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by Chris Johnson
HISTORY OF AURORA BOREALIS
The Roman goddess of dawn Aurora, and her son Boreas, one of the winds in Greek mythology are the namesake of Aurora Borealis. Aurora (originally Eos in Greek mythology) was said to wake before everyone and ride her chariot across the sky bringing in the new day. The lights were named "Aurora Borealis" (meaning dawn-wind) by Pierre Gassed, in the year 1621 after he and Galileo witnessed one together. Early accounts of sightings appear in various texts, including the bible. The lights are described as being very bright, almost as if it was dawn at night. Borealis, or wind, was included in the name because the lights move as if they were dancing on the wind. Different native-American tribes and Australian aboriginal tribes have had different theories as to what was occurring when they witnessed the lights (in the southern hemisphere the lights are called Aurora Australis, Australis means 'of the south).
Aurorae are actually a scientific phenomenon, as opposed to a sign from any deity. Around the turn of the 19th-20th centuries Kristian Birkeland, a Norwegian scientist, theorized that The Northern Lights were caused by magnetism, after he read William Gilbert's study of the magnetism of the earth. Birkeland organized the first efforts to record and compile multiple sightings of Aurorae.
HOW AURORAE FORM
Aurora Borealis occur after atoms in the earth's atmosphere become charged with energy by solar flares. Solar flares, or solar wind is plasma (a mix of charged ions emitted from the sun and it's super-heated reactions which throw of atomic particles). The plasma is relatively concentrated and very far-reaching, with solar wind travelling past Pluto. When the wind passes by magnetized objects, like planets and moons, the ions in that direct area become attracted to the magnetic poles of the object. Magnetism and solar wind are not the only components of Aurorae though, atmospheric gases are needed to produce the light and colors. Nitrogen and Oxygen are just two of many gases that make up Earth's atmosphere. These two gases are also what usually make up the colors in the sky (other colors can be created when there are higher concentrations of other gases). Red and green are the most common colors on earth, although other colors have been seen as well, such as pink and purple.
Aurora Borealis can be seen most frequently around the magnetic north pole. The magnetic north is different from true north. Fairbanks Alaska is said to be the best place in America to witness Northern Lights, but the lights can be seen in Canada, Finland, Sweden, and Russia as well. Occasionally the Sun has more intense solar flares, which can cause Aurorae to appear closer to the Equator. Aurorae can happen anytime, but they are most likely to be seen during periods of intense solar storms. These storms can be erratic, but there seems to be a cycle that repeats around every eleven years.
MORE ON AURORAE
It is commonly accepted that Aurorae are a sight to behold. Many people take trips to the far North to witness them, and photographers have been tracking them ever since there were cameras. However, a less common experience is on of hearing Aurorae. There have been various claims throughout history that the Aurorae make noise. It has been hard to substantiate these claims up until now because the sounds associated with Aurora Borealis are so quiet and were often attributed to ambient noise. Recent scientific tests are now revealing the very strong probability that these lights can be heard as well.
Photo of Aurora Borealis courtesy of United States Air Force Senior Airman Joshua Strang [Public domain], via Wikimedia Commons.
Written by Chris Johnson
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