                        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.

                                2026 June 25
   A landscape with an open horizon shows sunset color and coverging rays
                                  of light.

                      Anticrepuscular Rays over Sicily
               Image Credit & Copyright: Marcella Giulia Pace
             Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)

   Explanation: The Sun has just set... in the opposite side of the sky.
   Pictured here are anticrepuscular rays apparently converging in the
   east in this image of the limestone plateau in the heart of the
   Hyblaean Mountains of southeastern Sicily, in Italy. How were these
   anticrepuscular rays formed, if the Sun wasn't there? After the Sun set
   (in the west, as usual) its light still illuminated a cloud higher up
   in the sky. Partially blocked by the cloud, the sunlight produced
   patterns of light and shadow, crossing the sky in parallel lines.
   Perspective makes it look like they converge in the east, in the same
   way that train tracks appear to meet in the distance. This effect can
   also happen at sunrise, only the directions are exchanged. In rare
   cases, both crepuscular and anticrepuscular rays can be seen at the
   same time.

                      Tomorrow's picture: What's next?
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

