Amazing Northern Lights Dancing

The Northern Lights, as the name suggests, are especially related to the polar regions, mostly in wintertime. They occur most frequently in a belt of radius 2500 km centered on the magnetic north pole. This so-called auroral zone extends over northern Scandinavia, Island, the southern tip of Greenland and continuing over northern Canada, Alaska and along the northern coast of Siberia.

The Northern Lights stem from when large numbers of electrically charged particles (electrons) at high speed stream in towards the Earth along its magnetic field and collide with the highest air particles. The air then lights up rather like what happens in a fluorescent light tube. The resulting colours reflect which gases we find up there, the most usual yellow-green colour coming from oxygen. Red colouring is also due to oxygen with a contribution from nitrogen. The violet we often see at the lower edge of the aurora is due to nitrogen, as is most blue colouring. The charged particles originate from the sun, and it is the “weather” conditions on the sun that decide whether or not we will see the aurora. Particles can stream out from the sun and some are captured by the Earth’s magnetic field and find their way into the polar regions. On the way, they travel out into the night side of the Earth and gain extra energy - we still lack understanding of exactly what happens out there!