Possible detection of meteor stream effects on the lunar sodium atmosphere

We report two sets of observations of sodium emission from the lunar atmosphere. The spectra were taken on two nights having very similar lunar phases, at various distances from the limb. Using Chamberlains model of the exosphere, we obtained values of the temperature, scale height and number density at the surface. These values differ significantly between the two nights. The spectra of the first night were taken when the Earth–Moon system was entering the Leonid meteor stream and show a marked increase in intensity, temperature and scale height relative to those of the second night, and relative to data for similar lunar phases published in the literature. We believe that this increase is related to an enhanced flux of micrometeoroids associated with the Leonid and possible with the Taurid meteor streams. The micrometeoroid component is generally considered the least important contribution to the sodium flux, and its distribution is assumed to be isotropic. We have previously suggested that an anisotropic and enhanced micrometeor component could be associated with meteor streams. The results reported below support this suggestion.