Aurora

Aurora, display of colored lights and shimmering forms seen at night, most frequently during the equinoxes, in regions of high latitude. The aurora borealis, or northern lights, can be seen in northern Scandinavia, Canada, and Alaska, and the aurora australis, or southern lights, are seen on the borders of Antarctica in the Southern Hemisphere. Fast-moving electrons from the sun are attracted to the earth's magnetic poles, where they collide with oxygen and nitrogen ions in the ionosphere, causing them to give off energy in the form of light. The aurora most frequently appears following a major solar flare; the occurrence and intensity of the aurora is also related to the 11-year sunspot cycle.