Ceraunius Tholus and Uranius Tholus are two volcanoes in the Tharsis region of Mars. Ceraunius Tholus is 130 km across and rises 5.5 km above its surroundings. The flanks of this volcano are etched with many valleys. Its neighbour, Uranius Tholus is a smaller volcano, with a base diameter of 62 km and a height of 4.5 km.
This image is derived from data acquired during three separate orbits of Mars Express, which took place between 25 November 2004 and 22 June 2006. During the second orbit, Mars Express’s camera captured icy clouds drifting past the summit of Ceraunius Tholus. In the finished mosaic image there is a sharp line because the clouds had long since dispersed by the time Mars Express crossed again and took the final strip of data needed for the image.