        APOD: 2018 May 22 - Craters and Shadows at the Lunar Terminator

                         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 May 22
                                      [2]
                 Craters and Shadows at the Lunar Terminator
                    Image Credit & Copyright: Talha Zia [3]

Explanation: Why does the right part of this image of the Moon stand out?
Shadows. The terminator [4]  line -- the line between light and dark -- occurs
in the featured image so that just over half the Moon [5] 's face is
illuminated by sunlight. The lunar surface appears different nearer the
terminator [6]  because there the Sun [7]  is nearer the horizon and therefore
causes shadows to become increasingly long [8] . These shadows make it easier
for us to discern structure [9] , giving us depth cues [10]  so that the
two-dimensional [11]  image, when dominated by shadows, appears almost
three-dimensional [12] . Therefore, as the Moon fades [13]  from light to
dark, shadows [14]  not only tell us the high from the low, but become
noticeable for increasingly shorter structures. For example, many craters
appear near the terminator because their height makes them easier to discern
there. The image was taken two weeks ago when the lunar phase [15]  was waning
gibbous [16] . The next full moon [17] , a Moon without shadows, will occur
one week from today.

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                  Tomorrow's picture: galaxies collide [22]

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Site notes:
  [1] archivepix.html
  [2] image/1805/TerminatorMoon_Zia_1176.jpg
  [3] mailto: talhazia .dot. petromer @at@ gmail .dot. com
  [4] https://en.wikipedia.org/wiki/Terminator_(solar)
  [5] https://solarsystem.nasa.gov/moons/earths-moon/overview/
  [6] ap150427.html
  [7] https://solarsystem.nasa.gov/solar-system/sun/in-depth/
  [8] ap180320.html
  [9] ap161210.html
  [10]
http://scienceblogs.com/mixingmemory/2007/11/19/cool-visual-illusions-the-powe/
  [11] https://en.wikipedia.org/wiki/Two-dimensional_space
  [12] https://en.wikipedia.org/wiki/Three-dimensional_space
  [13] ap120205.html
  [14] ap170717.html
  [15] https://www.youtube.com/watch?v=f4ZHdzl6ZWg
  [16]
https://bobmoler.files.wordpress.com/2017/02/
waxing-waning-moon_nasa-bill-dunford.png
  [17] ap180328.html
  [18] https://www.facebook.com/AstronomyPictureOfTheDay
  [19] https://plus.google.com/u/1/+AstronomyPictureOfTheDay
  [20] https://www.instagram.com/astronomypicturesdaily/
  [21] http://twitter.com/apod/
  [22] ap180523.html
  [23] ap180521.html
  [24] archivepix.html
  [25] lib/apsubmit2015.html
  [26] lib/aptree.html
  [27] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [28] calendar/allyears.html
  [29] /apod.rss
  [30] lib/edlinks.html
  [31] lib/about_apod.html
  [32] http://asterisk.apod.com/discuss_apod.php?date=180522
  [33] ap180523.html
  [34] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [35] http://www.phy.mtu.edu/
  [36] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [37] http://www.astro.umd.edu/
  [38] lib/about_apod.html#srapply
  [39] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [40] https://astrophysics.gsfc.nasa.gov/
  [41] https://www.nasa.gov/
  [42] https://www.nasa.gov/centers/goddard/
  [43] http://www.mtu.edu/
