Northern Norway has been treated to a spectacular display of the Northern Lights.
The lights, also known as the Aurora Borealis, occurs when charged particles from the sun interact with air particles high up in the atmosphere.
The colours depend on which particle is hit. The most common colour is green, which is produced by oxygen about 100km above the Earth.
Nitrogen emits a blue light and oxygen very high in the atmosphere, about 300km above us, produces a red colour.
These lights can also be seen in the southern hemisphere, where they are known as the Southern Lights or the Aurora Australis.
Unless there is a particularly strong display of the Aurora, the lights are largely confined to the poles.
This is because the Sun’s particles are largely deflected by the Earth’s magnetic field, but the field is weaker at the poles, which allows some particles to enter the atmosphere.