Lunar albedo at hydrogen Lyman α by the NOZOMI/UVS

Abstract

The geometric albedo of the Moon at the wavelength of hydrogen Lyman α (HLyα 121.6 nm) was derived from an imaging observation by the ultraviolet imaging spectrometer (UVS) during the lunar encounter of the NOZOMI spacecraft. The solar HLyα irradiance data measured by the UARS/SOLSTICE at the time of UVS observation were adopted. We obtained an average geometric albedo of 5.2 ± 0.9% for the sunlit region where the UVS observed. Our result agrees with the geometric albedos obtained from the observations by Apollo 17 and Astro-2/HUT, though the observation geometry and area are completely different from each other. There exists a significant difference of the albedos from place to place in the observed lunar surface ranging from 2.3 ± 1.1% to 6.0 ± 1.0%. It is noted that the observed contrast at the FUV wavelength is positive to that seen in the visible region.