Using the near-infrared spectral reflectance data of the Chandrayaan-1 Moon Mineralogy Mapper (M-3) instrument, we report an unusually bright structure of 30 x 60 km(2) on the lunar equatorial farside near crater Dufay. At this location, the 3-mu m absorption band feature, which is commonly ascribed to hydroxyl (OH) and /or water (H2O), at local midday is significantly (similar to 30%) stronger than on the surrounding surface and, surprisingly, stronger than in the illuminated polar highlands. We did not find a similar area of excessively strong 3-mu m absorption anywhere else on the Moon. A possible explanation for this structure is the recent infall of meteoritic or cometary material of high OH /H2O content forming a thin layer detectable by its pronounced 3-mu m band, where a small amount of the OH /H2O is adsorbed by the surface material into binding states of relatively high activation energy. Detailed analysis of this structure with next-generation spacecraft instrumentation will provide further insight into the processes that lead to the accumulation of OH /H2O in the lunar regolith surface.

Beyond Earth-like planets, moons can be habitable, too. No exomoons have been securely detected, but they could be extremely abundant. Young Jovian planets can be as hot as late M stars, with effective temperatures of up to 2000 K. Transits of their moons might be detectable in their infrared photometric light curves if the planets are sufficiently separated (greater than or similar to 10 AU) from the stars to be directly imaged. The moons will be heated by radiation from their young planets and potentially by tidal friction. Although stellar illumination will be weak beyond 5AU, these alternative energy sources could liquify surface water on exomoons for hundreds of Myr. A Mars-mass H2O-rich moon around beta Pic b would have a transit depth of 1.5 x 10(-3), in reach of near-future technology.