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.

                               2023 October 3
    [2]A vertical planetary nebula is shown in orange around the outside
   but with a blue glow in the center. The outside is shaped like a tilted
    hourglass, while the inside appears similar to an eye. Please see the
                 explanation for more detailed information.

              MyCn 18: The Engraved Hourglass Planetary Nebula
        Image Credit & Copyright: [3]NASA, [4]ESA, [5]Hubble, [6]HLA;
               Processing & Copyright: [7]Harshwardhan Pathak

   Explanation: Do you see the hourglass shape -- or does it see you? If
   you can picture it, the rings of [8]MyCn 18 trace the outline of an
   hourglass -- although one with an unusual eye in its center. Either
   way, the sands of time are running out for the central star of this
   hourglass-shaped [9]planetary nebula. With its [10]nuclear fuel
   exhausted, this brief, spectacular, closing phase of a [11]Sun-like
   [12]star's life occurs as its outer layers are ejected - its core
   becoming a cooling, fading [13]white dwarf. In 1995, astronomers used
   the [14]Hubble Space Telescope (HST) to make a series of images of
   [15]planetary nebulae, including the one featured here. Pictured,
   delicate rings of colorful glowing gas ([16]nitrogen-red,
   [17]hydrogen-green, and [18]oxygen-blue) outline the tenuous walls of
   the [19]hourglass. The unprecedented sharpness of the Hubble images has
   revealed [20]surprising details of the [21]nebula ejection process that
   are helping to resolve the outstanding mysteries of the [22]complex
   shapes and symmetries of planetary nebulas like MyCn 18.

                       Tomorrow's picture: witch head?
     __________________________________________________________________

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    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Phillip Newman [38]Specific rights apply.
              [39]NASA Web Privacy Policy and Important Notices
                A service of: [40]ASD at [41]NASA / [42]GSFC,
                         [43]NASA Science Activation
                           & [44]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2310/Hourglass_HubblePathak_1080.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://www.nasa.gov/mission_pages/hubble/about
   6. https://hla.stsci.edu/
   7. https://www.instagram.com/mr.cosmic.wanderer/
   8. https://en.wikipedia.org/wiki/Engraved_Hourglass_Nebula
   9. https://en.wikipedia.org/wiki/Planetary_nebula
  10. https://www.nasa.gov/directorates/spacetech/game_changing_development/Nuclear_Thermal_Propulsion_Deep_Space_Exploration
  11. https://science.nasa.gov/sun/
  12. http://apod.pl/htmltest/gifcity/msblues.html
  13. https://apod.nasa.gov/apod/ap000910.html
  14. https://apod.nasa.gov/apod/ap010806.html
  15. https://esahubble.org/wordbank/planetary-nebula/
  16. https://periodic.lanl.gov/7.shtml
  17. http://www.youtube.com/watch?v=lFptgQ8GA_U
  18. http://education.jlab.org/itselemental/ele008.html
  19. https://en.wikipedia.org/wiki/Hourglass
  20. https://ui.adsabs.harvard.edu/abs/2018PASA...35...27M/abstract
  21. https://apod.nasa.gov/apod/ap200630.html
  22. http://faculty.washington.edu/balick/pPNe/
  23. https://apod.nasa.gov/apod/ap231002.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.nasa.gov/apod.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. https://asterisk.apod.com/discuss_apod.php?date=231003
  33. https://apod.nasa.gov/apod/ap231004.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://astrophysics.gsfc.nasa.gov/
  41. https://www.nasa.gov/
  42. https://www.nasa.gov/centers/goddard/
  43. https://science.nasa.gov/learners
  44. http://www.mtu.edu/