Danielle, Sarosh and Alli
Period Two
March 15, 2011

How the Aurora Borealis [Northern Lights] Forms

A picture of the Northern Lights
A picture of the Northern Lights

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The Northern Lights
The Northern Lights

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One of nature’s most spectacular phenomenon’s to date is the once unexplained aurora. This stunning show of lights has been seen by millions of people around the world for several years. Few people really know the cause of the Auroras. The reason of this report is to expose the truth behind how the auroras work. Known as the Auroras, there are in fact two Auroras. There are the Northern Lights known as the Aurora Borealis and the Southern Lights known as the Aurora Australis. Both are a mirror image of each other. The Northern Lights get more exposure rather than the Southern Lights. The Northern Lights occur in the northern hemisphere closest the North Pole. The best places and time to view the Auroras are at high northern latitudes during the winter in Alaska, Canada, and Scandinavia. The colors of the Aurora Borealis are usually lights of green and yellow and sometimes red.

To understand the Aurora Borealis, one must understand what causes them to form. The Northern Lights are not just magically formed. There is much more behind them. The Auroras form when solar winds enter into the Earth's magnetic field. The sun has a powerful magnetic field and is endlessly emitting solar wind particles. Solar wind particles are electrically neutral flow of hot plasma that the sun discharges in all directions. The charged particles, blast out from the sun at speeds between 1 million and 3 million kilometers per hour. As we know, the earth contains a magnetic field, and with this the solar winds combine with it to form earth magnetosphere. This magnetosphere forms a "bow shock". Some of the particles get brought up into the Earth's magnetic field and travel along down towards the magnetic poles. When this happens the particles electrify the gases in the Earth's atmosphere causing them to give off light. In the atmosphere, after the electrons become energized they snap back to there normal positions and emit a light. When oxygen gas becomes energized, it gives off blasts of soft greenish light giving us the aurora.

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The formation of the Auroras from the sun

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The Auroras do not just give off random colors. They are usually green, red, blue or purple for a reason. As the electrons enter the earth's upper atmosphere, they will come across atoms of oxygen and nitrogen at altitudes from 20 to 200 miles habove the earth's surface. The color of the aurora depends on which atom is struck, and the altitude of the meeting. The different colors of the Auroras and their altitudes are shown below:

Green - oxygen, up to 150 miles in altitude
Red - oxygen, above 150 miles in altitude
Blue - nitrogen, up to 60 miles in altitude
Purple/violet - nitrogen, above 60 miles in altitude.

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A chart of composition and density of the atmosphere and the altitude of the aurora that determines the possible light emission colors

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The aurora is actually present at both poles at every moment of the day and night. The best time to observe the Auroras are around midnight when the sky is at its darkest. Most people don’t know that the auroras produce an enormous amount of electricity. The electricity is formed when a good conductor experiences a changing magnetic force.


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