Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                              2020 September 26

                      Moon Pairs and the Synodic Month
               Image Credit & Copyright: Marcella Giulia Pace

   Explanation: Observe the Moon each night and its visible sunlit portion
   will gradually change. In phases progressing from New Moon to Full Moon
   to New Moon again, a lunar cycle or synodic month is completed in about
   29.5 days. They look full, but top left to bottom right these panels do
   show the range of lunar phases for a complete synodic month during
   August 2019 from Ragusa, Sicily, Italy, planet Earth. For this lunar
   cycle project the panels organize images of the lunar phases in pairs.
   Each individual image is paired with another image separated by about
   15 days, or approximately half a synodic month. As a result the
   opposite sunlit portions complete the lunar disk and the shadow line at
   the boundary of lunar night and day, the terminator, steadily marches
   across the Moon's familiar nearside. For extra credit, what lunar phase
   would you pair with the Moon tonight?

                      Tomorrow's picture: cloudy skies
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.


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