Aurora Borealis Of October 24, 2011

At 12:48 PM on October 24th, a coronal mass ejection (from a solar flare that left the sun on the evening of October 21st) hit the Earth.  This impact strongly compressed the Earth's magnetic field and created an intense geomagnetic storm.  The northern lights or aurora borealis were seen in Alabama, Arkansas, California, Colorado, Indiana, Iowa, Illinois, Indiana, Kansas, Kentucky, Maine, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Mexico, New York, North Carolina, Pennsylvania, Oklahoma, Oregon, Tennessee, Washington, and Wisconsin. 

Around 10 PM CDT on October 24th, the geomagnetic storm started to subside and the aurora rapidly weakened.  Besides the more common green colors, there were numerous reports of red colors during this event.
Aurora Borealis near Cross Plains, WI during the evening of October24, 2011 Aurora Borealis near Cross Plains, WI
during the evening of October 24, 2011


The term northern lights comes from the Latin word aurora which means dawn.  The northern lights usually exists at altitudes at 50 to 600 miles above the surface of the Earth in the layer of the atmosphere called the Ionosphere.  In this layer, both the oxygen and nitrogen molecules become excited by the increased radiation from solar flares.  During these times, the ionized particles are transported toward Earth where Earth's magnetic field deflects the charged particles toward the polar regions.  During this phase, the electron molecules begin to vibrate and upon returning to their normal state they emit light.  This is what we see as the northern lights.  The light displays from this activity are usually seen in curtains, arcs, streams, and bands.  Oxygen creates the green to brownish-red colors and nitrogen blue to red colors.

These events are monitored by NOAA's Space Weather Prediction Center:

More information on aurora borealis can be found at the following web site:





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