This shows a greyscale 3-mm image of the Moon, observed with the NRAO 12 Meter Telescope. The smoothly varying component of emission, corresponding to the temperature below the lunar surface, has been subtracted. This enhances some of the more subtle variations in emission, or temperature, of the lunar surface. Most of the features visible now correspond to shorter thermal time constants, such as might come from the top layer of dust on the surface. The boundary between large-scale light area and the dark area to the right delineates the lunar terminator.