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Aurora borealis

Aurora borealis in Alaska.La aurora is a glow that appears in the night sky, usually in polar areas. For this reason some scientists call "polar aurora" (or "aurora polaris"). In the northern hemisphere is known as "aurora borealis" and southern hemisphere as "Aurora Australis", named Aurora the Roman goddess of dawn, and 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 is visible from October to March, though the best months are January and February see it as it is during these months where temperatures are lower. Its equivalent in latitude, aurora australis has similar properties.

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

They occur when charged particles (protons and electrons) from the Sun, 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 air, part of the energy of the collision excites these atoms to energy levels such that when deenergize return this energy as visible light .

The Sun, located 150 million km from Earth, is continually emitting charged particles: protons, positively charged and electrons negatively charged. That is the stream of particles called solar wind. The sun'ssurface or photosphere, is about 6000 º C, however, when you go in the sun's atmosphere into the upper layer temperature increases instead of decreasing, as intuition would suggest. The temperature of the solar corona, the outermost zone which can be seen with the naked eye only during total eclipses of the sun reaches temperatures of up to 3 million degrees. The cause of this warming is the Sun'smagnetic field, which is spectacular structures as seen in X-ray images As the pressure in 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 more there. There are very energetic phenomena such as flares or coronal mass ejections that increase theintensity of the solar wind.

It is called aurora borealis when observed this phenomenon in the northern hemisphere and aurora australis when observed in the southern hemisphere. There are no differences between them.

The Finnish expression of the aurora borealis, "Revontuli" comes from a fable or Saami Lapp. Repo means fox (short) and tuli fire. Therefore Zorro.Según Fire Revontuli is legend,the tails of foxes running through the forest Lapps, beat against the piles of snow and sparks coming out of such blows were reflected in the sky. Asians believe that after seeing the Aurora Borealis, live happy the rest of your life. Especially is believed to be a source of fertility.
The colors and shapes of the auroras

Northern Lights from the ISS business social Auroras have forms verydifferent structures and colors are shifting rapidly with time. During one night, the aurora may initially be a very long single arch which is spreading on the horizon, generally in an east-west. Around midnight, the arc may start to increase their brightness. Begin to form waves or curls along the arc and vertical structures that look like rays of light very elongated and thin. Suddenly the wholesky can be filled with bands, spirals, and light rays that tremble and move rapidly from horizon to horizon. The activity can last from a few minutes to hours. When dawn approaches the whole process seems to calm down and only a few small areas of the sky appear bright until morning comes. Although he described is a typical night of auroras, we may find many variations on the same topic.

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