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 22
     [2]The Andromeda Galaxy is shown in great detail. Red nebulas, blue
   stars, and dark dust are all seen in a swirl around the galaxy's bright
      center. Please see the explanation for more detailed information.

                          M31: The Andromeda Galaxy
               Image Credit & Copyright: [3]Abdullah Al-Harbi

   Explanation: How far can you see? The most distant object easily
   visible to the unaided eye is M31, the great [4]Andromeda Galaxy, over
   two million [5]light-years away. Without a telescope, even this immense
   [6]spiral galaxy appears as an unremarkable, faint, [7]nebulous cloud
   in the [8]constellation Andromeda. But a bright white nucleus, dark
   winding dust lanes, luminous blue spiral arms, and bright red emission
   nebulas are recorded in [9]this stunning fifteen-hour telescopic
   digital mosaic of our [10]closest major galactic neighbor. But how do
   we know [11]this spiral nebula is really so far away? This question was
   central to the famous [12]Shapley-Curtis [13]debate [14]of 1920. M31's
   great distance was determined in the 1920s by [15]observations that
   resolved individual stars that [16]changed their brightness in a way
   that gave up their true distance. The result proved that [17]Andromeda
   is just like our [18]Milky Way Galaxy -- a conclusion making [19]the
   rest of the universe much [20]more vast than had ever been
   [21]previously imagined.

                       Tomorrow's picture: open space
     __________________________________________________________________

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    Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell
                                 ([36]UMCP)
          NASA Official: Phillip Newman [37]Specific rights apply.
              [38]NASA Web Privacy Policy and Important Notices
                A service of: [39]ASD at [40]NASA / [41]GSFC,
                         [42]NASA Science Activation
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2303/M31_Alharbi_4822.jpg
   3. https://www.instagram.com/a_alharbi97/
   4. https://en.wikipedia.org/wiki/Andromeda_Galaxy
   5. https://youtu.be/MX3PIkbTQwQ
   6. https://en.wikipedia.org/wiki/Spiral_galaxy
   7. https://apod.nasa.gov/apod/ap160322.html
   8. https://en.wikipedia.org/wiki/Andromeda_(constellation)
   9. https://www.instagram.com/p/CpsrUSHMJis/
  10. https://youtu.be/TijClV4uHIk
  11. https://apod.nasa.gov/apod/ap221024.html
  12. https://apod.nasa.gov/debate/debate20.html
  13. https://apod.nasa.gov/debate/debate.html
  14. https://apod.nasa.gov/debate/debate20.html
  15. https://apod.nasa.gov/apod/ap200426.html
  16. https://apod.nasa.gov/apod/ap110701.html
  17. https://apod.nasa.gov/apod/ap220807.html
  18. https://apod.nasa.gov/apod/ap180729.html
  19. https://apod.nasa.gov/apod/ap180508.html
  20. https://apod.nasa.gov/apod/ap200405.html
  21. https://i.pinimg.com/736x/17/e0/6c/17e06cb8ddaa2fc90b7a416c0d0349ef--pugs-on-the-beach.jpg
  22. https://apod.nasa.gov/apod/ap230321.html
  23. https://apod.nasa.gov/apod/archivepix.html
  24. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  25. https://apod.nasa.gov/apod/lib/aptree.html
  26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  27. https://apod.nasa.gov/apod/calendar/allyears.html
  28. https://apod.nasa.gov/apod.rss
  29. https://apod.nasa.gov/apod/lib/edlinks.html
  30. https://apod.nasa.gov/apod/lib/about_apod.html
  31. https://asterisk.apod.com/discuss_apod.php?date=230322
  32. https://apod.nasa.gov/apod/ap230323.html
  33. http://www.phy.mtu.edu/faculty/Nemiroff.html
  34. http://www.phy.mtu.edu/
  35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  36. http://www.astro.umd.edu/
  37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  38. https://www.nasa.gov/about/highlights/HP_Privacy.html
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. https://science.nasa.gov/learners
  43. http://www.mtu.edu/