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 April 16
      [2]A dark starfield is dominated by a green nebula with intricate
     filaments all around. At the center is a bright glow surrounding a
   central star. Please see the explanation for more detailed information.

                            Halo of the Cat's Eye
    Image Credit & Copyright: [3]Taavi Niittee ([4]Tõrva Astronomy Club)

   Explanation: What created the unusual halo around the Cat's Eye Nebula?
   No one is sure. What is sure is that the [5]Cat's Eye Nebula (NGC 6543)
   is one of the best known [6]planetary nebulae on the sky. Although
   haunting symmetries are seen in the bright [7]central region, [8]this
   image was taken to feature its intricately structured outer halo, which
   spans over three [9]light-years across. [10]Planetary nebulae have long
   been appreciated as a final phase [11]in the life of a Sun-like star.
   Only recently however, have some planetaries been [12]found to have
   expansive halos, likely formed from material shrugged off during
   earlier [13]puzzling episodes in the [14]star's evolution. While the
   [15]planetary nebula phase is [16]thought to last for around 10,000
   years, astronomers estimate the age of the [17]outer filamentary
   portions of the [18]Cat's Eye Nebula's halo to be 50,000 to 90,000
   years.

                      Tomorrow's picture: star cylinder
     __________________________________________________________________

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    Authors & editors: [30]Robert Nemiroff ([31]MTU) & [32]Jerry Bonnell
                                 ([33]UMCP)
          NASA Official: Amber Straughn [34]Specific rights apply.
            [35]NASA Web Privacy, [36]Accessibility, [37]Notices;
                A service of: [38]ASD at [39]NASA / [40]GSFC,
                         [41]NASA Science Activation
                           & [42]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2504/CatsEyeWide_Niittee_960.jpg
   3. https://app.astrobin.com/u/Astronoomiaklubi#gallery
   4. https://www.facebook.com/torvaastronoomiaklubi
   5. https://apod.nasa.gov/apod/ap220710.html
   6. https://en.wikipedia.org/wiki/Planetary_nebula
   7. https://apod.nasa.gov/apod/ap240107.html
   8. https://www.facebook.com/photo.php?fbid=1231078905687113&set=pb.100063550452442.-2207520000&type=3
   9. https://spaceplace.nasa.gov/light-year/
  10. https://youtu.be/Mj06h8BeeOA
  11. https://science.nasa.gov/universe/stars/
  12. https://apod.nasa.gov/apod/ap140522.html
  13. https://www.aanda.org/articles/aa/full_html/2018/12/aa33981-18/aa33981-18.html
  14. https://en.wikipedia.org/wiki/Stellar_evolution
  15. https://astronomy.swin.edu.au/cosmos/p/Planetary+Nebulae
  16. https://cdn.pixabay.com/photo/2019/09/04/08/24/cat-4451003_1280.jpg
  17. https://youtu.be/tw0VJ1K93PM
  18. https://en.wikipedia.org/wiki/Cat's_Eye_Nebula
  19. https://apod.nasa.gov/apod/ap250415.html
  20. https://apod.nasa.gov/apod/archivepix.html
  21. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  22. https://apod.nasa.gov/apod/lib/aptree.html
  23. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  24. https://apod.nasa.gov/apod/calendar/allyears.html
  25. https://apod.com/feed.rss
  26. https://apod.nasa.gov/apod/lib/edlinks.html
  27. https://apod.nasa.gov/apod/lib/about_apod.html
  28. https://asterisk.apod.com/discuss_apod.php?date=250416
  29. https://apod.nasa.gov/apod/ap250417.html
  30. http://www.phy.mtu.edu/faculty/Nemiroff.html
  31. http://www.phy.mtu.edu/
  32. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  33. http://www.astro.umd.edu/
  34. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  35. https://www.nasa.gov/about/highlights/HP_Privacy.html
  36. https://www.nasa.gov/general/accessibility/
  37. https://www.nasa.gov/privacy/
  38. https://astrophysics.gsfc.nasa.gov/
  39. https://www.nasa.gov/
  40. https://www.nasa.gov/centers/goddard/
  41. https://science.nasa.gov/learners
  42. http://www.mtu.edu/