location, location, location

Let's think back to what started this whole thing: plasma from the sun interaction with gases in Earth's atmosphere. Well, here's something crazy about the air you breathe.... it glows. When the gases in Earth's atmosphere collide with the charged particles from the sun, they emit light. Interestingly, Oxygen glows green (and sometimes red depending on how high in the atmosphere the collision occurs) and Nitrogen glows blue or purple. Because Oxygen and Nitrogen make up the majority of the gases in Earth's atmosphere, these colors are the most prominent. However, green is most commonly seen.

photo cred: https://earthsky.org/earth/what-causes-the-aurora-borealis-or-northern-lights