            APOD: 2017 December 26 - Grand Spiral Galaxy NGC 1232

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                               2017 December 26
                                      [2]
                        Grand Spiral Galaxy NGC 1232
          Image Credit: FORS [3] , 8.2-meter VLT Antu [4] , ESO [5]

Explanation: Galaxies [6]  are fascinating not only for what is visible, but
for what is invisible. Grand spiral [7]  galaxy NGC 1232 [8] , captured [9]
in detail by one of the Very Large Telescopes [10] , is a good example. The
visible is dominated by millions of bright stars [11]  and dark dust [12] ,
caught up in a gravitational swirl of spiral arms revolving about the center.
Open clusters [13]  containing bright blue stars can be seen sprinkled along
these spiral arms, while dark lanes [14] of dense interstellar dust [15] can
be seen sprinkled between them. Less visible [16] , but detectable, are
billions of dim normal stars and vast tracts of interstellar gas [17] ,
together wielding such high mass that they dominate the dynamics of the inner
galaxy [18] . Leading theories indicate that even greater amounts [19]  of
matter are invisible, in a form we don't yet know. This pervasive dark matter
[20]  is postulated, in part, to explain the motions [21] of the visible
matter in the outer regions of galaxies.

         Free APOD Lectures: January 5 in NYC & January 9 in DC [22]
                      Tomorrow's picture: dark horse [23]

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Site notes:
  [1] archivepix.html
  [2] image/1712/ngc1232b_vlt_3969.jpg
  [3] http://www.eso.org/sci/facilities/paranal/instruments/fors/
  [4] http://www.eso.org/projects/vlt/
  [5] http://www.eso.org/
  [6] http://www.astr.ua.edu/keel/galaxies/
  [7] ap961030.html
  [8] http://adsabs.harvard.edu/abs/1997AAS...191.8203B
  [9] https://www.eso.org/public/images/eso9845d/
  [10] ap000707.html
  [11] ap031227.html
  [12] ap030706.html
  [13] open_clusters.html
  [14] ap980116.html
  [15] ap001119.html
  [16]
https://files.ctctcdn.com/3a7f39ae001/aedd7697-f09f-4b3a-8f7b-256d0a0389bc.jpg
  [17] ap010113.html
  [18] http://asterisk.apod.com/viewtopic.php?f=24&t=18005
  [19] ap031231.html
  [20] http://chandra.harvard.edu/xray_astro/dark_matter.html
  [21] http://en.wikipedia.org/wiki/Dark_matter
  [22] http://asterisk.apod.com/viewtopic.php?f=28&t=37750
  [23] ap171227.html
  [24] ap171225.html
  [25] archivepix.html
  [26] lib/apsubmit2015.html
  [27] lib/aptree.html
  [28] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [29] calendar/allyears.html
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  [34] ap171227.html
  [35] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [36] http://www.phy.mtu.edu/
  [37] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
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