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.

                              2024 December 19
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                                  Messier 2
         Image Credit: [3]ESA/Hubble & [4]NASA, [5]G. Piotto et al.

   Explanation: [6]After the Crab Nebula, this giant star cluster is the
   second entry in 18th century astronomer Charles Messier's famous list
   of things that are not comets. M2 is one of the largest globular star
   clusters now known to roam the halo of our Milky Way galaxy. Though
   Messier originally described it as a nebula without stars, this
   [7]stunning Hubble image resolves stars across the cluster's central 40
   light-years. [8]Its population of stars numbers close to 150,000,
   concentrated within a total diameter of around 175 light-years. About
   55,000 light-years distant toward the constellation Aquarius, this
   ancient denizen of the Milky Way, also [9]known as NGC 7089, is 13
   billion years old. An extended [10]stellar debris stream, a signature
   of past gravitational tidal disruption, was recently found to be
   [11]associated with Messier 2.

                   Tomorrow's picture: the last full moon
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    Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell
                                 ([26]UMCP)
          NASA Official: Amber Straughn [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/2412/potw1913aa.jpg
   3. https://spacetelescope.org/
   4. https://www.nasa.gov/
   5. https://arxiv.org/abs/1410.4564
   6. https://apod.nasa.gov/apod/ap180104.html
   7. https://spacetelescope.org/images/potw1913a/
   8. http://www.messier.seds.org/m/m002.html
   9. https://arxiv.org/abs/1606.05949
  10. https://apod.nasa.gov/apod/ap240927.html
  11. https://ui.adsabs.harvard.edu/abs/2022ApJ...929...89G/abstract
  12. https://apod.nasa.gov/apod/ap241218.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=241219
  22. https://apod.nasa.gov/apod/ap241220.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/