The Northern Light, or Aurora Borealis as someone calls it, is the natures own gigantic light-show. This special light phenomenon can bee seen on the northern and southern hemisphere (Northern Light and Southern Light respectively) if circumstances are right.
Extremely simplified, we can say that the Northern Light occurs when the particles from the sun are being thrown against the earth by the solar wind. When the particles collide with the earths atmosphere, the energy of the particles are turned into light, the Northern Light.
In order to be able to study the cause of the Northern Lights, we must concentrate on processes that occur on the sun;
The sun has a number of holes in its corona from which high energy particles stream out with enormous velocity. These particles are thrown out through our solar system, and the phenomena is called solar wind.
Some of this solar wind meets the earths magneto sphere, compressing it on the daylight side, while drawing it out in a tail on the nighttime side. From out in the magnetic the solar wind particles are accelerated down to the earth again along the open magnetic field lines. The field lines are open only in the polar regions. At lower latitudes the field is locked. Thats why we have the Northern Lights only in the polar regions.
When the solar wind particles collide with the air molecules, their energy is transferred into light. It is billions of such processes occurring simultaneously that produces the Northern Lights.
