Color Differences on the Lunar Surface

Citation

McCord, Thomas Bard (1968) Color Differences on the Lunar Surface. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0ST8-5H98. https://resolver.caltech.edu/CaltechTHESIS:02082012-092701057

Abstract

Both a detailed literature survey and a new observational study were performed to determine and extend the knowledge of spectral reflectivity differences (color differences) on the lunar surface in the extended visible wavelength region. A survey of the extensive and disorganized literature revealed few positively known facts and indicated the need for an accurate, multi-passband observational study of a number of lunar areas of differing morphology. A 21-filter (0.4µ- 0.8µ), double beam photoelectric photometer was designed and constructed to observe differentially 83 lunar areas, some many times, to an accuracy of 0.1% to 0.3%. Some results were the discovery of: (1) many color variations up to 10% with some to about 60%, (2) a dependence of relative color on phase angle but no temporally varying luminescence, (3) broadband absorption features on spectral reflectivity curves and possibly some less broad, low amplitude (0.2%- 0.5%) humps, (4) a dependence of spectral curve shape on lunar morphology and, (5) no universal dependence of color on brightness, although some mare areas show this tendency. These results indicate that color differences are caused mainly by compositional differences and that the shapes of the spectral reflectivity curves give some indications of the rock and mineral composition of the lunar surface.

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