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 June 7
    [2]A spiral galaxy is seen in the image center with a distinct purple
   hue. The galaxy features a bright inner ring, but even outside of that
      appears another large ring. The outer rings appears light brown.
      Foreground stars are visible throughout the image. Please see the
                 explanation for more detailed information.

                          M94: A Double Ring Galaxy
                 Image Credit & Copyright: [3]Brian Brennan

   Explanation: Most galaxies don't have any rings of stars and gas -- why
   does [4]M94 have two? First, [5]spiral galaxy M94 has an inner ring of
   newly formed stars surrounding its nucleus, giving it not only an
   [6]unusual appearance but also a strong interior glow. A [7]leading
   origin hypothesis holds that an elongated [8]knot of stars known as a
   [9]bar rotates in [10]M94 and has generated a burst of [11]star
   formation in this inner ring. [12]Observations have also revealed
   another ring, an outer ring, one that is more faint, different in
   color, not closed, and relatively complex. What caused this outer ring
   is currently unknown. M94, [13]pictured here, spans about 45,000
   [14]light years in total, lies about 15 million light years away, and
   can be seen with a [15]small telescope toward the [16]constellation of
   the Hunting Dogs ([17]Canes Venatici).

          More Availability: APOD now accessible via [18]Flipboard.
                       Tomorrow's picture: open space
     __________________________________________________________________

      [19]< | [20]Archive | [21]Submissions | [22]Index | [23]Search |
   [24]Calendar | [25]RSS | [26]Education | [27]About APOD | [28]Discuss |
                                    [29]>
     __________________________________________________________________

    Authors & editors: [30]Robert Nemiroff ([31]MTU) & [32]Jerry Bonnell
                                 ([33]UMCP)
          NASA Official: Phillip Newman [34]Specific rights apply.
              [35]NASA Web Privacy Policy and Important Notices
                A service of: [36]ASD at [37]NASA / [38]GSFC,
                         [39]NASA Science Activation
                           & [40]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2306/M94_Brennan_1565.jpg
   3. https://www.instagram.com/astrolips2000/
   4. http://en.wikipedia.org/wiki/Messier_94
   5. https://apod.nasa.gov/apod/spiral_galaxies.html
   6. https://www.rover.com/blog/wp-content/uploads/2017/02/pug-2648774_1920-960x540.jpg
   7. https://ui.adsabs.harvard.edu/abs/2001AJ....121.1395W/abstract
   8. http://en.wikipedia.org/wiki/Knot_(mathematics)#/media/File:Knot_table.svg
   9. https://apod.nasa.gov/apod/ap221016.html
  10. https://apod.nasa.gov/apod/ap100114.html
  11. https://universe.nasa.gov/stars/basics/
  12. https://ui.adsabs.harvard.edu/abs/2009ApJ...704..618T/abstract
  13. https://www.instagram.com/p/CscKadTpICu/
  14. http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html
  15. https://apod.nasa.gov/apod/ap011014.html
  16. https://spaceplace.nasa.gov/constellations/en/
  17. https://en.wikipedia.org/wiki/Canes_Venatici
  18. https://flipboard.com/@APOD_NASA
  19. https://apod.nasa.gov/apod/ap230606.html
  20. https://apod.nasa.gov/apod/archivepix.html
  21. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  22. https://apod.nasa.gov/apod/lib/aptree.html
  23. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  24. https://apod.nasa.gov/apod/calendar/allyears.html
  25. https://apod.nasa.gov/apod.rss
  26. https://apod.nasa.gov/apod/lib/edlinks.html
  27. https://apod.nasa.gov/apod/lib/about_apod.html
  28. https://asterisk.apod.com/discuss_apod.php?date=230607
  29. https://apod.nasa.gov/apod/ap230608.html
  30. http://www.phy.mtu.edu/faculty/Nemiroff.html
  31. http://www.phy.mtu.edu/
  32. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  33. http://www.astro.umd.edu/
  34. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  35. https://www.nasa.gov/about/highlights/HP_Privacy.html
  36. https://astrophysics.gsfc.nasa.gov/
  37. https://www.nasa.gov/
  38. https://www.nasa.gov/centers/goddard/
  39. https://science.nasa.gov/learners
  40. http://www.mtu.edu/