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 August 20
                                      [2]
                      Active Prominences on a Quiet Sun
  Image Credit & Copyright [3] : Alan Friedman [4] (Averted Imagination [5] )

Explanation: Why is the Sun so quiet? As the Sun [6]  enters into a period of
time known as a Solar Minimum [7] , it is, as expected, showing fewer sunspots
[8]  and active regions [9]  than usual. The quietness is somewhat unsettling
[10] , though, as so far this year, most days show no sunspots at all. In
contrast, from 2011 - 2015, during Solar Maximum [11] , the Sun displayed
spots just about every day. Maxima and minima occur on an 11-year cycle [12] ,
with the last Solar Minimum [13] being the most quiet in a century. Will this
current Solar Minimum go even deeper [14] ? Even though the Sun's activity
[15]  affects the Earth and its surroundings, no one knows for sure what the
Sun will do next [16] , and the physics behind the processes remain an active
topic of research [17] . The featured image [18]  was taken three weeks ago
[19]  and shows that our Sun is busy even on a quiet day. Prominences [20]  of
hot plasma [21] , some larger than the Earth [22] , dance continually and are
most easily visible over the edge.

                     Tomorrow's picture: elements of soul

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    Authors & editors: Robert Nemiroff [34] (MTU [35] ) & Jerry Bonnell [36]
                                  (UMCP [37] )
          NASA Official:  Phillip Newman Specific rights apply [38] .
              NASA Web Privacy Policy and Important Notices [39]
              A service of: ASD [40]  at NASA [41]  / GSFC [42]
                           & Michigan Tech. U. [43]
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Site notes:
  [1] archivepix.html
  [2] image/1808/SolarProminences_Friedman_821.jpg
  [3] lib/about_apod.html#srapply
  [4] mailto: alan at greatarrow dot com
  [5] http://www.avertedimagination.com/
  [6] https://solarsystem.nasa.gov/solar-system/sun...
  [7]
https://science.nasa.gov/science-news/news-ar...
  [8] ap020718.html
  [9] ap150629.html
  [10]
https://www.barkbusters.co.uk/images/articles...
7a4120f095480e9f2a2ad2a165d90313.jpg
  [11] ap140312.html
  [12] ap071203.html
  [13]
https://science.nasa.gov/science-news/science...
01apr_deepsolarminimum/
  [14]
https://www.universetoday.com/139189/
are-we-headed-towards-another-deep-solar-minimum/
  [15] https://solarscience.msfc.nasa.gov/images/Cyc...
  [16]
https://www.swpc.noaa.gov/news/
solar-cycle-24-status-and-solar-cycle-25-upcoming-forecast
  [17] http://adsabs.harvard.edu/abs/2015LRSP...12.....
  [18] http://www.avertedimagination.com/img_pages/a...
  [19] http://www.spaceweather.com/archive.php?view=...
  [20] ap140720.html
  [21] https://en.wikipedia.org/wiki/Plasma_(physics...
  [22] ap160919.html
  [23] ap180819.html
  [24] archivepix.html
  [25] lib/apsubmit2015.html
  [26] lib/aptree.html
  [27] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [28] calendar/allyears.html
  [29] /apod.rss
  [30] lib/edlinks.html
  [31] lib/about_apod.html
  [32] http://asterisk.apod.com/discuss_apod.php?dat...
  [33] ap180821.html
  [34] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [35] http://www.phy.mtu.edu/
  [36] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [37] http://www.astro.umd.edu/
  [38] lib/about_apod.html#srapply
  [39] https://www.nasa.gov/about/highlights/HP_Priv...
  [40] https://astrophysics.gsfc.nasa.gov/
  [41] https://www.nasa.gov/
  [42] https://www.nasa.gov/centers/goddard/
  [43] http://www.mtu.edu/

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