa.gov/apod/archivepix.html
  30. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  31. https://apod.nasa.gov/apod/lib/aptree.html
  32. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  33. https://apod.nasa.gov/apod/calendar/allyears.html
  34. https://apod.com/feed.rss
  35. https://apod.nasa.gov/apod/lib/edlinks.html
  36. https://apod.nasa.gov/apod/lib/about_apod.html
  37. https://asterisk.apod.com/discuss_apod.php?date=260908
  38. https://apod.nasa.gov/apod/ap260909.html
  39. https://www.mtu.edu/physics/department/faculty/nemiroff/
  40. https://www.mtu.edu/physics/
  41. https://inspirehep.net/authors/1073087
  42. http://www.astro.umd.edu/
  43. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  44. https://www.nasa.gov/about/highlights/HP_Privacy.html
  45. https://www.nasa.gov/general/accessibility/
  46. https://www.nasa.gov/privacy/
  47. https://science.gsfc.nasa.gov/astrophysics/
  48. https://www.nasa.gov/
  49. https://www.nasa.gov/centers/goddard/
  50. https://science.nasa.gov/learn/about-science-activation/
  51. http://www.mtu.edu/