This image, taken by NASA?s <I>Cassini</I> spacecraft on December 1, 2000, shows details of Jupiter?s Great Red Spot. In this color composite with enhanced contrast, the closest of Jupiter?s four large moons, Io, is visible on the left. The edges of the Red Spot are cloudier with ammonia haze than the spot?s center. The Red Spot?s region has changed in one notable way over the years: in images from NASA?s <I>Voyager</I> and <I>Galileo</I> spacecraft, the area surrounding the Red Spot is dark, indicating relatively cloud-free conditions; however, now some bright white ammonia clouds have filled in the clearings, which appears to indicate a general brightening of Jupiter?s cloud features during the past two decades. Io?s more than one hundred active volcanoes spew lava and giant plumes of gas and dust; its biggest plume, Pele, is visible here near the bottom left edge of Io?s disk.