Musings of a Political Scientist

Rings of Saturn

Planet Saturn by Bryan Brandenburg


Saturn is the sixth planet from the Sun. It is a gas giant (also known as a Jovian planet, after the planet Jupiter), the second-largest planet in the solar system after Jupiter. Saturn has a prominent system of rings, consisting mostly of ice particles with a smaller amount of rocky debris and dust. It was named after the Roman god Saturn (the Greek equivalent is Kronos, father of Zeus). Its symbol is a stylized representation of the god’s sickle.

Physical characteristics

Saturn is an oblate spheroid, i.e. it is flattened at the poles and bulging at the equator; its equatorial and polar diameters vary by almost 10% (120,536 km vs. 108,728 km). This is the result of its rapid rotation and fluid state. The other gas planets are also oblate, but to a lesser degree. Saturn is the only one of the Solar System’s planets that is less dense than water, with an average specific density of 0.69. This is a mean value; Saturn’s upper atmosphere is less dense and its core is considerably more dense than water.

Saturn’s temperature emissions. The prominent hot spot at the bottom of the image is at Saturn’s south pole.Saturn’s interior is similar to Jupiter’s, having a rocky core at the center, a liquid metallic hydrogen layer above that, and a molecular hydrogen layer above that. Traces of various ices are also present. Saturn has a very hot interior, reaching 12,000 Kelvin at the core, and it radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the Kelvin-Helmholtz mechanism (slow gravitational compression), but this alone may not be sufficient to explain Saturn’s heat production. An additional proposed mechanism by which Saturn may generate some of its heat is the “raining out” of droplets of helium deep in Saturn’s interior, the droplets of helium releasing heat by friction as they fall down through the lighter hydrogen.

Saturn’s atmosphere exhibits a banded pattern similar to Jupiter’s (in fact, the nomenclature is the same), but Saturn’s bands are much fainter and are also much wider near the equator. Saturn’s winds are among the Solar System’s fastest; Voyager data indicates peak easterly winds of 500 m/s (1116 mph)[3]. Saturn’s finer cloud patterns were not observed until the Voyager flybys. Since then, however, Earth-based telescopy has improved to the point where regular observations can be made.

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