The mythical aurora

The words magic or heavenly are often used to describe the colorful lights. There are actually two different kinds: the northern lights, or Aurora borealis, in the Northern Hemisphere and the southern lights, or Aurora australis, in the Southern Hemisphere.

The auroras mostly appear in a band known as the auroral zone around the geomagnetic poles. This one above Ireland was photographed from the ISS. The light you can see is the rising sun. The Aurora borealis can mostly be seen in Scandinavia, Iceland, parts of Greenland, Canada, Alaska and northern Siberia.

The southern lights are less famous than their northern cousin, but they're not any less spectacular. Around the South Pole, there are less inhabited areas - which means fewer viewing spots. When you're up high enough, that's not an issue anymore. Astronaut Tim Peake took this picture from aboard the ISS.

Auroras are created through the interaction of the Earth's magnetosphere and the sun's outer layer, the corona. When solar winds blow charged particles into the Earth's atmosphere, it blocks these particles. But a few of them make it through and collide with air molecules in the polar regions. The energy released during this collision results in spectacles like this one over Iceland.

There are four different kinds of auroras: coronas, curtains (pictured here), arcs and bands. Green light is produced by oxygen atoms hit at an altitude of 100 kilometers, red light by oxygen atoms hit at an altitude of 200 kilometers. Nitrogen atoms are responsible for purple and blue light.

Unfortunately there's no aurora guarantee, no matter where you're watching. You simply need a little luck and the right weather conditions: the clearer the sky, the better your chances! The same goes for darkness. If it's a pitch-black night, you are more likely to see an aurora.

The best place to see the Aurora borealis is the so-called aurora oval. It stretches across the geomagnetic pole in northern Greenland. Northern lights can be seen all year long in northern Scandinavia, Iceland, Greenland, northern North America and northern Siberia. But they most frequently occur at the equinox around September 23 and March 21.

Fair warning though: should you decide to go to Trondelag or Tromso in Norway, don't be disappointed if the northern lights don't look like the shots in our gallery. Aurora pictures are often more color-intensive than the real thing. Our advice: bring your camera and try different shutter speeds.