Astronomy Picture of the Day

                         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.

                               2018 December 31
                                      [2]
                            The Witch Head Nebula
  Image Credit & Copyright: Digitized Sky Survey [3]  (POSS II); Processing:
                              Utkarsh Mishra [4]

Explanation: Double, double toil and trouble; [5] Fire burn, and cauldron
bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A
frighteningly shaped reflection nebula [6] , this cosmic crone is about 800
light-years away though. Its malevolent visage seems to glare toward nearby
bright star Rigel in Orion [7] , just off the right edge of this frame. More
formally known as IC 2118, the interstellar cloud [8]  of dust and gas is
nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In
this composite portrait [9] , the nebula's color is caused not only by the
star's intense bluish light but because the dust grains scatter blue light
[10]  more efficiently than red. The same physical process causes Earth's
daytime sky to appear blue [11] , although the scatterers in planet Earth's
atmosphere are molecules of nitrogen and oxygen.

                 Free Download: 2019 APOD Calendar (v5) [12]
                        Tomorrow's picture: galaxy hat

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    Authors & editors: Robert Nemiroff [24] (MTU [25] ) & Jerry Bonnell [26]
                                  (UMCP [27] )
          NASA Official:  Phillip Newman Specific rights apply [28] .
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              A service of: ASD [30]  at NASA [31]  / GSFC [32]
                           & Michigan Tech. U. [33]
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Site notes:
  [1] archivepix.html
  [2] image/1812/WitchHeadNebula_Mishra_2725.jpg
  [3] http://archive.stsci.edu/dss/copyright.html
  [4] https://www.flickr.com/photos/163350986@N06/
  [5] http://www.potw.org/archive/potw283.html
  [6] ap011228.html
  [7] ap150316.html
  [8] http://arxiv.org/abs/1007.0241
  [9]
https://www.flickr.com/photos/163350986@N06/45335453644/in/dateposted-public
  [10] http://leo.astronomy.cz/mix/mix.html
  [11] http://math.ucr.edu/home/baez/physics/General/ BlueSky/blue_sky.html
  [12] https://apod.nasa.gov/apod/image/1812/ApodCalendar2019v5_Dave.pdf
  [13] ap181230.html
  [14] archivepix.html
  [15] lib/apsubmit2015.html
  [16] lib/aptree.html
  [17] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [18] calendar/allyears.html
  [19] /apod.rss
  [20] lib/edlinks.html
  [21] lib/about_apod.html
  [22] http://asterisk.apod.com/discuss_apod.php?date=181231
  [23] ap190101.html
  [24] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [25] http://www.phy.mtu.edu/
  [26] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [27] http://www.astro.umd.edu/
  [28] lib/about_apod.html#srapply
  [29] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [30] https://astrophysics.gsfc.nasa.gov/
  [31] https://www.nasa.gov/
  [32] https://www.nasa.gov/centers/goddard/
  [33] http://www.mtu.edu/

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