                        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.

                              2024 December 23
    A star filled night sky is shown with aurora visible in blue, purple
   and green. The aurora could be perceived to be a spruce tree, or even a
        Christmas tree. Please see the explanation for more detailed
                                information.

                            Christmas Tree Aurora
                   Image Credit & Copyright: Jingyi Zhang

   Explanation: It was December and the sky lit up like a Christmas tree.
   Shimmering, the vivid green, blue, and purple auroral colors that
   formed the tree-like apparition were caused by high atmospheric oxygen
   and nitrogen reacting to a burst of incoming electrons. Collisions
   caused the orbital electrons of atoms and molecules to jump into
   excited energy states and emit visible light when returning to their
   normal state. The featured image was captured in Djúpivogur, Iceland
   during the last month of 2023. Our Sun is currently in its most
   energetic phase of its 11-year cycle, with its high number of active
   regions and sunspots likely to last into next year. Of course, the Sun
   has been near solar maximum during this entire year, with its outbursts
   sometimes resulting in spectacular Earthly auroras.

             Image Processors: Take NASA's Astrophoto Challenge
                        Tomorrow's picture: star tree
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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.

