LUNAR REFLECTIVITY FROM EXTREME-ULTRAVIOLET EXPLORER IMAGING AND SPECTROSCOPY OF THE FULL MOON

We present new imaging and spectroscopic observations obtained with th e Extreme Ultraviolet Explorer (EUVE). Our 200 A image shows high cont rast (33%) anti complete albedo reversal, i.e., contrast is reversed r elative to the Moon in visible light. The high contrast at 200 A sugge sts the potential of the EUV spectral region for surface compositional studies. The 600 A image is surprisingly bland (< 3% contrast). We de rive surface reflectivities (geometric albedos) of individual surface regions for the first time with values of 0.11-0.15% at 200 Angstrom, and 2.5% at. 600 Angstrom. Reflectivities derived from the medium- (MW ) and long-wavelength (LW) spectra (140-380 Angstrom and 280-760 Angst rom) show that lunar reflectivity decreases by a factor of approximate ly 60 over the 700 to 150 Angstrom range. Our data further suggest tha t the Moon's brightness vs phase may behave differently than at longer wavelengths, and that sur face fluorescence may contribute to the obs erved EUV brightness.