        APOD: 2017 November 10 - Williamina Fleming's Triangular Wisp

                         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 November 10
                                      [2]
                    Williamina Fleming's Triangular Wisp
                Image Credit & Copyright [3] : Sara Wager [4]

Explanation: Chaotic in appearance [5] , these tangled filaments of shocked,
glowing gas are spread across planet Earth's sky toward the constellation of
Cygnus as part of the Veil Nebula [6] . The Veil Nebula itself is a large
supernova remnant [7] , an expanding cloud born of the death explosion of a
massive star. Light from the original supernova explosion likely reached Earth
over 5,000 years ago. Blasted out [8] in the cataclysmic event, the
interstellar shock waves plow through space sweeping up and exciting
interstellar material. The glowing filaments are really more like long ripples
in a sheet seen almost edge on, remarkably well separated into the glow of
ionized hydrogen atoms shown in red and oxygen in blue hues. Also known as the
Cygnus Loop, the Veil Nebula now spans [9] nearly 3 degrees or about 6 times
the diameter of the full Moon. While that translates to over 70 light-years at
its estimated distance of 1,500 light-years, this field of view spans less
than one third that distance. Often identified as Pickering's Triangle for a
director of Harvard College Observatory, the complex of filaments is cataloged
as NGC 6979. It is also known for its discoverer, astronomer Williamina
Fleming [10] , as Fleming's Triangular Wisp [11] .

                    Tomorrow's picture: light-weekend [12]

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Site notes:
  [1] archivepix.html
  [2] image/1711/NGC6979_wager.jpg
  [3] lib/about_apod.html#srapply
  [4] http://www.swagastro.com/
  [5] https://www.swagastro.com/pickerings-triangle.html
  [6] http://spider.seds.org/spider/Misc/veil.html
  [7] http://chandra.harvard.edu/xray_sources/ supernovas.html
  [8] http://arxiv.org/abs/astro-ph/0104243
  [9] http://archive.stsci.edu/fuse/scisumm/ sci_cyglpstar.html
  [10] http://ocp.hul.harvard.edu/ww/fleming.html
  [11] http://www.davidcortner.com/slowblog/20161113.php
  [12] ap171111.html
  [13] ap171109.html
  [14] archivepix.html
  [15] lib/apsubmit2015.html
  [16] lib/aptree.html
  [17] http://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=171110
  [23] ap171111.html
  [24] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [25] http://www.phy.mtu.edu/
  [26] http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [27] http://www.astro.umd.edu/
  [28] lib/about_apod.html#srapply
  [29] http://www.nasa.gov/about/highlights/HP_Privacy.html
  [30] http://astrophysics.gsfc.nasa.gov/
  [31] http://www.nasa.gov/
  [32] http://www.nasa.gov/centers/goddard/
  [33] http://www.mtu.edu/
