                        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.

                                2023 April 17
   A large red ring is seen high above a landscape that has sparse clouds
   and a foreground building. Please see the explanation for more detailed
                                information.

                         ELVES Lightning over Italy
                  Image Credit & Copyright: Valter Binotto

   Explanation: What's that red ring in the sky? Lightning. The most
   commonly seen type of lightning involves flashes of bright white light
   between clouds. Over the past 50 years, though, other types of
   upper-atmospheric lightning have been confirmed, including red sprites
   and blue jets. Less well known and harder to photograph is a different
   type of upper atmospheric lightning known as ELVES. ELVES are thought
   to be created when an electromagnetic pulse shoots upward from charged
   clouds and impacts the ionosphere, causing nitrogen molecules to glow.
   The red ELVES ring pictured had a radius of about 350 km and was
   captured in late March about 100 kilometers above Ancona, Italy. Years
   of experience and ultra-fast photography were used to capture this
   ELVES -- which lasted only about 0.001 second.

                Tomorrow's picture: moon shadow, moon shadow
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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.

