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 January 26
                                      [2]
                              The Umbra of Earth
              Image Credit & Copyright [3] : Antonio Finazzi [4]

Explanation: The dark, inner shadow of planet Earth is called the umbra [5] .
Shaped like a cone extending into space, it has a circular cross section most
easily seen during a lunar eclipse [6] . For example, on January 21 the Full
Moon slid [7]  across the northern half of Earth's umbral shadow, entertaining
[8] moonwatchers around much of the planet. In the total phase of the eclipse,
the Moon was completely within the umbra for 63 minutes. Recorded under clear,
dark skies from the hills near Chiuduno, Italy this composite eclipse image
uses successive [9] pictures from totality (center) and partial phases to
trace out a large part of the umbra's curved edge [10] . Reflecting sunlight
scattered by the atmosphere into Earth's shadow, the lunar surface appears
reddened during totality. But close to the umbra's edge, the limb of the
eclipsed Moon shows a distinct blue hue. The blue eclipsed [11] moonlight
originates as rays of sunlight pass through layers high in the upper
stratosphere, colored by ozone that scatters red light and transmits blue.

                     Tomorrow's picture: crossing the sky

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    Authors & editors: Robert Nemiroff [23] (MTU [24] ) & Jerry Bonnell [25]
                                  (UMCP [26] )
          NASA Official:  Phillip Newman Specific rights apply [27] .
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              A service of: ASD [29]  at NASA [30]  / GSFC [31]
                           & Michigan Tech. U. [32]
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Site notes:
  [1] archivepix.html
  [2] image/1901/LOmbradellaTerraFinazzi.jpg
  [3] lib/about_apod.html#srapply
  [4] mailto: a [dot] finazzi [dot] astronomy [at] sonic [dot] it
  [5] ap060909.html
  [6] https://solarsystem.nasa.gov/moons/earths-moo...
  [7] ap080220.html
  [8] ap190125.html
  [9] ap070901.html
  [10] ap080820.html
  [11] ap151003.html
  [12] ap190125.html
  [13] archivepix.html
  [14] lib/apsubmit2015.html
  [15] lib/aptree.html
  [16] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [17] calendar/allyears.html
  [18] /apod.rss
  [19] lib/edlinks.html
  [20] lib/about_apod.html
  [21] http://asterisk.apod.com/discuss_apod.php?dat...
  [22] ap190127.html
  [23] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [24] http://www.phy.mtu.edu/
  [25] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [26] http://www.astro.umd.edu/
  [27] lib/about_apod.html#srapply
  [28] https://www.nasa.gov/about/highlights/HP_Priv...
  [29] https://astrophysics.gsfc.nasa.gov/
  [30] https://www.nasa.gov/
  [31] https://www.nasa.gov/centers/goddard/
  [32] http://www.mtu.edu/

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