                        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.

                                2025 July 11

                             The Veins of Heaven
           Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN)

   Explanation: Transfusing sunlight as the sky grew darker, this
   exceptional display of noctilucent clouds was captured on July 10,
   reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden.
   From the edge of space, about 80 kilometers above Earth's surface, the
   icy clouds themselves still reflect sunlight, even though the Sun is
   below the horizon as seen from the ground. Usually spotted at high
   latitudes in summer months, the night shining clouds have made a strong
   showing so far during the short northern summer nights. Also known as
   polar mesopheric clouds they are understood to form as water vapor
   driven into the cold upper atmosphere condenses on the fine dust
   particles supplied by disintegrating meteors or volcanic ash.

                      Tomorrow's picture: light-weekend
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                           NASA Science Activation
                             & Michigan Tech. U.

