A method is described for measuring spectral emissivity differences in the 8–13 µ region between two points on the lunar surface which may have different temperatures. Spectral emissivity differences of 0.5% on the moon can be detected in this wavelength region, excluding the strong 9.2–10 µ atmospheric ozone band where the accuracy is reduced to 2%. The application of this method to the bright planets is discussed.
Alexander F. H. Goetz and James A. Westphal, "A Method for Obtaining Differential 8–13 µ Spectra of the Moon and Other Extended Objects," Appl. Opt. 6, 1981-1983 (1967)