Aurora polar

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Aurora polar
Aurora borealis in Alaska.
The aurora is a glow that appears in the night sky usually in polar areas.
For this reason some scientists call "aurora polar " or " aurora polaris ".
In the northern hemisphere known as "northern lights" and in the southern hemisphere as "Aurora Australis", named Aurora the Roman goddess of dawn, Boreas the Greek word that means north, because inEurope commonly appears on the horizon of a reddish hue as if the sun emerged from an address unusual.
The aurora borealis, commonly occurs from September to October and from March to April.
Its equivalent in latitude, the aurora australis has similar properties.

Origin
An aurora borealis or polar occurs when a solar mass ejection collides with north and south poles of the Earth's magnetosphere,producing a diffuse light but predominantly projected in the terrestrial ionosphere.

Occur
When particles charged (Protons and electrons) from the Sun, are guided by the magnetic field Earth 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 air, part of the energy of the collisionexcites these atoms to the energy levels when they drop out such that the energy returned in the form of visible light.

The Sun, located 150 million km from Earth, continuously broadcasts charged particles: protons, positively charged and electrons negatively charged.
That is the stream of particles called the solar wind. The sun's surface or photosphere, is about 6000 º C, however, when oneascends the Sun's atmosphere to upper temperature increases rather than decrease, as intuition would suggest. The temperature of the solar corona the outermost zone that can be seen with the naked eye only during eclipses total sun reaches temperatures of up to 3 million degrees. The cause of this warming is the Sun's magnetic field, forming structures dramatic as seen in X-ray images As the pressurein the Sun's surface than in the empty space, the charged particles in the atmosphere of the Sun tend to escape and are accelerated and channeled
by the Sun's magnetic field, reaching the Earth's orbit and beyond.
There are very energetic phenomena such as flares or ejections
coronal mass which increase the intensity of the solar wind
The solar wind particles travel at speeds from 300 to 1000km/s,
so that roam the Earth-Sun distance in about two days. In
vicinity of Earth, the solar wind is deflected by the magnetic field Earth or magnetosphere. The particles flow in the magnetosphere of the same way it does a river around a stone or a pillar of a bridge. The solar wind also pushes the magnetosphere and distorts so that instead a uniform beam of magnetic field lines as those thatshow a magnet placed imaginary north-south into the interior of the Earth, which
has an elongated structure is shaped comet with a long tail in the
away from the Sun The charged particles have the property of being trapped and travel along magnetic field lines, so follow the path that will mark them. The particles trapped in magnetosphere collide with atoms and molecules of the Earth'satmosphere, typically oxygen (O), nitrogen (N) atomic and molecular nitrogen (N2) That are at their lowest energy, called the fundamental level. The energy input provided by the particles disturbs these atoms and molecules, leading to excited states of energy. After a very long small, the order of millionths of a second or even less, atoms and molecules return to ground level, and return the energy aslight.
That light is what we see from the ground and called auroras. The auroras remain above 95 km because at that altitude the atmosphere is so dense and collisions with charged particles occur so often that the atoms and molecules are practically at rest. On the other hand, the aurora can not be higher in the 500-1000 km because at that altitude the atmosphere is too
densely-bit dim so that few...
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