Cause of terrestrial nightglow continuum

Abstract

Since the nightglow’s green continuum was discovered over 40 years ago the theory that it arises from the NO 2 air afterglow has been generally accepted so that its intensity is regarded as a useful measure of the abundance of nitric oxide in the lower thermosphere. This theory is shown to be untenable. Observational evidence points unambiguously to a novel source: metastable oxygen molecules colliding with ambient gas molecules and thereby forming complexes that dissociate by allowed radiative transitions.