          APOD: 2018 March 7 - Arcs, Jets, and Shocks near NGC 1999

                         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 March 7
                                      [2]
                    Arcs, Jets, and Shocks near NGC 1999
                  Image Credit & Copyright: Mark Hanson [3]

Explanation: This tantalizing array of nebulas and stars can be found about
two degrees south of the famous star-forming [4]  Orion Nebula. The region
abounds [5]  with energetic young stars producing jets and outflows that push
through the surrounding material at speeds of hundreds of kilometers per
second. The interaction [6]  creates luminous shock waves known as Herbig-Haro
[7]  (HH) objects. For example, the graceful, flowing arc just right of center
is cataloged as HH 222 [8] , also called the Waterfall Nebula [9] . Seen below
the Waterfall, HH 401 has a distinctive cone shape. The bright bluish nebula
below and left of center is NGC 1999 [10] , a dusty cloud reflecting light
from an embedded variable star. The entire cosmic vista [11]  spans over 30
light-years, near the edge of the Orion Molecular Cloud [12] Complex [13] some
1,500 light-years distant.

Open Science: Browse 1,600+ codes in the Astrophysics Source Code Library [14]

                      Tomorrow's picture: open space [15]

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Site notes:
  [1] archivepix.html
  [2] image/1803/NGC1999_Hanson_3847.jpg
  [3] https://www.hansonastronomy.com/bio/
  [4]
https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve
  [5] http://www.noao.edu/outreach/latest/ngc1999about.html
  [6] ap070811.html
  [7] https://en.wikipedia.org/wiki/Herbig%E2%80%93Haro_object
  [8] ap111024.html
  [9] https://danspace77.com/2016/06/15/the-water-fall-nebula-zoom/
  [10] ap131128.html
  [11] https://www.hansonastronomy.com/ngc-1999
  [12] https://en.wikipedia.org/wiki/Orion_Molecular_Cloud_Complex
  [13] http://arxiv.org/abs/astro-ph/0609171
  [14] http://ascl.net/code/all
  [15] ap180308.html
  [16] ap180306.html
  [17] archivepix.html
  [18] lib/apsubmit2015.html
  [19] lib/aptree.html
  [20] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [21] calendar/allyears.html
  [22] /apod.rss
  [23] lib/edlinks.html
  [24] lib/about_apod.html
  [25] http://asterisk.apod.com/discuss_apod.php?date=180307
  [26] ap180308.html
  [27] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [28] http://www.phy.mtu.edu/
  [29] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [30] http://www.astro.umd.edu/
  [31] lib/about_apod.html#srapply
  [32] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [33] https://astrophysics.gsfc.nasa.gov/
  [34] https://www.nasa.gov/
  [35] https://www.nasa.gov/centers/goddard/
  [36] http://www.mtu.edu/
