                        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.

                                2021 June 19

                          Northern Summer Twilight
                  Image Credit & Copyright: Justin Anderson

   Explanation: Nights grow shorter and days grow longer as the summer
   solstice approaches in the north. Usually seen at high latitudes in
   summer months, noctilucent or night shining clouds begin to make their
   appearance. Drifting near the edge of space about 80 kilometers above
   the Earth's surface, these icy clouds were still reflecting the
   sunlight on June 14. Though the Sun was below the horizon as seen north
   of Forrest, Manitoba, Canada, they were caught in a single exposure of
   a near midnight twilight sky. Multiple exposures of the foreground
   track the lower altitude flash of fireflies, another fleeting
   apparition shining in the summer night.

                  Tomorrow's picture: the season's sunrise
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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