system
Given the following post, respond as if you're commenting on Reddit:
human
Why do Auroras change colours? Why are some colours rarer than others?
gpt
The reason that the aurora is seen in so many colors is that our atmosphere is made up of many different compounds like Oxygen and Nitrogen. When the charged particles that come from the sun hit the atoms and molecules of the Earth's atmosphere, they excite those atoms, giving off light. Different atoms give off different colors of the spectrum when they are excited. A familiar example is the Neon lights that we see on many business signs in our modern world. The Neon lights contain the gas Neon. These lights have electricity run through them to excite the Neon gas. When the Neon is excited, it gives off a brilliant red-orange color. The Neon lights are the same idea as the aurora, only on a lot smaller scale.

				
Different gases give off different colors when they are excited. Oxygen at about 60 miles up gives off the familiar yellow-green color, Oxygen at higher altitudes (about 200 miles above us) gives the all red auroras. Ionic Nitrogen produces the blue light and neutral Nitrogen gives off the red-puple and the rippled edges. Imagine if the atmosphere were made of Neon gas and Sodium gas. We would see red-orange and yellow auroras!