What generates the different colors observed in the auroras?

The different colors observed in auroras are primarily generated by the type of atmospheric gas that is being ionized. When charged particles from the solar wind collide with gases in Earth's atmosphere, such as oxygen and nitrogen, they excite those gas molecules. As these excited molecules return to their normal state, they release energy in the form of light, resulting in the various colors of the auroras.

For example, collisions with oxygen at lower altitudes (around 60 to 150 miles above the earth) typically produce a red or yellow color, while those at higher altitudes (above 150 miles) can create green hues. Nitrogen can produce different colors, too, like blue and purple, depending on the specific interactions occurring during these collisions. Thus, it is the variety of gases present in the atmosphere and how they react to energetic solar particles that ultimately determines the colors we see in auroras.