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                        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.

                                2020 July 21
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                        Iron in the Butterfly Nebula
     Image Credit: [3]NASA, [4]ESA, [5]Hubble; Processing & [6]License:
                               [7]Judy Schmidt

   Explanation: Can stars, like caterpillars, transform themselves into
   butterflies? No, but in the case of the [8]Butterfly Nebula -- it sure
   looks like it. Though its wingspan covers over 3 [9]light-years and its
   estimated surface temperature exceeds 200,000 degrees, [10]C, the dying
   central star of NGC 6302, the featured [11]planetary nebula, has become
   exceptionally hot, shining brightly in [12]visible and [13]ultraviolet
   light but hidden from direct view by a dense torus of dust. [14]This
   sharp close-up was recorded by the [15]Hubble Space Telescope and is
   reprocessed here to show off the remarkable details of the complex
   [16]planetary nebula, highlighting in particular light emitted by
   [17]iron, shown in red. [18]NGC 6302 lies about 4,000 light-years away
   in the [19]arachnologically correct constellation of the Scorpion
   ([20]Scorpius). [21]Planetary nebulas evolve from outer atmospheres of
   [22]stars like our [23]Sun, but usually fade in about 20,000 years.

   Great Debates in Astronomy: [24]2020: How will humanity first discover
                           extraterrestrial life?
                       Tomorrow's picture: open space
     __________________________________________________________________

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    Authors & editors: [36]Robert Nemiroff ([37]MTU) & [38]Jerry Bonnell
                                 ([39]UMCP)
          NASA Official: Phillip Newman [40]Specific rights apply.
              [41]NASA Web Privacy Policy and Important Notices
                A service of: [42]ASD at [43]NASA / [44]GSFC
                           & [45]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2007/Butterfly_HubbleSchmidt_4767.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://hla.stsci.edu/
   6. https://creativecommons.org/licenses/by/2.0/
   7. https://geckzilla.com/
   8. https://en.wikipedia.org/wiki/Butterfly
   9. https://exoplanets.nasa.gov/faq/26/what-is-a-light-year/
  10. https://en.wikipedia.org/wiki/Celsius
  11. https://www.nasa.gov/mission_pages/chandra/multimedia/planetary_nebula.html
  12. https://science.nasa.gov/ems/09_visiblelight
  13. https://science.nasa.gov/ems/10_ultravioletwaves
  14. https://www.flickr.com/photos/geckzilla/50023499248/
  15. https://www.nasa.gov/mission_pages/hubble/story/index.html
  16. https://apod.nasa.gov/apod/ap190929.html
  17. https://periodic.lanl.gov/26.shtml
  18. https://en.wikipedia.org/wiki/NGC_6302
  19. https://en.wikipedia.org/wiki/Arachnid
  20. http://hawastsoc.org/deepsky/sco/index.html
  21. https://en.wikipedia.org/wiki/Planetary_nebula
  22. https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve
  23. https://apod.nasa.gov/apod/ap190526.html
  24. https://apod.nasa.gov/debate/debate100th.html
  25. https://apod.nasa.gov/apod/ap200720.html
  26. https://apod.nasa.gov/apod/archivepix.html
  27. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  28. https://apod.nasa.gov/apod/lib/aptree.html
  29. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  30. https://apod.nasa.gov/apod/calendar/allyears.html
  31. https://apod.nasa.gov/apod.rss
  32. https://apod.nasa.gov/apod/lib/edlinks.html
  33. https://apod.nasa.gov/apod/lib/about_apod.html
  34. http://asterisk.apod.com/discuss_apod.php?date=200721
  35. https://apod.nasa.gov/apod/ap200722.html
  36. http://www.phy.mtu.edu/faculty/Nemiroff.html
  37. http://www.phy.mtu.edu/
  38. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  39. http://www.astro.umd.edu/
  40. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  41. https://www.nasa.gov/about/highlights/HP_Privacy.html
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. http://www.mtu.edu/