Oblique, vertically exaggerated view of a rift valley on Venus, generated by computer from data collected by the Magellan spacecraft's imaging radar system. Located in Ovda Regio, in the western part of Aphrodite Terra, the rift separates rougher highland terrain (on the left) from smooth lowland lava plain (on the right). Colour overlaid on the topography represents emissivity data gathered by Magellan, with red indicating the highest emissivity levels and violet the lowest. Emissivity is a measure of the natural radio and infrared emission of the surface materials, which provides clues about their composition.