Geodessy is the measurement of a planet's shape and the location of surface features. During May 1999, the Wide Angle cameras were used aboard Mars Global Surveyor to map the whole planet at the resolution of 230 meters (750 feet,) per pixel. This 3d image shows an area from the Mare Tyrrhenum region, centered at 27.3 degrees S, 227.0 degrees W. The crater that dominates the center of the image is about 50 km (31 miles) across.   (26/53)