Using increasingly sophisticated observing strategies, astronomers have begun to observe brightness inhomogeneities on the surfaces of stars indicative of starspots, active regions, and chemically‐anomalous patches with size scales far smaller than the diffraction limits of the present generation of telescopes. While tantalizing, these first glimpses of stellar surface structures are very crude and not unique. Modest‐sized optical and ultraviolet inteferometers located on the lunar surface could resolve these surface structures on nearby, bright stars to provide ‘ground truth’ to the present crude images and to extend these studies to much smaller and physically interesting scales. The combination of broad and narrow‐band imaging (where feasible) will provide qualitatively new information on the physical processes that occur in stellar atmospheres by observing phenomena on stars with properties (mass, radius, convective zone depth, rotation rate) far different from the Sun. An intermediate scale optical/ultraviolet interferometer on the lunar surface with 10−3to 10−4arcsecond angular resolution would provide unique and spectacular results concerning stellar surface structures. This intermediate scale interferometer could be a very useful device for learning how to build larger interferometers that could address more difficult questions.