AURORAS

■ AURORAS

◇ Aurora is the name given to the luminous glow in the upper atmosphere of the Earth which is produced by charged particles (solar wind) descending from the planet's magnetosphere.

◇ Positive ions slowly drift westward, and negative ions drift eastward, giving rise to a ring current. This current reduces the magnetic field at the Earth's surface.

◇ Some of these particles penetrate the ionosphere and collide with the atoms there.

◇ This results in an excitation of the oxygen and nitrogen molecular electrons. The molecules get back to their original state by emitting photons of light which are the aurorae.

◇ The charged particles follow magnetic field lines which are oriented in and out of our planet and its atmosphere near the magnetic poles. Therefore, aurorae mostly are seen to occur at high latitudes.