Solar System information #11: Saturn

Saturn - the ringed giant

When seen through a telescope, Saturn is the most exciting planet in our solar system; its beautiful ring system can easily be seen. It is the second biggest planet, with a volume of about 760 Earths. The gas planets all have low densities, but Saturn's density is the lowest in the Solar System: less dense than water. It may have a solid icy or rocky core, but is composed mainly of hydrogen and helium. The outer atmosphere is mainly hydrogen and helium gas, with thick clouds of methane and ammonia. There is no solid surface - the planet is like a vast "sea" of liquid hydrogen and helium, perhaps as deep as 30,000 km.

Saturn's huge ring system may be matter that failed to come together to form a moon when the planet and its present moons were forming. Or the ring material may be from moons that broke up. Perhaps both of these explanations apply. The rings are made up of dust and ice and are more than 270,000 km in diameter, but only about 2 km thick.

Before the Voyager probes (1980-81), scientists thought that there were six major rings around Saturn. Voyager data shows that there are actually hundreds, even thousands, of narrow concentric ringlets making up the major rings.

Like Jupiter, Saturn is covered by thick cloud. Also, there are very strong winds, up to 1800 km/hr, near the equator; this is three times the speed of the winds on Jupiter. Huge cyclonic storms occur in Saturn's atmosphere, and there is evidence of possible lightning discharges. The energy powering all this atmospheric activity comes mainly from inside the planet, rather than from the Sun.

Saturn has more moons than any other planet in our solar system. The largest moon, Titan, is bigger than Mercury and Pluto. Titan has an atmosphere composed mainly of nitrogen and denser than that of the Earth. The 1983 discovery of carbon monoxide in the atmosphere of Titan suggests that the atmosphere may be similar to that of the early Earth; but it is probably too cold for life to ever begin there.