Composite image of Io, one of Jupiter's moons and the most volcanic body in the solar system, taken by the Galileo spacecraft in September and November of 1996. Color images have been merged with higher-resolution images to produce a detailed composite, revealing features as small as 2.5 kilometers. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top.