                APOD: 2017 July 29 - Aurora Slathers up the Sky

                         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 July 29
                                      [2]
                          Aurora Slathers up the Sky
        Image Credit: Jack Fischer [3] , Expedition 52 [4] , NASA [5]

Explanation: Like salsa verde on your favorite burrito, a green aurora
slathers up the sky [6]  in this June 25 snapshot from the International Space
Station. About 400 kilometers (250 miles) above Earth, the orbiting station is
itself within the upper realm [7]  of the auroral displays. Aurorae have the
signature colors [8]  of excited molecules and atoms at the low densities
found at extreme altitudes. Emission from atomic oxygen dominates this view.
The tantalizing glow [9] is green at lower altitudes, but rarer reddish bands
extend above the space station's horizon. The orbital scene [10] was captured
while passing over a point south and east of Australia, with stars above the
horizon at the right belonging to the constellation Canis Major [11] , Orion's
big dog. Sirius [12] , alpha star of Canis Major, is the brightest star near
the Earth's limb.

                  Tomorrow's picture: end of the world [13]

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    Authors & editors: Robert Nemiroff [25] (MTU [26] ) & Jerry Bonnell [27]
                                  (UMCP [28] )
          NASA Official:  Phillip Newman Specific rights apply [29] .
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                           & Michigan Tech. U. [34]
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Site notes:
  [1] archivepix.html
  [2] image/1707/aurora_iss052e007857.jpg
  [3] https://twitter.com/Astro2fish/
  [4] https://www.nasa.gov/mission_pages/station/expeditions/
expedition52/index.html
  [5] http://www.nasa.gov
  [6] https://twitter.com/Astro2fish/status/884886605407727616
  [7] http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/
Christina%20Shaw/AuroraColors.html
  [8] http://www.webexhibits.org/causesofcolor/4D.html
  [9] https://twitter.com/Astro2fish/status/889198201236008960
  [10] https://eol.jsc.nasa.gov/SearchPhotos/
photo.pl?mission=ISS052&roll=E&frame=7857
  [11] http://www.hawastsoc.org/deepsky/cma/index.html
  [12] http://stars.astro.illinois.edu/sow/sirius.html
  [13] ap170730.html
  [14] ap170728.html
  [15] archivepix.html
  [16] lib/apsubmit2015.html
  [17] lib/aptree.html
  [18] http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [19] calendar/allyears.html
  [20] /apod.rss
  [21] lib/edlinks.html
  [22] lib/about_apod.html
  [23] http://asterisk.apod.com/discuss_apod.php?date=170729
  [24] ap170730.html
  [25] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [26] http://www.phy.mtu.edu/
  [27] http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [28] http://www.astro.umd.edu/
  [29] lib/about_apod.html#srapply
  [30] http://www.nasa.gov/about/highlights/HP_Privacy.html
  [31] http://astrophysics.gsfc.nasa.gov/
  [32] http://www.nasa.gov/
  [33] http://www.nasa.gov/centers/goddard/
  [34] http://www.mtu.edu/
