The blue-green color (lower right) is sunlight scattered off clouds high in Saturn’s atmosphere and the red color (upper left) is the glow of thermal radiation from Saturn’s warm interior, easily seen on Saturn’s night side (top left), within the shadow of the rings, and with somewhat less contrast on Saturn’s day side (bottom right). The darker areas within Saturn show the strongest thermal radiation. The bright red color indicates areas where Saturn’s atmosphere is relatively clear. The great variety of cloud shapes and sizes reveals a surprisingly active planet below the overlying sun-scattering haze.
This from the Cassini web site: an explanation of atmospheric studies of the ringed planet. The space probe images radiation at wavelengths beyond human sight, to gain clarity where human eyes would only see the mellow golden haze of the planet.
Notice the flattening of the planet. Despite being hundreds of times larger than our home planet, two of Saturn’s days are not quite equal to an earth day. That speed flattens the planet by several thousand miles. Earth is flattened too, but only by about thirty miles. Also notice the neat curve of the ring shadow. It’s what happens when a flat object casts a shadow on a curved one.
Spring is coming relatively soon (a few years) to Saturn, and scientists expect shifting patterns to reveal the extent of seasonal changes. Hopefully Cassini will be around past the planned end of its mission in summer 2008 to see it.