THE VIEW FROM HERE
Although Saturn orbits nearly 10 times farther from the Sun than Earth does, it is relatively bright, shining at about 1st magnitude. That makes it easy to locate. Moreover, until it enters the star-rich region of Taurus, around the year 2000, Saturn will be among the dim constellations of Pisces, Cetus, and Aries, where few bright stars compete with it.
Being a gas-giant planet, Saturn has a structure much like Jupiter's—mostly gas and liquid with a small, dense core. The visible surface is the top ot an atmosphere containing hydrogen, helium, and other compounds such as methane, and the features we see are constantly shifting structures in the planet's cloud tops. Since it orbits farther from the Sun than Jupiter does, Saturn's environment is colder. This means it has less "weather" and displays fewer features.
To viewers with 3 inch (75 mm) scopes or smaller, Saturn's disk will appear featureless and creamy white. But in larger scopes, especially during good seeing, a pair of dusky bands paralleling the planet's equator becomes visible at about 20 degrees north and south latitude. These are called the north and south Equatorial Belts.
Viewing in twilight helps reveal these and other features. In full darkness, use a yellow filter to improve visibility. It helps to remember that belts are dark while zones are light.
The features contained between the two Equatorial Belts form what astronomers call System I, and they rotate once every 10 hours 14 minutes. System II includes everything else and has a rotation period of 10 hours 38 minutes.
At rare intervals, a white cloud breaks out in Saturn's Equatorial Zone. This occurred in 1990, when a small, bright patch appeared. Scientists think it was produced by a gigantic bubble of ammonia gas that rose from the depths and, upon reaching the chilly cloud tops, froze into white crystals and spread around the planet. Such eruptions seem to occur about every 30 years, but the cause remains unknown.
Another event occurs when Saturn lies 90 degrees away from the Sun in the sky— about 90 days before and after opposition. At this time, we can peer a little past one limb of Saturn and detect its shadow falling on the rings. The effect, though small, provides a visual hint of the planet's three-dimensional reality.