The Jovian Planets,
Part II
Saturn
SATURN
The 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
o
 Tilt of Axis: 26.7
o
 Surface Temperature: 103 K (-274 F)
Physical Data
 Orbital
Semi-Major Axis: 9.54 AU
 Orbital Period: 29.46 years
o
 Orbital Inclination: 2.5
 Orbital Eccentricity: 0.056
 Surface Gravity: 1.17 Earth gravity
 Satellites: 60 as of 2011
 Magnetic Field: yes
Saturn’s Interior
ATMOSPHERE
 Outer
three layers
are similar to
Jupiter’s
 The exact
composition of the
core of Saturn is
still unknown
LIQUID
MOLECULAR HYDROGEN
METALLIC
HYDROGEN
ICE?
ROCK?
Saturn’s Atmosphere
 94%
Hydrogen
 6% Helium
 Small amounts of:
Methane
Ammonia
Phosphine
Ethane
Acetylene
Saturn’s Atmosphere
CLOUDS:
 Composed of methane
and ammonia
 Saturn is surrounded
by an orange haze
which masks the cloud
-top features
 Saturns belts are
therefore less
noticeable
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 Atmosphere
FEATURES:
 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
o
rotation axis (0.7 tilt)
Saturn’s Rotation Periods
 Differential
rotator like Jupiter
 Rotation Period is 10h02m at equator
o
 Rotation Period is 1 hour longer at 60
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

CASSINI’S DIVISION
SATURN
E
G
F
A
B C D
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 Moons
TITAN:
 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 Moons
PHEOBE:
 Discovered in 1898
 First retrograde
satellite known in the
solar system
 Most likely a captured
satellite
 Saturn’s outermost
moon
Saturn’s Moons
Iapetus:
 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