Monitoring the moon's transient atmosphere with an all-sky imager

Abstract

Abstract An indispensable tool in terrestrial aeronomy, all-sky imaging has recently been shown to be useful in studies of the Moon's exosphere. Two days after the peak of the 1998 Leonid meteor shower, an extended region of neutral sodium emission was detected in the night sky using a bare-CCD imaging system. The feature was found to be a train of sodium gas originating from the Moon. Subsequent observations indicate the feature is normally visible (max. brightness ∼15–90 Rayleighs (R)) during nights near the time of new Moon. Monthly monitoring of the feature using an all-sky system can provide useful information about the time-variability of the lunar atmosphere. Several processes are believed to be responsible for the production of lunar Na and evidence is presented indicating that two of these processes were each responsible for the observed brightness enhancements of the sodium feature on two separate new Moon periods in January and March 2000.