THE LUNAR OPPOSITION SURGE - OBSERVATIONS BY CLEMENTINE

The Clementine mission to the Moon in 1994 provided the first multispe ctral observations of the lunar opposition surge below a few degrees. The brightness of the Moon increases more than 40% between solar phase angles of 4 degrees and 0 degrees. The opposition effect exhibits a s mall wavelength dependence: the surge is similar to 3-4% larger at 0.4 1 mu m than at 1.00 mu m. This result suggests that the principal caus e of the lunar opposition surge is shadow hiding, while coherent backs catter, if present, makes only a minor contribution. The amplitude of the effect depends significantly on terrain: the surge is about 10% gr eater in the lunar highlands. This difference is attributed to textura l variations between the two terrains. The Clementine measurements pro vide a new basis for deriving spectral geometric albedos, phase integr als, and Bond albedos. A value of 0.11 +/- 0.01 was found for the luna r bolometric Band albedo. This value is at the low end of the historic al published values, but not as low as the recent result of 0.080 +/- 0.002. (C) 1996 Academic Press, Inc.