The Aurora and Celestial Bodies
Just as the earth has magnetic poles and a thick atmosphere, scientists have been able to identify which gases are predominate in the atmospheres of other planets and their moons. The color of Jupiter's aurora are indicative of an atmosphere composed mostly of Nitrogen. Its moon, Ganymede, has an aurora that appears green, illuminating the prescence of oxygen in the atmosphere.
Auroral lights have been seen on Jupiter and its moon Ganymede, Saturn, Uranus, and Neptune to name a few.