                        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 July 15
    Lightning spreads like roots from a tree up into the atmosphere from
   the top of a cloud. Stars are scattered across the night sky above and
                    the desert sits below the cloud deck.

                      Red Sprites in the Tatacoa Desert
                   Image Credit & Copyright: Mario Vargas
         Text: Keighley Rockcliffe (NASA GSFC, UMBC CSST, CRESST II)

   Explanation: Is there an angry Sith using force lightning in the
   Tatacoa Desert? This is not science fiction, but a red sprite with
   multiple streamers! Ordinary lightning occurs when thundercloud
   particles collide, lose their electrons, and build up negative charge
   at the cloud bottom. The cloud’s negative charge repels negative charge
   deeper into the Earth, leaving Earth’s surface positively charged. The
   opposite charges attract, reaching towards each other and superheating
   the air into a white strike of plasma. Red sprites are millisecond
   events triggered by positive cloud-to-ground lightning. They extend up
   into the mesosphere where the air is too thin for thunder. Their red
   glow comes from heated molecular nitrogen. There are several potential
   causes for red sprites, including that the preceding positive lightning
   exposes the negatively charged cloud core to the positively charged
   upper atmosphere, allowing those charges to connect. NASA’s Juno has
   observed sprites on Jupiter, indicating that sprites occur on other
   planets!

            Tomorrow's picture: a galaxy bursting with excitement
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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