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 July 14
    [2]An unusual galaxy is shown that appears lens-like in overall shape
      yet has various rings of stars around the center. Please see the
                 explanation for more detailed information.

                         NGC 2685: The Helix Galaxy
                  Image Credit & Copyright: [3]Stefan Thrun

   Explanation: What is going on with this galaxy? [4]NGC 2685 is a
   confirmed polar ring galaxy - a rare [5]type of galaxy with stars, gas
   and dust orbiting in rings perpendicular to the plane of a flat
   galactic disk. The [6]bizarre configuration could be caused by the
   chance [7]capture of material from another galaxy by a disk galaxy,
   with the captured debris strung out in a rotating ring. Still, observed
   [8]properties of NGC 2685 suggest that the rotating [9]helix structure
   is remarkably old and stable. [10]In this sharp view of the peculiar
   system also known as [11]Arp 336 or the Helix galaxy, the strange,
   perpendicular rings are easy to trace as they pass in front of the
   galactic disk, along with other [12]disturbed outer structures. NGC
   2685 is about 50,000 [13]light-years across and 40 million light-years
   away in the constellation of the Great Bear ([14]Ursa Major).

           Piece it All Together: [15]Astronomy Puzzle of the Day
                    Tomorrow's picture: collapse on Mars
     __________________________________________________________________

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    Authors & editors: [27]Robert Nemiroff ([28]MTU) & [29]Jerry Bonnell
                                 ([30]UMCP)
          NASA Official: Amber Straughn [31]Specific rights apply.
            [32]NASA Web Privacy, [33]Accessibility, [34]Notices;
                A service of: [35]ASD at [36]NASA / [37]GSFC,
                         [38]NASA Science Activation
                           & [39]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2507/Ngc2685_Thrun_960.jpg
   3. https://www.astrobin.com/users/Stefan-Harry-Thrun/
   4. https://en.wikipedia.org/wiki/NGC_2685
   5. https://science.nasa.gov/universe/galaxies/types/
   6. https://apod.nasa.gov/apod/ap121110.html
   7. https://apod.nasa.gov/apod/ap190325.html
   8. https://ui.adsabs.harvard.edu/abs/2009A&A...494..489J/abstract
   9. https://mathinsight.org/applet/parametrized_helix
  10. https://www.astrobin.com/3a3kzg/B/
  11. http://nedwww.ipac.caltech.edu/level5/Arp/frames.html
  12. https://www.meowingtons.com/cdn/shop/articles/Screen_Shot_2019-04-18_at_4.13.33_PM.png
  13. https://spaceplace.nasa.gov/light-year/
  14. https://en.wikipedia.org/wiki/Ursa_Major
  15. https://www.scigames.org/apps/webjigsaw2/index.php
  16. https://apod.nasa.gov/apod/ap250713.html
  17. https://apod.nasa.gov/apod/archivepix.html
  18. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  19. https://apod.nasa.gov/apod/lib/aptree.html
  20. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  21. https://apod.nasa.gov/apod/calendar/allyears.html
  22. https://apod.com/feed.rss
  23. https://apod.nasa.gov/apod/lib/edlinks.html
  24. https://apod.nasa.gov/apod/lib/about_apod.html
  25. https://asterisk.apod.com/discuss_apod.php?date=250714
  26. https://apod.nasa.gov/apod/ap250715.html
  27. http://www.phy.mtu.edu/faculty/Nemiroff.html
  28. http://www.phy.mtu.edu/
  29. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  30. http://www.astro.umd.edu/
  31. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  32. https://www.nasa.gov/about/highlights/HP_Privacy.html
  33. https://www.nasa.gov/general/accessibility/
  34. https://www.nasa.gov/privacy/
  35. https://astrophysics.gsfc.nasa.gov/
  36. https://www.nasa.gov/
  37. https://www.nasa.gov/centers/goddard/
  38. https://science.nasa.gov/learners
  39. http://www.mtu.edu/