Modeling an enhancement of the lunar sodium tail during the Leonid meteor shower of 1998

A region of non-terrestrial sodium emission seen in the sky on the nights o f November 18-20, 1998, has been interpreted as the Moon's distant sodium t ail, possibly enhanced by micrometeor impact vaporization of the lunar rego lith by the Leonid meteor shower. We show, that the location and morphology of the spot can be explained by standard steady-state models of the Moon's sodium atmosphere. Moreover, using a new time-dependent simulation of the lunar atmosphere, we find that the Na escape rate from the Moon increased t o 2 or 3 times its normal level during the most intense period of the 1998 Leonid meteor shower on November 16th and 17th.