Earth Comparison
orbit: 9.5 AU
planet diameter: 9.5 Earths
mass: 95 Earths
God of agriculture
Related to Greek God, Cronus
Known since prehistoric times
1610, Galileo noted its odd appearance but was confused
1659 Christian Huygens correctly inferred the geometry of the rings
Visiting Spacecraft
Pioneer 11, 1979 flyby
Voyager 1, 1980 flyby
Voyager 2, 1981 flyby
Cassini arrived on July 1, 2004 will orbit for at least four years
Planet Shape
Visibly flattened (oblate)
Equatorial and polar diameters vary by almost 10%
Result of rapid rotation fluid state
All gas planets are oblate, but not as much
Least dense of planets; density is 70% of water
75% hydrogen
25% helium
Traces of water, methane, ammonia, and rock
similar to solar nebula from which the solar system was formed
interior is similar to Jupiter's; rocky core, liquid metallic hydrogen layer, molecular hydrogen layer
Interior is hot (12000 K at the core)
Radiates more energy into space than it receives from the sun
Equatorial bands are fainter and wider on Saturn than Jupiter
Long lived ovals and other features in common with Jupiter
1990, HST observed an enormous white cloud near Saturn's equator
1994, a smaller storm was observed
South Pole Storm
Ring System
Rings reflect up to 60% of the light they receive
Composed of small particles each in an independent orbit
Water ice and rocky particles with icy coatings
Range in size from a centimeter to several meters
A few kilometer-sized objects are also likely
Extraordinarily thin
250,000 km or more in diameter
Less than one kilometer thick
If compressed into a single body it would be no more than 100 km across
Ring System Order
D- Ring
Guerin Division
C- Ring
Maxwell Division
B- Ring
Cassini Division
Huygens Gap
A- Ring
Encke Minima
Encke Division
Keeler Gap
F- Ring
G- Ring
E- Ring
Ring System Facts
Three main rings can easily be seen from Earth
A= bright
B= bright
C= faint (seen in front of saturn)
D- Ring
-complex structure made up of several smaller rings where "knots" are visible
-clumps of ring material or mini moons apparent
-braided appearance
-shepherding satellites
-complex tidal resonance between some moons and ring system
-Atlas, prometheus and pandora help keep rings in place
-Mimas is responsible for the Cassini division
-Pan is located inside the Encke Division
-S/2005 S1 is in the center of the Keeler Gap
-System is very complex and as yet poorly understood
-Pandora, F-Ring (artist)
-R/2004 S1 Ring&Atlas
Ring Spokes
Puzzling radial inhomogeneities in the rings called "spokes" seen by Voyagers and Cassini
Ring Origin
Origin of rings is unknown
Not stable and must be regenerated by ongoing processes
Current rings only a few hundred million years old
Magnetic Field
Significant magnetic field
Aurora as well
Ring Crossings
Saturn Satellites
56 discovered, 35 names
Tethys, Talesto, and Calypso
Larger Than Mercury and Pluto
1/2 water ice, 1/2 rocky material
Only satellite in solar system with significant atmosphere (1.5 times that of Earth)- 94% Nitrogen, 6% Argon
Very similar to the early Earth
Surface is 94K (-290F)
Surface covered by liquid methane lakes
The Huygens probe landed in January of 2005