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.

2014 March 24
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Orion and Aurora over Iceland
Image Credit & Copyright: Žorvaršur Įrnason

Explanation: If you see a sky like this -- photograph it. A month ago in Iceland, an adventurous photographer chanced across a sky full of aurora and did just that. In the foreground lies the stratovolcano Öręfajökull. In the background, among other sky delights, lies the constellation of Orion, visible to the aurora's left. Auroras are sparked by energetic particles from the Sun impacting the magnetic environment around the Earth. Resultant energetic particles such as electrons and protons rain down near the Earth's poles and impact the air. The impacted air molecules obtain excited electrons, and when electrons in oxygen molecules fall back to their ground state, they emit green light. Auroras are known to have many shapes and colors.

Click Hyperspace: Random APOD Generator
Tomorrow's picture: dusty hunter


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