Monday, July 15, 2013

Polar Auroras: the psychedelic night

Which palette in the sky, the aurora black starry sky transform into a spectacle for the human eye almost by accident. Polar conditions of temperature and relative location with respect to the earth's mass to produce sol particles accumulate energy achieving such levels that eventually break down in a wide range of shapes and colors. Seeing is believing.
Aurora is a phenomenon as brightness or luminescence that appears in the night sky, now in polar areas, but may occur 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 and aurora australis, named
The Northern Lights are visible from September to March, though at times makes its appearance during the
course of other months, as long as the atmospheric temperature is low enough. The best months to see it are January and February, as it is during these months where temperatures are lower in the north. Its equivalent in south latitude aurora australis, has similar properties.
A polar aurora occurs when charged particles (protons and electrons) are guided by the Earth's magnetic field and affect the atmosphere near the poles. When these particles collide with atoms and molecules of oxygen and nitrogen, which are the most abundant components of the air, part of the collision energy to excite those atoms such energy levels (excited state) than when the energy is dissipated deenergized in visible light of various colors.
The colors we see in the aurora depend on the atomic or molecular species that excite solar wind particles and energy level reach those atoms or molecules: i) Oxygen is responsible for two primary colors of the aurora, green / yellow, ii) Nitrogen, at a collision can start some of their outermost electrons produces blue light, iii) while helium molecules are often responsible for the color red / purple lower edge of auroras and the curved outer parts.

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