WHY are the auroras multicolored? During collisions, atmospheric atoms can lose electrons (ionize) or turn into an excited state for a short time.
Photons with different wavelengths are emitted, which is what the human eye or camera sees.
Oxygen is responsible for the green or brownish-red color, as well as the greenish-yellow polar lights. Other constituents of the atmosphere also make small contributions, such as
hydrogen and helium giving blue and purple colors.
