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 December 14
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                       Supernova Remnant Cassiopeia A
      Image Credit: [3]NASA, [4]ESA, [5]CSA, [6]STScI; D. Milisavljevic
      (Purdue University), T. Temim (Princeton University), I. De Looze
                            (University of Gent)

   Explanation: [7]Massive stars in our Milky Way Galaxy live spectacular
   lives. Collapsing from vast cosmic clouds, their nuclear furnaces
   ignite and create heavy elements in their cores. After only a few
   million years for the most massive stars, the [8]enriched material is
   blasted back into interstellar space where star formation can begin
   anew. The expanding debris cloud known as Cassiopeia A is an example of
   this final phase of the [9]stellar life cycle. Light from the supernova
   explosion that created this remnant would have been first [10]seen in
   planet Earth's sky about 350 years ago, although it took that light
   11,000 years to reach us. [11]This sharp NIRCam image from the James
   Webb Space Telescope shows the still hot filaments and knots in the
   supernova remnant. The whitish, smoke-like outer shell of the expanding
   blast wave is about 20 light-years across, while the [12]bright speck
   near center is a neutron star, the incredibly dense, collapsed remains
   of the massive stellar core. Light echoes from the massive star's
   cataclysmic explosion are also [13]identified in Webb's detailed image
   of supernova remnant Cassiopeia A.

                       Tonight watch: [14]The Geminids
                     Tomorrow's picture: stellar eclipse
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    Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell
                                 ([29]UMCP)
          NASA Official: Phillip Newman [30]Specific rights apply.
              [31]NASA Web Privacy Policy and Important Notices
                A service of: [32]ASD at [33]NASA / [34]GSFC,
                         [35]NASA Science Activation
                           & [36]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2312/CasA_nircam_4096.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://www.asc-csa.gc.ca/eng/
   6. https://www.stsci.edu/
   7. https://en.wikipedia.org/wiki/Stellar_evolution#Massive_stars
   8. https://apod.nasa.gov/apod/ap190801.html
   9. https://universe.nasa.gov/stars/basics/
  10. https://spider.seds.org/spider/Vars/casA.html
  11. https://webbtelescope.org/contents/media/images/2023/149/01HGGZ4TPD8XFNPCBTZ2QYM0ZM
  12. https://apod.nasa.gov/apod/ap170501.html
  13. https://webbtelescope.org/contents/media/images/2023/149/01HGGZDJX7RZR07HWZ6YEQ74CR
  14. https://earthsky.org/astronomy-essentials/everything-you-need-to-know-geminid-meteor-shower/
  15. https://apod.nasa.gov/apod/ap231213.html
  16. https://apod.nasa.gov/apod/archivepix.html
  17. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  18. https://apod.nasa.gov/apod/lib/aptree.html
  19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  20. https://apod.nasa.gov/apod/calendar/allyears.html
  21. https://apod.nasa.gov/apod.rss
  22. https://apod.nasa.gov/apod/lib/edlinks.html
  23. https://apod.nasa.gov/apod/lib/about_apod.html
  24. http://asterisk.apod.com/discuss_apod.php?date=231214
  25. https://apod.nasa.gov/apod/ap231215.html
  26. http://www.phy.mtu.edu/faculty/Nemiroff.html
  27. http://www.phy.mtu.edu/
  28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  29. http://www.astro.umd.edu/
  30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  31. https://www.nasa.gov/about/highlights/HP_Privacy.html
  32. https://astrophysics.gsfc.nasa.gov/
  33. https://www.nasa.gov/
  34. https://www.nasa.gov/centers/goddard/
  35. https://science.nasa.gov/learners
  36. http://www.mtu.edu/