Northern lights are one of the mysterious appearances on Earth. It is a celestial phenomenon whereby bands of coloured light flash across the skies especially in Arctic and Antarctic regions. In the Antarctic these lights are known as Aurora Australis or Southern Lights and in Arctic regions they are known as Aurora Borealis or Northern Lights. Such lights can be seen in less frequency outside these zones too. They are seen in various parts of Northern Scotland, but Finland is famous for the Northern Lights. The number of auroral displays in Finland can be as high as 200 any year.
There are many explanation for the phenomenon provided in the folklores. In the Finnish folklores it has been mentioned as “revontulet” or “fox fires”. The Finnish believed that these spellbinding celestial lights were caused by the arctic fox that sprayed fire or snow with their brush like tail. But the real cause of Aurora Borealis is sun.
Sun gives off high energy charged particles which are known as ions. These ions travel into space at a speed of 300-1200 kilometres per second. A cloud of sun particle known as the plasma is formed. The stream of plasma produced by the sun is better known as solar wind. When the solar wind comes in touch with the magnetic field of earth some particles are trapped by it and they go down following the lines of ionosphere. Ionosphere is the section of Earth’s atmosphere that extends from 60-600 kilometres above the earth’s surface. When the trapped materials collide with the gases in the ionosphere they start to glow producing the spectacle called Aurora Borealis and Aurora Australis. Some of the colours found in the Aurora include green, blue, red and violet.
Aurora Borealis is always in motion because there is constant change in interaction between the earth’s magnetic field and the solar wind. Solar winds generate up to 1000,000 megawatts of electricity in a auroral display. Such high discharge of electricity can also interfere with the radio, television broadcasts, power lines and satellite communications.
Recent studies have been dedicated to studying these Auroral displays and how the energy can be used for useful purposes.