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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.

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

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

Date December 23, 2024
Credit Image Credit & Copyright: Jingyi Zhang
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.