Northern lights oval
The Northern Lights occur in a circular band around the geomagnetic north pole, otherwise known as the Northern Lights oval. It is a result of the atmosphere shielding the Earth against solar particles which would otherwise make the planet uninhabitable. On their way down toward the geomagnetic poles, the solar particles are stopped by Earth's atmosphere, which acts as an effective shield against these deadly particles. When the solar particles are stopped by the atmosphere, they collide with the atmospheric gases present, and the collision energy between the solar particle and the gas molecule is emitted as a photon -- a light particle. And when you have many such collisions, you have an aurora -- lights that may seem to move across the sky.
In this image, the Aurora Borealis glows in the sky in the Greenland town of Kangerlussuaq.
