Sporadic radiant emission from the upper atmosphere that usually occurs about the North and South magnetic poles of the Earth. Note 1: Auroras are most intense at times of intense magnetic storms caused by sunspot activity. The distribution of auroral intensity with altitude shows a pronounced maximum near 100 km above the Earth. Auroras may occasionally be observed within 40° or less of the equator. Note 2: Auroras interfere with radio communications. Note 3: In the Northern hemisphere, the aurora is called the Aurora Borealis (Northern Lights. ) In the Southern hemisphere, the aurora is called the Aurora Australis (Southern Lights. )