          APOD: 2017 August 12 - A Day in the Life of a Human Sundial

                         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 August 12
                A Day in the Life of a (mostly) Human Sundial
  Video Credit & Copyright [2] : Astronomie-AG, Progymnasium Rosenfeld [3] ,
                        Till Credner, AlltheSky.com [4]

Explanation: Have you ever wanted to be a gnomon? Of course, a gnomon is the
tall part of a sundial [5] that casts a shadow. The gnomon's shadow moves as
the Sun moves across the sky, indicating time by the shadow's position on the
dial face. So on July 19th [6] , the Astronomy Group of the Progymnasium
Rosenfeld created a human sundial, each participant patiently playing the role
of the gnomon for 10 minutes. In this timelapse video of their temporal voyage
[7]  of discovery [8] , one image was taken every 20 seconds from 8 am until 4
pm Central European Summer Time. Drawn on the ground are the dial hour marks
calculated to show the local time for that specific date. Behind, the tower
clock offers a time check. Can you find the local time of solar noon? (Hint:
At solar noon the Sun is on the meridan [9] .) The persistent group plans a
repetition of the human sundial performance next winter to compare the length
of the day and the altitude of the Sun.

                  Tomorrow's picture: miasma of plasma [10]

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    Authors & editors: Robert Nemiroff [22] (MTU [23] ) & Jerry Bonnell [24]
                                  (UMCP [25] )
          NASA Official:  Phillip Newman Specific rights apply [26] .
              NASA Web Privacy Policy and Important Notices [27]
              A service of: ASD [28]  at NASA [29]  / GSFC [30]
                           & Michigan Tech. U. [31]
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Site notes:
  [1] archivepix.html
  [2] lib/about_apod.html#srapply
  [3] http://www.pgrosenfeld.de
  [4] http://www.allthesky.com/
  [5] https://en.wikipedia.org/wiki/Sundial
  [6] http://www.theskyinmotion.com/index.html?sundial19jul17.html
  [7] ap031206.html
  [8] http://www.astrobio.net/mars/ interview-with-bill-nye-the-sundial-guy/
  [9] https://en.wikipedia.org/wiki/Meridian_(astronomy)
  [10] ap170813.html
  [11] ap170811.html
  [12] archivepix.html
  [13] lib/apsubmit2015.html
  [14] lib/aptree.html
  [15] http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [16] calendar/allyears.html
  [17] /apod.rss
  [18] lib/edlinks.html
  [19] lib/about_apod.html
  [20] http://asterisk.apod.com/discuss_apod.php?date=170812
  [21] ap170813.html
  [22] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [23] http://www.phy.mtu.edu/
  [24] http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [25] http://www.astro.umd.edu/
  [26] lib/about_apod.html#srapply
  [27] http://www.nasa.gov/about/highlights/HP_Privacy.html
  [28] http://astrophysics.gsfc.nasa.gov/
  [29] http://www.nasa.gov/
  [30] http://www.nasa.gov/centers/goddard/
  [31] http://www.mtu.edu/
