Theories of the origin of the night sky light are discussed. It is pointed out that evidence from the absolute intensity, the altitude, the space and time variations, the correlations with magnetic activity, and the particular lines and bands appearing in the spectrum, indicates that the emission is not solely connected with the potential energy associated with the region of dissociated oxygen or with the ionized layers but partly arises from incident charged particles (such as produce aurorae). The suggestion is made that it is the action of the Störmer current that allows these particles to approach sufficiently close to the Earth at low latitudes.