Aug 21, 2013 9:50 AM by Stephen Bowers
Now that summer's end is approaching, the sun isn't up to brighten the night sky in the northernmost reaches of Earth. With the darker sky, the solar wind is able to add its own color and show to the sky.
The Aurora Borealis, commonly called "Northern Lights," will be increasing in frequency as winter approaches. The video below comes from northern Canada, Alaska, and Scandinavia near the Arctic Circle. Auroras that occur within 150 miles of the ground are usually green or blue in color, depending on the amount of oxygen and nitrogen in the air at the time. Auroras up above 150 miles are usually red or purple, also depending on the amount of oxygen and nitrogen in the air.
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The atmosphere near the equator is very deep and extends very high above Earth's surface. Near the poles, the atmosphere is not as deep. The thinner atmosphere near the North Pole and the Arctic Circle means auroras in those areas happen lower to the ground, taking on that green or blue color. Closer to the border of the U.S. and Canada, the atmosphere is thick enough that auroras occur higher in altitude, which means they are often red or purple or some variation of those colors.
The video comes from photographer Chad Blakely, who specializes in photography of auroras for the website Lights Over Lapland.
In the Southern Hemisphere, the same phenomenon is called Aurora Austrialis.