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.

                               2019 December 1
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                      Starburst Galaxy M94 from Hubble
              Image Credit & Copyright: [3]ESA/Hubble & [4]NASA

   Explanation: Why does this galaxy have a ring of bright blue stars?
   Beautiful island universe [5]Messier 94 lies a mere 15 million
   light-years distant in the northern constellation of the Hunting Dogs
   ([6]Canes Venatici). A popular target for [7]Earth-based astronomers,
   the face-on spiral galaxy is about 30,000 [8]light-years across, with
   spiral arms sweeping through the [9]outskirts of its broad disk. But
   this [10]Hubble Space Telescope field of view spans about 7,000
   light-years across [11]M94's central region. The [12]featured close-up
   highlights the galaxy's compact, bright nucleus, prominent inner
   [13]dust lanes, and the remarkable bluish ring of young massive stars.
   The ring stars are all likely less than 10 million years old,
   indicating that M94 is a [14]starburst galaxy that is experiencing an
   epoch of rapid star formation. The circular ripple of blue stars is
   likely a [15]wave propagating outward, having been [16]triggered by the
   gravity and rotation of a [17]oval matter distributions. Because M94 is
   relatively nearby, astronomers can better explore [18]details of its
   starburst ring.

     Astrophysicists: [19]Browse 2,000+ codes in the Astrophysics Source
                                Code Library
                     Tomorrow's picture: running mercury
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    Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell
                                 ([34]UMCP)
          NASA Official: Phillip Newman [35]Specific rights apply.
              [36]NASA Web Privacy Policy and Important Notices
                A service of: [37]ASD at [38]NASA / [39]GSFC
                           & [40]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/1912/M94_Hubble_1002.jpg
   3. http://www.spacetelescope.org/
   4. http://www.nasa.gov/
   5. https://en.wikipedia.org/wiki/Messier_94
   6. http://en.wikipedia.org/wiki/Canes_Venatici
   7. https://solarsystem.nasa.gov/planets/earth/overview/
   8. https://spaceplace.nasa.gov/light-year/en/
   9. https://apod.nasa.gov/apod/ap100114.html
  10. http://www.spacetelescope.org/images/potw1542a
  11. https://apod.nasa.gov/apod/ap150526.html
  12. https://www.spacetelescope.org/images/potw1542a/zoomable/
  13. https://apod.nasa.gov/apod/ap180322.html
  14. https://apod.nasa.gov/apod/ap191009.html
  15. https://en.wikipedia.org/wiki/Density_wave_theory
  16. https://ui.adsabs.harvard.edu/abs/2004ASSL..319..261K/abstract
  17. https://apod.nasa.gov/apod/ap181009.html
  18. https://ui.adsabs.harvard.edu/abs/2001AJ....121.1395W/abstract
  19. http://ascl.net/
  20. https://apod.nasa.gov/apod/ap191130.html
  21. https://apod.nasa.gov/apod/archivepix.html
  22. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  23. https://apod.nasa.gov/apod/lib/aptree.html
  24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  25. https://apod.nasa.gov/apod/calendar/allyears.html
  26. https://apod.nasa.gov/apod.rss
  27. https://apod.nasa.gov/apod/lib/edlinks.html
  28. https://apod.nasa.gov/apod/lib/about_apod.html
  29. http://asterisk.apod.com/discuss_apod.php?date=191201
  30. https://apod.nasa.gov/apod/ap191202.html
  31. http://www.phy.mtu.edu/faculty/Nemiroff.html
  32. http://www.phy.mtu.edu/
  33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  34. http://www.astro.umd.edu/
  35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  36. https://www.nasa.gov/about/highlights/HP_Privacy.html
  37. https://astrophysics.gsfc.nasa.gov/
  38. https://www.nasa.gov/
  39. https://www.nasa.gov/centers/goddard/
  40. http://www.mtu.edu/