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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