Discovery of the distant lunar sodium tail and its enhancement following the Leonid meteor shower of 1998

Night-time measurements using a bare CCD all-sky imaging system have detect ed the presence of an extensive region of neutral sodium emission (589.1 nm ) in the direction of the anti-solar/lunar points. The emission was observe d to occur during the nights of 21-22 August and 18-20 November, 1998 UT, c entered on the new Moon period. The Moon is the most likely source of the n eutral sodium, making this the first detection of the lunar sodium tail out to a distance of hundreds of lunar radii. The greater brightness of the em ission feature on 19 November is attributed to the Leonid meteor shower whi ch peaked on 17 November, 1998, less than two days before new Moon.