Saturn

At the orbital semi-major axis of 9.539AU, Saturn’s sidereal revolution period is 29.458 years in a slightly eccentric (0.0556) orbit inclined 2.49° to the ecliptic. From the Earth, Saturn’s angular diameter at opposition is 20″.

Saturn has a thick cloud filled atmosphere that rotates differentially. The sidereal rotation period is 10h14m at the equator and 10h38m near the poles. The body rotation period is 10h39m. Saturn’s equator is inclined 26° 44′ to its orbital plane, so that alternate poles are tilted towards the Earth at intervals of ~ 15 years. The rotation causes a large oblateness (0.096).

Saturn is slightly smaller (9.0R) and less massive (95M) than Jupiter. It has the lowest bulk density of any planet, 680kgm-3.

The atmosphere of Saturn is like that of Jupiter, just at a lower temperature. Wind speeds are much higher on Saturn (500ms-1) than they are on Jupiter (100ms-1).

Saturn, like Jupiter, emits twice as much energy as it receives from the Sun. However, the mechanism behind this, must be different, and is probably due to Helium rain, falling through the liquid hydrogen interior.

Saturn must have a small rock and ice core, 14,000km in diameter, with a mass of 20M (25% of the total mass).

Saturn’s magnetic dipole has only 1/34 the strength of Jupiter’s, but is still strong enough to create a Jovian style magnetosphere with Earth like radiation belts. The dipole aligns with Saturn’s spin axis and the cloud-top field strength is 2.1 x 10-5T.

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~ by jamesdow2013 on May 1, 2013.

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