Scientists and observers monitor IBIS--the Interferometric Bidirectional Imaging Spectrometer--as it records the transit of Mercury across the face of the Sun on Nov. 8, 2006, at the National Science Foundation's (NSF) Dunn Solar Telescope in Sunspot, N.M. In this experiment, Mercury was used as a knife edge moving across the face of the Sun, momentarily enhancing resolution, and the Sun was used as a light source to probe the extremely thin atmosphere of Mercury. IBIS, developed by INAF/Arcetri Astrophysical Observatory, combines high-spectral resolution with short exposure times and a large field of view, as well as the ability to work in polarized light. This allows it to address a variety of observational programs in solar physics. The Dunn's adaptive optics control station is at bottom center in this image, and the Sun's image is projected onto the guide camera just above it.