Aurora Borealis Explained.

• Author: MIDDLETON, SAUNDRA
• Position: Brief Article

Sunspot activity causes the northern lights, or aurora borealis, yet it is not unique to the north. When the solar wind(a stream of particles and gas from the sun) comes in contact with the earth's magnetic field, spectacular light shows result near both magnetic poles. At the southern pole, aurora australis mirrors the northern display.

Solar flares occasionally explode from the sun's surface causing the best auroras. Other auroras result from energy release from the sun's dark holes during its normal today rotation, pausing a solar wind.

After a three-day space journey, the solar wind particles hit earth's magnetic field, painting shimmering bands, pulsing ribbons or curtains of color across the sky. Sometimes they drape overhead like an umbrella while at other times they merely light up the horizon with a green glow.

The colors of the aurora result from the solar flare or wind's charged particles coming in contact with various gases at different levels in the earth's atmosphere. Light yellow-green is most common and results from oxygen contact at about 60 miles above the earth. Blue or violet colors appear when the aurora contacts nitrogen in the atmosphere. The brilliant and rare all-red aurora glows from high-level oxygen 200 miles above the earth.

The elusive black aurora continues to baffle scientists. Professor Charles Deer at the University of Alaska Fairbanks Geophysical Institute calls it a reverse aurora. Deer describes it as an area of the sky where...