Question: How do northern lights happen

Jonathan Mound answered on 1 Apr 2026:

The northern (and southern) lights happen when atoms in the atmosphere get “excited”. The solar wind is a mass of charged particles that travel at high speeds (100’s of km/s) from the Sun to Earth. When they arrive at the Earth they can collide with atoms in the upper atmosphere. The atoms in our atmosphere now have extra energy which they get rid of by emitting light. Each atom has particular colours of light that they emit; for example, oxygen makes red or green, nitrogen makes blue or purple.

This is similar to how “neon” lights work. Tubes with different gases trapped inside glow at different colours when a current is passed through them.