The aurora is caused by the interaction of highenergy particles (usually electrons) with neutral atoms in the Earth’s upper atmosphere. These high energy particles can “excite” (by collisions) valence electrons that are bound to the neutral atom. The excited electrons can then return to their initial, lower energy state, and in the process release photons (light particles). This process is similar to the discharge in a neon lamp.
|Credit: Andy Keen of Inari, Finland|