Solar System -


Visually, Saturn, with its glorious ring system, is the most spectcular planet in the Solar System.  It is the second largest planet after Jupiter, and the sixth planet out from the Sun which it orbits at an average distance of about 1,433 million km (896 million miles) approximately once every 29.46 Earth years.  A day on Saturn lasts only 10 hours 39 minutes and 22.4 seconds based on radio emissions.  Its equatorial diameter is a little over 120,000 km (about 75,000 miles) but the flattening at the poles caused by its rapid rotation means it is around 10% less in diameter across the poles.  Saturn's density is the lowest of all the planets, and it is less dense than water at 0.687 gm/cubic cm; less than one eighth the density of the Earth.  Of course, this is just the average density.  The density in the rocky core would be much higher, while in the outer layers, it ould be much lower. 

The atmosphere is much more hydrogen rich than Jupiter's, being about 96% hydrogen, 3% helium and 0.4% methane with traces of ammonia, ethane and other elements.  The middle region is mainly ices of ammonia, water and ammonium hydrosulfide.  There is probably a small core of rock and ice.  Saturn's density is less than that of water, and it has the lowest density of any of the planets.  Jupiter, while only about 20% larger, weighs well over three times as much as Saturn.  Its volume is equivalent to nearly 764 Earths, but its mass is only around 95 earths.  Its magnetic field is about 7 times stronger than Earth's, or half Jupiter's. 

The outer layers of the atmosphere are at a temperature of about 90K (-183C).  Further down, there is a layer of water ice at around 250K (-23C), while core temperatures reach 11,500K.  Winds can reach over 1,100 miles (1,760 km) per hour, which is faster than the winds on Jupiter.  Saturn has a very interesting hexagon shaped wave pattern around the north pole.that it rotates at the same rate as that established by radio emission from the interior.  More information on this feature on the Images of Saturn page. 


Credit: NASA/JPL/Space Science Institute