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.
Read more about this topic: Saturn
Famous quotes containing the word physical:
“Even the simple act that we call going to visit a person of our acquaintance is in part an intellectual act. We fill the physical appearance of the person we see with all the notions we have about him, and in the totality of our impressions about him, these notions play the most important role.”
—Marcel Proust (18711922)