Auroras are bright displays of shimmering light that appear at night over the North and South Poles.
The Aurora Borealis is the Northern Lights, the aurora that appears above the North Pole.
The Aurora Australis is the Southern Lights, the aurora that appears above the South Pole.
Auroras are caused by streams of charged particles from the Sun known as the solar wind crashing into the gases of the Earth’s atmosphere.
Oxygen gas glows yellow-green when it is hit low in the atmosphere, and orange higher up.
Nitrogen gas glows bright red when hit normally, and bright blue when ionized.
Auroras form a halo of light over the poles all the time, but they are usually too faint to see. They flare up brightly when extra bursts of energy reach the Earth’s atmosphere from the Sun.
Auroras appear at the poles and nowhere else in the world because there are deep cracks here in the Earth’s magnetic field (see magnetism).
Auroras are more spectacular when the solar wind is blowing strongly.
New York and Edinburgh get an average of ten aurora displays every year.
The Northern Lights above the Arctic Circle are among nature’s most beautiful sights. Shimmering, dancing curtains of colour — bright green rays flashing with red, and streamers of white — blaze into the darkness of the polar night.