                        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.

                                2022 April 4

                        A Vortex Aurora over Iceland
                 Image Credit & Copyright: Christophe Suarez

   Explanation: No, the car was not in danger of being vacuumed into space
   by the big sky vortex. For one reason, the vortex was really an aurora,
   and since auroras are created by particles striking the Earth from
   space, they do not create a vacuum. This rapidly developing auroral
   display was caused by a Coronal Mass Ejection from the Sun that passed
   by the Earth closely enough to cause a ripple in Earth's magnetosphere.
   The upper red parts of the aurora occur over 250 kilometers high with
   its red glow created by atmospheric atomic oxygen directly energized by
   incoming particles. The lower green parts of the aurora occur over 100
   kilometers high with its green glow created by atmospheric atomic
   oxygen energized indirectly by collisions with first-energized
   molecular nitrogen. Below 100 kilometers, there is little atomic
   oxygen, which is why auroras end abruptly. The concentric cylinders
   depict a dramatic auroral corona as seen from the side. The featured
   image was created from a single 3-second exposure taken in mid-March
   over Lake Myvatn in Iceland.

                      April is: Global Astronomy Month
                    Tomorrow's picture: california seven
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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.

