Wednesday, November 23, 2011

Aurora Borealis

The aurorae are luminous phenomena that appear mainly in the polar regions, North and South; they are respectively the aurora borealis and the southern aurora.

the polar aurorae are caused by a radiation of charged particles from the Sun, forming what is called the solar wind. Electrons and protons coming from this radiation are "trapped" by Earth's magnetic field, and collide with the ionosphere. This is a layer made up the Earth's atmosphere, which is composed of gases ionized and subjected to very high temperatures. As from the Sun particles collide with different gases of the ionosphere, they give rise to brightness and lights, as well as a variety of colors that make the show one of the most impressive nature.

It sometimes seems that the auroral curtain almost touch the ground. However, this phenomenon only occurs between 100 and 1,000 miles of the Earth's surface. The clashes that take place at lower altitudes create shades of yellow and green, while a larger altitudesproducen red light emission and blue. Some polar auroras are huge--they may reach 3 to 5 miles thick and more than 160 kilometers of height- and literally extend thousands of miles.

In Greenland, Iceland North Norway or Alaska, the aurora borealis can be seen some two hundred forty nights a year. In the North of Siberia and the central region of Canada is about a hundred nights a year, while those who reside in southern Alaska only watch a few five nights a year.

In the Centre of Mexico you can see an auroral event every ten years. This is due to the Aurora rely on solar activity and its intensity is greater when the corpuscular radiation increases during solar flares. The intense solar flares can cause visible Aurora outside common areas; lights even in Equatorial areas with an average of once every ten years can observe.

The activity of the polar Aurora is maximum in autumn and spring. The regions most prone to express this phenomenon are which are placed in a circle of 22 °of latitude from each of the magnetic poles of the Earth.

In principle, the most intense polar auroras may provide for. Indeed, they occur in relation to the solar flares that can be detected through telescopes and observatories. It is known that the particles that have been thrown from the Sun after eruptions take 15 to 30 hours to reach the Earth's atmosphere.

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