Nature's own fireworks

Northern lights is a result of our atmosphere shielding against solar particles which would otherwise make our planet uninhabitable The strong, green light originates at altitudes of 120 to 180 kilometres. Red northern lights occur at even higher altitudes, while blue and violet occur mostly below 120 kilometres. When the sun is "stormy", red colour occur at altitudes between 90 to 100 kilometres. Entirely red northern lights are sometimes seen, particularly at lower latitudes, and are often mistaken for a fire on the horizon. Courtesy :http://www.northern-lights.no/