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 May 31

                             Aurora over Sweden
                    Image Credit & Copyright: Göran Strand

   Explanation: It was bright and green and stretched across the sky. This
   striking aurora display was captured in 2016 just outside of Östersund,
   Sweden. Six photographic fields were merged to create the featured
   panorama spanning almost 180 degrees. Particularly striking aspects of
   this aurora include its sweeping arc-like shape and its stark
   definition. Lake Storsjön is seen in the foreground, while several
   familiar constellations and the star Polaris are visible through the
   aurora, far in the background. Coincidently, the aurora appears to
   avoid the Moon visible on the lower left. The aurora appeared a day
   after a large hole opened in the Sun's corona allowing particularly
   energetic particles to flow out into the Solar System. The green color
   of the aurora is caused by oxygen atoms recombining with ambient
   electrons high in the Earth's atmosphere.

                       Tomorrow's picture: red lagoon
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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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