NOTES: Saturn9.5 Dearth

Same atmosphere as Jupiter, but cloud obscures belts and zones.Tilt 26.7 degrees, Day = 10.5 hours, very oblate1/20th magnetic field of JupiterFeatures: belts and zones like Jupiter, small rocky core, occasional storms. Explored by Voyager I, II in 1979, 1988.Rings: 8 Rings--100,000 miles in diameter. Gaps are less visible rings, in particular Cassini Division. F Ring braided and shaped by shepherd moons. 20-100 m thick, kept from assembling by tidal force. Composed of ice and dust particles a micron to 10 m in size. They disappear for a few weeks every 15 years. Source may be unassembled nebula particles, broken up moons, or magnetic segregation. Spokes--black radial clouds caused by interaction with planetary magnetic field.Moons: 18. Titan--larger than Mercury, thick atmosphere (98 % N, 2% Methane, 1.6 pressure of earth). Liquid methane or Nitrogen oceans, similar to early conditions on earth except very cold. Hydrogen cyanide, ethane, and other organic compounds possible on surface. Bright, icy continents.Other moons are shiny, icy on the surface with some flow from interior, very cratered.

Planet: Number of Moons (2009)

Mercury 0Venus 0Earth 1Mars 2Jupiter 63Saturn 61Uranus 27Neptune 13Pluto 3

Saturn9.5 Diameter(earth)Same atmosphere as Jupiter, but cloud obscures belts and zones.

Saturn’s UV Aurora

Tilt 26.7 degrees, Day = 10.5 hours, very oblate1/20th magnetic field of Jupiter

Features: belts and zones like Jupiter, small rocky core, occasional storms. Explored by Voyager I, II in 1979, Cassini mission in 2004 and still going.

Rings: 8 Rings--100,000 miles in diameter. Gaps are less visible rings, in particular Cassini Division—big gap in rings (Cassini spacecraft flew through).

F Ring braided and shaped by shepherd moons.

Rings are 20-100 m thick, kept from assembling by tidal force. Composed of ice and dust particles a micron to 10 m in size. They disappear for a few weeks every 15 years. Source may be unassembled nebula particles, broken up moons, or magnetic segregation.

Rings disappear for a few weeks every 15 years.

Spokes--black radial cloud--caused by interaction with planetary magnetic field?

Moons: 37. Titan--larger than Mercury, thick atmosphere (98 % N, 2% Methane, 1.6 P(earth)). Liquid methane or Nitrogen oceans, similar to early conditions on earth except very cold. Hydrogen cyanide, ethane, and other organic compounds possible on surface. Bright, icy continents.

Huygens probe landing on Titan—found liquid methane oceans!

Other moons are shiny, icy on the surface with some flow from interior, very cratered.

Rotational vs magnetic axis of Uranus, Neptune

Uranus4.0 Dearth, -384 F--surface temp.Same atmosphere as Saturn, more methane, no visible belts.Extreme differential rotation--16 hrs at equator, 28 hrs at poles.

Discovered by WilliamHerschel, 1781

Features: Again dominated by mol. H and He, small rocky core, more methane giving surface blue-green appearance.Some underlying zonal flow and a deeper layer of water.Strong UV emission—electroglow. Twisted magnetotail.

In UV.

Rings: 11. faint ring system discovered by time lapse photos--shepherd moons hold black (.05 albedo) rings in place. Albedo = light reflected/light incident

Saturn’s shepherd moons—Uranus has them too.

Moons: At least 27. Strong radiation from planet turns methane in icymoon surfaces dark, so that icy moons are gray in appearance. Namedafter characters in Shakespeare (Oberon, Titania, Ariel, etc.). Moons arenot in ecliptic plane like most satellite systems--in same plane as Uranus'equator!!

Miranda--Probably broken up by collision (or tidal force of planet) and reformed

by gravity--radical mountains and valleys, fissures.Extreme Sports ‘Planet’.

Neptune3.9 D(earth), 60 K, gives off 3x energy received,extreme differential rotation.Discovered in a Jupiter conjunction in 1812by Galileo—he thought it was a star.

Features: Molecular H and He, methane makes blue, Hydrogen sulfide upper cloud layer with shape-changing cirrus white methane clouds. Great Dark Spot 3 earths large—disappeared ~1994.

Rings: 4 dark rings with shepherd moons.

Moons: At least 13 gray moons, most within equatorial plane. Exception is Triton: 2700 km diam. 23o orbital incl. to equator. Has tenuous N and methane atmos., pink and blue. S. polar cap looks like cantaloupe. Young surface, gaseous nitrogen geysers, glaciers.

Triton’s nitrogen and methane

ice geysers!

Nereid: eccentric captured asteroid--340 km diam.1.4-9.6 mill. km.

Largest period moon discovered. P = 360 days.

Hubble photo ofPluto across the surface of its largestMoon, Charon.Double tidal locking keeps the same side ofPluto facing it!Also the center of massfor the two is outside of Pluto’s surface! This is one reasonPluto was demoted To a Dwarf Planet.