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.

                                 2019 March 6
                                      [2]
                         A February without Sunspots
    Images Credit & Copyright: Alan Friedman [3] (Averted Imagination [4] )

Explanation: Where have all the sunspots gone? Last month the total number of
spots that crossed our Sun was ... zero [5] . Well below of the long term
monthly average, the Sun's surface has become as unusually passive this solar
minimum [6]  just like it did 11 years ago during the last solar minimum [7] .
Such passivity is not just a visual spectacle [8] , it correlates with the Sun
[9] being slightly dimmer [10] , with holes [11]  in the Sun's corona [12]
being more stable, and with a reduced intensity in the outflowing solar wind
[13] . The reduced wind, in turn, cools and collapses Earth's outer atmosphere
[14]  (the thermosphere [15] ), causing reduced drag on many Earth-orbiting
satellites. Pictured in inverted black & white on the left, the Sun's busy
surface is shown near solar maximum [16]  in 2012, in contrast to the image on
the right, which shows the Sun's surface last August, already without spots
(for a few days), as solar minimum [17]  was setting in. Effects of this
unusually static solar minimum are being studied [18] .

                     Tomorrow's picture: cosmic jellyfish

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    Authors & editors: Robert Nemiroff [30] (MTU [31] ) & Jerry Bonnell [32]
                                  (UMCP [33] )
          NASA Official:  Phillip Newman Specific rights apply [34] .
              NASA Web Privacy Policy and Important Notices [35]
              A service of: ASD [36]  at NASA [37]  / GSFC [38]
                           & Michigan Tech. U. [39]
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Site notes:
  [1] archivepix.html
  [2] image/1903/SunMaxMin_Friedman_1733.jpg
  [3] mailto: alan at greatarrow dot com
  [4] http://www.avertedimagination.com/
  [5] http://spaceweather.com/archive.php?view=1&da...
  [6]
https://science.nasa.gov/science-news/news-ar...
  [7] https://www.nasa.gov/topics/solarsystem/featu...
  [8] https://media.tenor.com/images/dc1bbc8e86816a...
  [9] https://solarsystem.nasa.gov/solar-system/sun...
  [10] https://spaceweatherarchive.com/2017/12/17/th...
  [11] ap100828.html
  [12] ap170920.html
  [13] ap000318.html
  [14]
https://science.nasa.gov/science-news/science...
  [15] https://spaceplace.nasa.gov/thermosphere/en/
  [16] ap170219.html
  [17] https://en.wikipedia.org/wiki/Solar_minimum
  [18] http://parkersolarprobe.jhuapl.edu/index.php#...
  [19] ap190305.html
  [20] archivepix.html
  [21] lib/apsubmit2015.html
  [22] lib/aptree.html
  [23] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [24] calendar/allyears.html
  [25] /apod.rss
  [26] lib/edlinks.html
  [27] lib/about_apod.html
  [28] http://asterisk.apod.com/discuss_apod.php?dat...
  [29] ap190307.html
  [30] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [31] http://www.phy.mtu.edu/
  [32] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [33] http://www.astro.umd.edu/
  [34] lib/about_apod.html#srapply
  [35] https://www.nasa.gov/about/highlights/HP_Priv...
  [36] https://astrophysics.gsfc.nasa.gov/
  [37] https://www.nasa.gov/
  [38] https://www.nasa.gov/centers/goddard/
  [39] http://www.mtu.edu/

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