Atmospheric Gases     Gases make up the air we breathe. The main gases on Earth include: 78% nitrogen 21% oxygen 1% other gases (Argon, Neon, Helium, Krypton, Carbon dioxide etc.)   All the gases are atoms made up of protons, neutrons, and electrons which play a key role in the aurora. These particles have an attractive force that keeps them together. Photo from "Northern Lights" by Souza