When do they appear?
Our forefathers seemed baffled when they had tried to guess the causes of such enigmatic show in the night sky. They had predicted the causes which today one can only consider senseless. They had imagined that near the poles sun gets so close that its flames reach the earth or there might be fires blazing up around the ocean or they had even thought that glaciers might illuminate themselves by storing energy and many other stories were created to explain them. But the real scientific reason behind them is that they occur due to collision between the solar particles and earth’s atmosphere, releasing photons of energy from the excited atoms in the upper layers (Ionosphere) of atmosphere which gives supernatural and colourful appearance. The reason that it happens only at the poles is that the earth’s magnetic field attracts the solar particles towards its magnetic poles. Since the earth’s magnetic field is constantly changing, they appear constantly swaying to and fro like a fluorescent curtain in the breezy weather.