            APOD: 2017 September 7 - The Flash Spectrum of the Sun

                         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 September 7
                                      [2]
                        The Flash Spectrum of the Sun
  Image Credit & Copyright [3] : Yujing Qin  [4] (University of Arizona [5] )

Explanation: In clear Madras, Oregon skies, this colorful eclipse composite
captured the elusive chromospheric [6]  or flash spectrum of the Sun. Only
three exposures, made on August 21 with telephoto lens and diffraction
grating, are aligned in the frame. Directly imaged at the far left, the Sun's
diamond ring-like [7]  appearance at the beginning and end of totality
brackets a silhouette of the lunar disk at maximum eclipse. Spread by the
diffraction [8]  grating into the spectrum of colors toward the right, the
Sun's photospheric spectrum [9] traces the two continuous streaks. They
correspond to the diamond ring glimpses of the Sun's normally overwhelming
disk. But individual eclipse images also appear at each wavelength of light
emitted by atoms along the thin, fleeting arcs of the solar chromosphere [10]
. The brightest images, or strongest chromospheric emission [11] , are due to
Hydrogen atoms. Red hydrogen alpha emission is at the far right with blue and
purple hydrogen series emission to the left. In between, the brightest yellow
emission is caused by atoms of Helium, an element only first discovered [12]
in the flash spectrum of the Sun [13] .

                Tomorrow's picture: a great gig in the sky [14]

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    Authors & editors: Robert Nemiroff [26] (MTU [27] ) & Jerry Bonnell [28]
                                  (UMCP [29] )
          NASA Official:  Phillip Newman Specific rights apply [30] .
              NASA Web Privacy Policy and Important Notices [31]
              A service of: ASD [32]  at NASA [33]  / GSFC [34]
                           & Michigan Tech. U. [35]
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Site notes:
  [1] archivepix.html
  [2] image/1709/DSC00198SpecSunCropQin.jpg
  [3] lib/about_apod.html#srapply
  [4] mailto: qinyj [@] email [dot] arizona [dot] edu
  [5] https://www.as.arizona.edu/
  [6] https://eclipse2017.nasa.gov/chromosphere
  [7] ap170825.html
  [8] http://micro.magnet.fsu.edu/primer/lightandcolor/ diffractionhome.html
  [9] ap131002.html
  [10] ap131108.html
  [11] http://dailysolar.weebly.com/uploads/3/4/8/5/3485153/ 9810884.jpg
  [12] ap980516.html
  [13] http://www.phys.vt.edu/~heremans/Astrolab1156/Readings/ flash.html
  [14] ap170908.html
  [15] ap170906.html
  [16] archivepix.html
  [17] lib/apsubmit2015.html
  [18] lib/aptree.html
  [19] http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [20] calendar/allyears.html
  [21] /apod.rss
  [22] lib/edlinks.html
  [23] lib/about_apod.html
  [24] http://asterisk.apod.com/discuss_apod.php?date=170907
  [25] ap170908.html
  [26] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [27] http://www.phy.mtu.edu/
  [28] http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [29] http://www.astro.umd.edu/
  [30] lib/about_apod.html#srapply
  [31] http://www.nasa.gov/about/highlights/HP_Privacy.html
  [32] http://astrophysics.gsfc.nasa.gov/
  [33] http://www.nasa.gov/
  [34] http://www.nasa.gov/centers/goddard/
  [35] http://www.mtu.edu/
