              APOD: 2017 December 5 - A Horizon with Blue and Red

                         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 5
                                      [2]
                         A Horizon with Blue and Red
 Image Credit & Copyright: Sergio Montúfar [3] ( Planetario Ciudad de La Plata
                                    [4] )

Explanation: What's happening on the horizon? The horizon itself, past a
spinach [5]  field in Guatemala [6] , shows not only trees but a large
volcano: the Volcán de Fuego [7]  (Volcano of Fire). The red glow at the top
of the volcano is hot lava. But your eye may also be drawn [8]  to the blue
circle above the horizon on the left. This circle surrounds the Moon [9]  and,
together with other colors, is called a corona [10] . A corona [11]  is caused
by diffraction [12]  of light -- here moonlight -- by small water droplets in
the Earth's intervening atmosphere [13] . A break in the clouds on the right
shows stars and even the planet Saturn [14]  far beyond the volcano. Although
Volcán de Fuego [15]  frequently undergoes low-level activity, the
astrophotographer considered himself lucky to capture the scene just during an
explosive eruption [16]  in late September.

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                                    [20]
                      Tomorrow's picture: dust evil [21]

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    Authors & editors: Robert Nemiroff [33] (MTU [34] ) & Jerry Bonnell [35]
                                  (UMCP [36] )
          NASA Official:  Phillip Newman Specific rights apply [37] .
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                           & Michigan Tech. U. [42]
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Site notes:
  [1] archivepix.html
  [2] image/1712/BlueMoonRedVolcano_Montufar_4096.jpg
  [3] https://www.facebook.com/MilkyWayAddicted/info?tab=page_info
  [4] https://www.facebook.com/PlanetarioLaPlata
  [5] https://en.wikipedia.org/wiki/Spinach
  [6] https://en.wikipedia.org/wiki/Guatemala
  [7] https://en.wikipedia.org/wiki/Volc%C3%A1n_de_Fuego
  [8]
http://www.commentsyard.com/wp-content/uploads/2015/06/
All-Cats-Looking-Up-540x338.jpg
  [9] https://solarsystem.nasa.gov/planets/moon
  [10] ap150615.html
  [11] ap160111.html
  [12] http://www.atoptics.co.uk/droplets/corform.htm
  [13]
https://www.nasa.gov/sites/default/files/images/
463940main_atmosphere-layers2_full.jpg
  [14] ap170829.html
  [15] https://www.youtube.com/watch?v=QiYM4P-I4io
  [16] ap150311.html
  [17] https://www.facebook.com/AstronomyPictureOfTheDay
  [18] https://plus.google.com/u/1/+AstronomyPictureOfTheDay
  [19] https://www.instagram.com/astronomypicturesdaily/
  [20] http://twitter.com/apod/
  [21] ap171206.html
  [22] ap171204.html
  [23] archivepix.html
  [24] lib/apsubmit2015.html
  [25] lib/aptree.html
  [26] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [27] calendar/allyears.html
  [28] /apod.rss
  [29] lib/edlinks.html
  [30] lib/about_apod.html
  [31] http://asterisk.apod.com/discuss_apod.php?date=171205
  [32] ap171206.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] 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] http://www.mtu.edu/
