... Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. ... Satellite and ground-based telescopic observations revealed the presence of a surrounding outer disk of material and an inner "clear" zone about the size of our solar system - strong evidence for the formation of planets. ... Uranian Moons, Rings, And Clouds . ... An inner moon, an edge-on, planet-girdling ring, and high altitude cloud bands are visible in this mosaic of infrared images of gas giant Jupiter...