June 28, 2010
On first glance, you would be forgiven for mistaking this picture for a painting; the creation of an artists imagination or the technical genius of a Photoshop wizard. This, however, is a photograph of the Aurora Borealis, or Northern Lights, shining above Bear Lake in Alaska taken by Senior Airmen Joshua Strang of the U.S.Air Force.
One of the most beautiful spectacles in our skies, the Northern and Southern lights are seen at night in polar regions, and appear as a green or redish hue along the horizon or as arcs of colour curling across the sky. The Southern Lights (Aurora Australis) are less photographed and reported due to there being fewer vantage points in the optimum 23 degree circle surrounding each magnetic pole where the lights are brighter and more frequent.
Aurorae are caused by a bombardment of protons and electrons streaming from space. These electrically charged particles come from the solar wind that pours from the sun in every direction. The earth’s magnetic field deflects most of these particles, however, near the magnetic poles (where particles are accelerated towards earth), some particles find their way into the atmosphere and collide with oxygen, nitrogen and other atmospheric gasses, which gain energy and in turn release it as a photon of light.
The green and brownish red light comes from oxygen light emissions and the blue or deep red come from nitrogen. Together creating great curtains of colour across the sky in hotspots along the northern hemisphere, from Norway to Alaska and Sweden to Greenland.
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