An Etymological Dictionary of Astronomy and Astrophysics

The sixth → planet from the Sun and the second largest with an equatorial diameter of 120,536 km orbiting at an average distance of 1,429,400,000 km (9.54 → astronomical units) from Sun. With an → eccentricity of 0.05555,
its distance from the Sun ranges from 1.35 billion km (9.024 AU) at its → perihelion to 1.509 billion km (10.086 AU) at its → aphelion.

Its average orbital speed being 9.69 km/s, it takes Saturn 29.457 Earth years (or 10,759 Earth days) to complete a single revolution around the Sun. However, Saturn also takes just over 10 and a half hours (10 hours 33 minutes) to rotate once on its axis. This means that a single year on Saturn lasts about 24,491 Saturnian solar days.

Saturn has a mass of 5.6836 × 10²⁶ kg (95.159 → Earth masses) and a mean density of 0.687 g cm^-3.

Like Jupiter, Saturn is about 75% → hydrogen and 25% → helium with traces of → water, → methane, and → ammonia, similar to the composition of the primordial Solar Nebula from which the solar system was formed.

The temperature on Saturn is ~ -185 °C.

Like Jupiter, Saturn has a solid core of iron-nickel and rock (silicon and oxygen compounds). The core has an estimated mass of 9-22 Earth Masses and a diameter of about 25,000 km (about 2 Earth diameter). The core is enveloped by a liquid → metallic hydrogen layer and a → molecular hydrogen layer. Saturn’s interior is hot (12,000 K at the core). The planet radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the → Kelvin-Helmholtz mechanism as in Jupiter. Saturn has 62 known satellites. → Saturn’s ring. On 1 July 2004 NASA/ESA’s → Cassini-Huygens became the first to orbit Saturn, beginning a 13 year mission that revealed many secrets and surprises about Saturn and its system of rings and moons.

Etymology (EN): O.E. Sætern “Italic god,” also “most remote planet” (then known), from L. Saturnus, Italic god of agriculture, possibly from Etruscan.

Etymology (PE): Keyvân Mid.Pers. Kêwân, borrowed from Aramean kâwân, from Assyrian kaiamânu.