Auroras are usually green, and sometimes purple, but seldom do sky watchers see this much red. Red auroras occur some 300 to 500 km above Earth's surface and are not yet fully understood. Some researchers believe the red lights are linked to a large influx of electrons. When low-energy electrons recombine with oxygen ions in the upper atmosphere, red photons are emitted. At present, space weather forecasters cannot predict when this will occur.
During the storm, even more red auroras were observed over the United States in places like Kansas, Ohio, and Oklahoma. Browse the gallery for examples. Realtime Aurora Photo Gallery
THE INSTIGATING CME: The CME that hit Earth's magnetic field left the sun on Sept. 30th, propelled by an erupting magnetic filament. SOHO photographed the CME at the start of its journey, racing away from the sun at 2 million mph (900 km/s):
NOAA forecasters working through the government shutdown estimated an almost-even 45% chance of polar geomagnetic storms when the CME arrived. The CME justified those relatively high odds, sparking a G2-class geomagnetic storm around the poles.