NOTES: Saturn 9.5 D earth Same atmosphere as Jupiter, but cloud obscures belts and zones. Tilt 26.7 degrees, Day = 10.5 hours, very oblate 1/20th magnetic field of Jupiter Features: belts and zones like Jupiter, small rocky core, occasional storms. Explored by Voyager I, II in 1979, 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 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 0 Venus 0 Earth 1 Mars 2 Jupiter 63 Saturn 61 Uranus 27 Neptune 13 Pluto 3

Saturn 9.5 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 oblate 1/20th 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 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

Uranus 4.0 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 William Herschel, 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.

Miranda--Probably broken up by collision (or tidal force of planet) and reformed by gravity--radical mountains and valleys, fissures. Extreme Sports ‘Planet’.

Neptune 3.9 D(earth), 60 K, gives off 3x energy received, extreme differential rotation. Discovered in a Jupiter conjunction in 1812 by 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. 23 o 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 km diam mill. km. Largest period moon discovered. P = 360 days.

Hubble photo of Pluto across the surface of its largest Moon, Charon. Double tidal locking keeps the same side of Pluto facing it! Also the center of mass for the two is outside of Pluto’s surface! This is one reason Pluto was demoted To a Dwarf Planet.