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 March 17
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                              The Medusa Nebula
         Image Credit & [3]Copyright: Martin Bradley [4]Chesterfield
                            Astronomical Society

   Explanation: Braided and serpentine filaments of glowing gas suggest
   this nebula's popular name, The Medusa Nebula. [5]Also known as Abell
   21, this Medusa is an old planetary nebula some 1,500 light-years away
   in the constellation Gemini. Like its [6]mythological namesake, the
   nebula is associated with a dramatic transformation. The [7]planetary
   nebula phase represents a final stage in [8]the evolution of low mass
   stars like the sun as they transform themselves from [9]red giants to
   hot white dwarf stars and in the process shrug off their outer layers.
   Ultraviolet [10]radiation from the hot star powers the nebular glow.
   The Medusa's transforming star is the faint one near the center of the
   overall bright crescent shape. In this deep telescopic view, fainter
   filaments clearly extend below and right of the bright crescent region.
   The Medusa Nebula is estimated to be over [11]4 light-years across.

                   Tomorrow's picture: supernova's prelude
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    Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell
                                 ([26]UMCP)
          NASA Official: Phillip Newman [27]Specific rights apply.
              [28]NASA Web Privacy Policy and Important Notices
                A service of: [29]ASD at [30]NASA / [31]GSFC,
                         [32]NASA Science Activation
                           & [33]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2303/medusaNeb.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://chesterfield-observatory.co.uk/events/pretty-pictures-from-ugly-pixels-using-gimp-martin-bradley-cas-member/
   5. https://noirlab.edu/public/images/noaoann09008a/
   6. http://en.wikipedia.org/wiki/Medusa
   7. https://en.wikipedia.org/wiki/Planetary_nebula
   8. http://casswww.ucsd.edu/public/tutorial/StevI.html
   9. http://en.wikipedia.org/wiki/Red_giant
  10. https://science.nasa.gov/ems/01_intro
  11. https://www.nasa.gov/content/discoveries-hubbles-nebulae
  12. https://apod.nasa.gov/apod/ap230316.html
  13. https://apod.nasa.gov/apod/archivepix.html
  14. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  15. https://apod.nasa.gov/apod/lib/aptree.html
  16. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  17. https://apod.nasa.gov/apod/calendar/allyears.html
  18. https://apod.nasa.gov/apod.rss
  19. https://apod.nasa.gov/apod/lib/edlinks.html
  20. https://apod.nasa.gov/apod/lib/about_apod.html
  21. http://asterisk.apod.com/discuss_apod.php?date=230317
  22. https://apod.nasa.gov/apod/ap230318.html
  23. http://www.phy.mtu.edu/faculty/Nemiroff.html
  24. http://www.phy.mtu.edu/
  25. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  26. http://www.astro.umd.edu/
  27. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  28. https://www.nasa.gov/about/highlights/HP_Privacy.html
  29. https://astrophysics.gsfc.nasa.gov/
  30. https://www.nasa.gov/
  31. https://www.nasa.gov/centers/goddard/
  32. https://science.nasa.gov/learners
  33. http://www.mtu.edu/