The Jovian Planets,Part II

Saturn

SATURNThe God of Agriculture

Physical Data

Diameter: 119,871 km (9.41 Dearth)

Mass: 5.69x1029 g (95.1 Mearth)

Density: 0.70 g/cm3 (lighter than water!) Rotation Period: 10.66 hours Tilt of Axis: 26.7o Surface Temperature: 103 K (-274o F)

Physical Data Orbital Semi-Major Axis: 9.54 AU Orbital Period: 29.46 years Orbital Inclination: 2.5o

Orbital Eccentricity: 0.056 Surface Gravity: 1.17 Earth gravity Satellites: 60 as of 2011 Magnetic Field: yes

Saturn’s Interior

METALLICHYDROGEN

ATMOSPHERE

LIQUIDMOLECULAR HYDROGEN

Outer three layers are similar to Jupiter’s

The exact composition of the core of Saturn is still unknown

ROCK?

ICE?

Saturn’s Atmosphere 94% Hydrogen 6% Helium Small amounts of:

MethaneAmmoniaPhosphineEthaneAcetylene

Saturn’s Atmosphere

Composed of methane and ammonia

Saturn is surrounded by an orange haze which masks the cloud -top features

Saturns belts are therefore less noticeable

CLOUDS:

False color image shows Saturn’s bands

Saturn’s Atmosphere

WINDS: Unlike Jupiter, all go in the same direction

(east) The equatorial jet reaches speeds of 1,100

mph! (Fastest winds on Jupiter are 335 mph)

Saturn’s AtmosphereFEATURES: Ovals - cyclonic

features like Great Red Spot on Jupiter

They don’t last long Biggest ovals seen

on Saturn are only 1/10 as big as the Great Red Spot

The White Spot of 1994

Saturn’s Atmosphere

Hot Surface Temperature: Like Jupiter, Saturn radiates 2.5x as much

heat as it receives from the Sun Saturn is two times farther away from the

Sun than Jupiter, and receives 1/4 as much sun light, so Saturn’s interior is less hot

Saturn’s internal heat is due to heavy element diffusing toward the interior

Saturn’s Magnetic Field

Detected by Pioneer spacecraft Between the size of Earth and Jupiter’s

magnetic field (0.5 Gauss) Magnetic axis is almost aligned with

rotation axis (0.7o tilt)

Saturn’s Rotation Periods

Differential rotator like Jupiter Rotation Period is 10h02m at equator Rotation Period is 1 hour longer at 60o

latitude Radio Period: 10h39m22s

Spin so fast, Saturn is very oblate (flat)

Saturn’s Ring System

There is a gap between the A and B ring called “Cassini’s Division”

Ring particles are made of mostly ice

Average particle size is about 10 meters

BAFGE C D

CASSINI’S DIVISION

SATURN

Saturn’s Ring System

Spokes: Magnetically levitated

dust which is rotating with the magnetic field

This dust is about the size of cigar smoke

m

Saturn’s Ring System

Shepherd Satellites: Small moons in the

rings gravitationally interact with wandering ring particles and return them to the ring, thus preserving the ring.

Shepherd Satellites Prometheus and Pandora sheperding the F ring

Saturn’s Moons A total of 18 have been discovered thus far

Co-Orbital Satellites: As a trailing co-orbital satellite overtakes

the leading satellite, they gravitational forces make the moons trade places

1 2 3 4 5

Saturn’s MoonsTITAN: Saturn’s largest moon Only 2% smaller than

Ganymede, so is the second largest moon in the solar system

Has a thick nitrogen atmosphere

Surface Pressure: 1.6 atm

Saturn’s Moons

MIMAS: Has an impact crater

that is 1/3 the diameter of the satellite

Biggest impact Mimas could have taken and still survived

Saturn’s MoonsPHEOBE: Discovered in 1898 First retrograde

satellite known in the solar system

Most likely a captured satellite

Saturn’s outermost moon

Saturn’s MoonsIapetus: Is sweeping dark dust

from Pheobe Like most moon it is

in synchronous rotation

It’s leading face is therefore 5x dimmer than its trailing face

Saturn’s Moons

Hyperion: Only satellite in the

solar system that is not in synchronous orbit

Not spherical It is the sixteenth

moon out and is 286 km in diameter