Modeling the Moon's extended sodium cloud as a tool for investigating sources of transient atmospheres

A review is presented of wide-angle, low-light-level imaging observations of the Moon's extended sodium atmosphere and Monte Carlo simulation studies used in their interpretation. The observational results at quarter and full Moon show dramatically different morphology patterns. The computer model results show that both morphologies are consistent with a single source function and subsequent dynamical evolution of the ejected sodium atoms. Different viewing geometries essentially account for the observational differences. We thus find no need to modify source rates significantly during full Moon periods when the terrestrial magnetosphere shields the lunar regolith from possible solar wind sputtering sources.