How Auroras Actually Work

An aurora is a natural light display in Earth's upper atmosphere. Charged particles from the Sun cause it.

In the Arctic they are northern lights or aurora borealis. Geography is just branding.

Green dominates at lower altitudes because atomic oxygen emits at 557.7 nm. Atomic oxygen has a favourite colour.

Brown dwarfs also host auroras.

Higher up, excited atomic oxygen emits red light at 630 nm. It only shows up during intense solar activity.

Even lower down, molecular nitrogen radiates blue light at 428 nm. Blue shows during the highest solar activity.

Electrons trapped in the magnetosphere bounce along magnetic field lines. A 1960 rocket flight revealed electrons entering the atmosphere.

Electric fields between 4000 and 12000 km above Earth accelerate these electrons downward. Glowing air is one way to land.