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 July 4

                          Meeting in the Mesosphere
       Image Credit & Copyright: Stephane Vetter (TWAN, Nuits sacrees)

   Explanation: A sensitive video camera on a summit of the Vosges
   mountains in France captured these surprising fireworks above a distant
   horizon on June 26. Generated over intense thunderstorms, this one
   about 260 kilometers away, the brief and mysterious flashes have come
   to be known as red sprites. The transient luminous events are caused by
   electrical breakdown at altitudes of 50 to 100 kilometers. That puts
   them in the mesophere, the coldest layer of planet Earth's atmosphere.
   The glow beneath the sprites is from more familiar lighting though,
   below the storm clouds. But on the right, the video frames have
   captured another summertime apparition from the mesophere. The silvery
   veins of light are polar mesospheric clouds. Also known as noctilucent
   or night shining clouds, the icy clouds still reflect the sunlight when
   the Sun is below the horizon.

                    Tomorrow's picture: Saturn six-sided
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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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