Pictures of the Aurora
Images of the Northern Lights are a sight to behold, but what causes the aurora? Discover the science and beautiful images of Earth's spectacular light show.
The aurora borealis, or the 'Northern Lights', is one of the most fabulous natural phenomena that can be seen on Earth: green, purple and pink wisps filling the sky creating an ethereal glow that really has to be seen to be fully appreciated.
The aurora is produced by a stream of charged particles emanating from the Sun - known as the solar wind - hitting Earth's atmosphere, where it strikes gas atoms and molecules - mostly oxygen and nitrogen - ionising them and producing a spectacular natural light show.
The aurora borealis is mostly seen in far northern climes, but it is possible to see the aurora from the UK given the right conditions: particularly in the north of Scotland.
For alerts as to when an auroral display could be imminent, follow Aurora Watch.
What causes different shapes and colours in the aurora?
The intensity of the solar wind and the stability of Earth's magnetic field both play a part in the strength and motion of the aurora borealis, or Northern Lights.
Auroral displays can vary significantly in shape and colour. Most commonly, the aurora appears green, a colour given off by oxygen at altitudes 100-150km above Earth.
Oxygen does have another excited state in which it can release a red hue, but this occurs much higher up at altitudes of about 200-250km.
Blue, violet and pink colours are released by nitrogen molecules. Nitrogen also emits turquoise-green and hydrogen gives out a pink-hued crimson.
Below is a selection of pictures of the aurora borealis captured by astrophotographers and readers of BBC Sky at Night Magazine.