Astronomy

Aurora Borealis the Northern Lights



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The Northern Lights were named for an ancient Roman goddess and Greek god. In Latin, Aurora means dawn and Boreas comes from the Greek word for the north wind. The term dates back to 1619 when Galileo Galilei thought the display was a reflection of the morning sun. Credit is also given for its use in 1621 to the French astronomer Pierre Gassendi. Northern Lights have a counterpart in the Southern Hemisphere named aurora australis. The Geophysical Institute actually provides aurora forecasts at www.gedds.alaska.edu/AuroraForecast.

Northern Lights are most often seen in the darkest sky during the longest winter nights. Their splendor is truly mesmerizing to watch and surely one of the natural wonders of the world. Undulating ribbons or curtains of light - red, green, white, blue and sometimes purple - literally dance across the darkness around 100 km (or about 60 miles) above the earth.

Mythology

It's no wonder that the mystery of the aurora inspired myths and superstitions. In ancient times, people were afraid of the lights so everyone took shelter inside or, in the case of Lapps, covered their heads. Norse mythology claims the rays were shields of warriors riding to Valhalla. In Sweden, the lights are considered good luck for fishermen and in China and Japan, they symbolize fertility. Inuit people in the Canadian North believed the aurora held secrets to healing. Another Inuit legend is that the lights are the spirits playing ball.

History

The first known record comes from China in 2600 B. C., when the Emperor's mother reported that she saw strong lightning that illuminated the whole area. A drawing from 1570 pictures candles above the clouds. In the 1880s, scientists mapped where and how often auroras occurred. In the same century, a Norwegian physicist proved in an experiment that the light came from currents flowing through atmospheric gases. In 1954, a rocket launch detected auroral electrons. Today, you can see photographs taken by space shuttle crews as well as satellite images of the Northern Lights.

Science

The largest electric power plant generates a few thousand megawatts. Now imagine a million megawatts, more than all the lights of American cities. That's how much power results when geomagnetic storms cause disturbances and a solar wind carrying energetic particles from the sun blows across our magnetic fields. Basically, electrons overload the Van Allen radiation belt and become trapped in the magnetosphere. They move toward the polar ends of the earth and form auroras.

For more in-depth knowledge about the chemistry of Northern Lights, go to http://ds9.ssl.berkeley.edu/themis/mission_mystery.html.

If you've never seen the Northern Lights, just Google for images. If you get a chance to see them in person, don't miss this unforgettable experience.

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