|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 October 24, 2011
These events are monitored by NOAA's Space Weather Prediction Center: http://www.swpc.noaa.gov/
More information on aurora borealis can be found at the following web site: http://odin.gi.alaska.edu/FAQ/