                        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 October 22
   A landscape is pictured with snow and a line of evergreen trees. In the
     sky is a field of stars but also notable green aurora. The largest
     aurora appears similar in form to a Halloween ghost, Please see the
                 explanation for more detailed information.

                          Ghost Aurora over Canada
               Image Credit & Copyright: Yuichi Takasaka, TWAN

   Explanation: What does this aurora look like to you? While braving the
   cold to watch the skies above northern Canada early one morning in
   2013, a most unusual aurora appeared. The aurora definitely appeared to
   be shaped like something, but what? Two ghostly possibilities recorded
   by the astrophotographer were "witch" and "goddess of dawn", but please
   feel free to suggest your own Halloween-enhanced impressions.
   Regardless of fantastical pareidolic interpretations, the pictured
   aurora had a typical green color and was surely caused by the
   scientifically commonplace action of high-energy particles from space
   interacting with oxygen in Earth's upper atmosphere. In the image
   foreground, at the bottom, is a frozen Alexandra Falls, while evergreen
   trees cross the middle.

   Help Wanted: Professional-astronomer level guest writers and assistant
                              editors for APOD
                      Tomorrow's picture: Io from Juno
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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.

