Thursday, October 13, 2011

Aurora Borealis

The aurora borealis is a phenomenon in the form of brightness or luminescence that appears in the night sky, usually in polar areas, although it may appear in other parts of the world for short periods of time. In the northern hemisphere is known as aurora borealis, and in the southern hemisphere as aurora austral.
The aurora of the northern hemisphere was named aurora borealis by the French scientist Pierre Gassendi in 1621, who was the first to make systematic auroral observations. The dawn of the South was named southern aurora by Captain James Cook in 1773, when he observed for the first time in the Indian Ocean. Already the Greek philosophers considered to the North as a natural phenomenon aurora, and her associated with the reflection of light in polar ice.

Aurora Borealis in Alaska
It occurs because the Sun follows charged particles whose set is called the solar wind, and travel through space and arriving at Earth, interact with the edges of the Earth's magnetic field. Some of the particles trapped by him, and follow the course of the lines of magnetic force in direction to the ionosphere.
The ionosphere is one of the layers that form the Earth's atmosphere and is characterized by high temperatures that reach it because the gases are ionized.
When these particles collide with the gas in the ionosphere, they begin to shine, producing the show we know as aurora boreal and austral. The variety of colors, red, green, blue and violet that appear in the sky due to different gases that compose the ionosphere. The Aurora Borealis is constantly changing due to the variation of the interaction between the bursts of solar wind and the Earth's magnetic field.
Chances of seeing the aurora borealis are greater between spring and the autumn equinox (September 21 to March 21). It is most frequent in late autumn and winter, and the best months to see are October, February and March. Their greater frequency is recorded between 6 pm and 1 am.
The skies Arctic and the North of Canada, Alaska, Norway and Spizbergen are the best scenario to see the aurora borealis.  The more dry weather with clear skies ensures better opportunities to see her, as they prove the statistics.

Aurora Borealis in Finland
Explanations about the origins of these fascinating lights of North abound in folklore.
In the Finnish language are called "revontulet", which means "Fox fires". The name is derived from an ancient legend about the Fox the Arctic claiming that the tails of foxes that ran by the Sami mounts, pounded against the piles of snow and sparks that came from such shocks were reflected in the sky.

The Eskimos, the Lapps, the inhabitants of Greenland, and even the tribes of the North-East of the India were familiar with this mysterious light in the sky. Their legends took many forms and were associated with their ideas of life on another world. According to an Eskimo legend, the aurora borealis was a footpath close, sinusoso and dangerous driving to the celestial regions and its light was due to the arrival of the new spirits.

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