The Polar Lights or Aurora is an incredible and dramatic show of dancing lights that are seen around the magnetic poles of the northern and southern hemispheres. The unearthly show is caused by the electrically charged particles released from the sun that enter the earth's atmosphere and collide with gases like oxygen and nitrogen. The lights are displayed in the sky around the magnetic poles of the northern and southern hemispheres and are known as northern lights or Aurora Borealis in the north and Aurora Australis in the south. In 1619, Galileo coined the term ‘Aurora Borealis’, from the Roman goddess of the ‘Dawn’ and the Greek name for the north wind.
As the temperature above the surface of the sun is millions of degrees Celsius, collisions between gas molecules are frequent and explosive. Resulting from those violent explosions, the free electrons and protons are thrown from the sun's atmosphere by the rotation of the sun and escape through holes in the magnetic field. The escaped charged particles are then blown towards the earth by the solar wind and are largely deflected by the earth's magnetic field.
As the earth's magnetic field is weaker at the poles, some of the charged particles deflected from the sun enter the earth's atmosphere and collide with gas particles. These collisions cause the emission of heavenly lights that are displayed in the sky of the earth as the dancing lights of the north and the south.
Usually, the lights of the Aurora extend from 80 km (50 miles) to as high as 640 km (400 miles) above the surface of the earth. They may appear in different shapes and forms, from patches to rippling streamers or like rippling curtains or shooting rays that light up the sky with an eerie glow.
The colour and hue of the lights vary due to the types of colliding gases. Yellow and green are produced, when the particles collide with oxygen molecules located about 60 miles above the earth, while all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Blue displays are caused by the atomic nitrogen, while molecular nitrogen results in purple. Altitude also affects the colours. The green lights typically appear in areas up to 241 km (150 miles) high, while purple and violet above 60 miles. When the solar flares are particularly strong, the lights appear as a dancing curtain of ever-changing colour.
Areas that are not subject to 'light pollution' are the best places to watch for the polar lights. In North America, the best places to watch the Northern Lights or the
Aurora borealis are in the northwestern parts of Canada, particularly the Yukon, Nunavut, Northwest Territories and Alaska. The mysterious display of lights can also be seen over the southern tip of Greenland and Iceland, the northern coast of Norway and over the coastal waters north of Siberia. However, Aurora Australis or the Southern Lights are not often seen as they are concentrated in a ring around Antarctica and the southern Indian Ocean.