Apod: Saturn at Night
It is the sunlight that reflects off Saturn's rings that causes the planet to glow at night. The Southern hemispere glows because of the reflected light from the rings. The light, however, does not penetrate the rings enough to brighten the northern hemisphere theirfore the northern hemisphere remains dark. Although the rings are bright, part of the rings are cut off by the planet's shadow, but if you look closely enough you can see the C-rings, the second most inner set of rings of Saturn.
This image is taken from the Cassini spacecraft which is now orbiting Saturn. The craft was 592,000 miles from saturn at an angle of 124 degrees.