| Abstract : | The lunar dust fountain model (DFM) from the literature[1,2,3,4] describes the lofting of dust on the moon's surface due to photoelectric effect from the sun’s rays. The like-charged surface and dust grains repel each other, such that under certain conditions the dust grains are lifted above the surface upto heights of around 100 cm above the surface near the terminator region.
We present an analysis of imaging and spectroscopy observations of the moon during various stages of a total lunar eclipse (27 July 2018). During the eclipse, filtered images of the moon (broad-band, IR, H-alpha, H-beta) were captured during various phases of the lunar eclipse using a 90mm Galilean Refractor and an ATIK 11000 Monochrome CCD. Simultaneously, moon spectra were captured using a 104mm MAK-Cassegrian telescope, equipped with a grism-mounted ALPY600 Spectrometer, polarizer, and a DMK 41AU02 CCD. The spectra were captured with three different polarizer orientations.
Analysis of standard spectral lines (Fe, Mg, Mn, Ti, Na) reveals greater absorption of the radiating dipole moment normal to the eclipse interface compared to the tangential direction. Invoking dipole radiation theory[5,6] and considering the polarized orientation of lunar dust particles in the electric field as described in the DFM, we explain the observed spectrum ratios. These findings would also contribute to understanding the dynamics of dust in planetary exospheres and their interactions with the solar wind.
References :
[1]Rennilson and Criswell, The Moon, Vol.10, pg.121 (1974).
[2]Zook and McCoy, Geophys. Res. Lett. Vol.18, pg.2117 (1991).
[3]Stubbs et al., Adv. Space Res., Vol.37, pg.59 (2006).
[4]Raghav et al., J. Geophys. Res. Space Physics, Vol.118, pg.6426 (2012).
[5]Heald and Marion, Classical Electromagnetic Radiation, Saunders, 1980, sec.9.2.
[6]Jackson, J. D. Classical Electrodynamics, John Wiley & Sons, 1962, sec.5.2
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