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 August 24

                              Crescent Moon HDR
       Image Credit & Copyright: Miguel Claro (TWAN, Dark Sky Alqueva)

   Explanation: How come the crescent Moon doesn't look like this? For one
   reason, because your eyes can't simultaneously discern bright and dark
   regions like this. Called earthshine or the da Vinci glow, the unlit
   part of a crescent Moon is visible but usually hard to see because it
   is much dimmer than the sunlit arc. In our digital age, however, the
   differences in brightness can be artificially reduced. The featured
   image is actually a digital composite of 15 short exposures of the
   bright crescent, and 14 longer exposures of the dim remainder. The
   origin of the da Vinci glow, as explained by Leonardo da Vinci about
   510 years ago, is sunlight reflected first by the Earth to the Moon,
   and then back from the Moon to the Earth.

                   Tomorrow's picture: around a black hole
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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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