Explanation Text : Aurora

How Does The Aurora Formed ?

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General Statement to Position the Reader	Aurora is a natural display of light in the sky that can be seen with the unaided eye only at night. An auroral display in the Northern Hemisphere is called the aurora borealis and in the Southern Hemisphere is called the aurora australis. Auroras are the most visible effect of the sun's activity on the earth's atmosphere.
Explanation	Auroral displays are associated with the solar wind, a continuous flow of electrically charged particles from the sun. When these particles reach the earth's magnetic field, some get trapped. Many of these particles travel toward the earth's magnetic poles. When the charged particles strike atoms and molecules in the atmosphere, energy is released. Some of this energy appears in the form of auroras.
Explanation	Auroras occur most frequently during the most intense phase of the 11-year sunspot cycle. During this phase, dark patches on the sun’s surface, called sunspots, increase in number. Violent eruptions on the sun’s surface, known as solar flares, are associated with sunspots. Electrons and protons released by solar flares add to the number of solar particles that interact with the earth’s atmosphere. This increased interaction produces extremely bright auroras. It also results in sharp variations in the earth’s magnetic field called magnetic storms. During these storms, auroras may shift from the polar regions toward the equator.
Explanation	The color of the aurora depends on which atom is struck, and the altitude of the meeting. 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