Saturn - Physical Characteristics

Physical Characteristics

Saturn is classified as a gas giant planet because the exterior is predominantly composed of gas and it lacks a definite surface, although it may have a solid core. The rotation of the planet causes it to take the shape of an oblate spheroid; that is, it is flattened at the poles and bulges at the equator. Its equatorial and polar radii differ by almost 10%—60,268 km versus 54,364 km, respectively. Jupiter, Uranus and Neptune, the other gas giants in the Solar System, are also oblate, but to a lesser extent. Saturn is the only planet of the Solar System that is less dense than water; about 30% less. Although Saturn's core is considerably denser than water, the average specific density of the planet is 0.69 g/cm3 due to the gaseous atmosphere. Jupiter has 318 times the Earth's mass while Saturn is 95 times the mass of the Earth, yet Jupiter is only about 20% larger than Saturn. Together, Jupiter and Saturn hold 92% of the total planetary mass in the Solar System.