Ring World

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Ring World
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Mass

• Earth Saturn
• 1 95.2
• (x 1024 kg) 5.97 568

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Size

• Earth Saturn
• Radius 1 9.45
• Equatorial 6378 60,268
• Polar 6357 54,364
• Oblateness 0.3 9.8
• Look for the flattening in the next photo.

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Density

• Earth Saturn
• 100 12.5
• kg/m3 5515 687
• Saturn has the lowest density of all the planets
  and moons.
• Saturn would float in water!

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Large Magnetosphere

• Saturns magnetosphere is about 1/5th as large as
  Jupiters.
• This is expected because Saturn has a thinner
  conducting mantle of metallic H than Jupiter has.
• Its 20x weaker than Jupiters field.
• Its actually only 68 as strong as Earths!

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Magnetosphere

• Jupiters magnetosphere is tipped slightly to its
  rotation, and is complex in structure
• Saturns magnetosphere is aligned almost
  perfectly with its rotation (axisymmetric), and
  its structure is very simple.
• Interesting feature a ring current.

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Evidence for Saturns Magnetic Field!
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Equatorial Ring Current

• Saturns moons Enceladus, Dione, and Tethys are
  enclosed in a torus of ions (like Jupiters Io).
• This torus is outside the major rings (but inside
  the thin, tenuous E ring).
• A current of about 10 million amps flows through
  this outer ring.

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Chemical Composition

• 96.3 H 3.25 He (by volume)
• Traces of methane (CH4), ammonia (NH3), water,
  ammonium hydrosulfide (NH4SH)
• Like Jupiter, there is a mantle of metallic H
  under a gaseous H envelope.
• Rocky / metallic core

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Saturns Orbit

• Average distance from the sun
• 1.43 billion km (9.6 A.U.)
• Perihelion 1.35 billion km
• Aphelion 1.51 billion km
• Orbit Eccentricity 0.056 (slightly more
  eccentric than Jupiters orbit)

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Orbit (2)

• Orbital Period 29.5 years
• Orbital Velocity 9.7 km/s
• Inclination of orbit to ecliptic 2.5o

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Saturns Rotation

• Rotational Period 10.66 hours (10h 40m)
• Saturn has zonal winds, like Jupiter, but the
  colors are more muted.
• The rotational axis is tilted 26.7o to the
  ecliptic. This makes for a periodic tilt in the
  rings as viewed from the earth.

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Notice the rotational storm.
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A red oval similar to Jupiters GRS.
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The Rings !

• 2 (3) rings visible to the naked eye.
• separated by visible gaps.
• 3 more rings visible telescopically
• A new ring appears to be forming!

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Pan orbits within the Encke Division
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Movie
Dusty ring spokes
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Rings are Dynamic, not Static

• Dusty spokes indicate that the rings may be able
  to change on a short time frame.
• There are also periodic ripples in part of the
  ringsevidence of a collision between the rings
  a comet or asteroid.

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BraidedF ring The ring isnt
really braided, but has spirals around it.
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Shepherd Moons

• Collisions between ring particles should remove
  kinetic energy from some particles, transfer
  kinetic energy to others.
• Slower particles should fall into Saturn.
• Faster particles should leave the ring.
• Net the rings should spread out and dissipate.

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The gravity of the shepherd moons focuses
the rings.
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Heres a site with more info about the
spiral around the F ring.
http//www.aim.ufr-physique.univ-paris7.fr/CHARNOZ
/homepage/SPIRAL/spiral_uk.htm
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Barely discernible new ring (with 2 new tiny
moons)
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The Larger Moons

• Theyre all ice balls, but theyre not all the
  same.
• Mimas Enceladus Tethys
• Dione Rhea Titan
• Iapetus
• All of these moons are in synchronous rotation
  (leading vs. trailing hemisphere differences)

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Mimas with HerschelCrater Mimas is about
the size of Ohio 1150 kg/m3
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Geysers of water water vapor erupt
fromEnceladus south pole region. Hot spots
have been discovered here by Cassini.
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Tethys has a gigantic canyon which nearly circles
the moon. Ithaca Chasma
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Dione, leading hemisphereat left, trailing at
right.
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Dione
Direction of movement through space.
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Rhea
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Rhea also has those strange lighter stripes on
its trailing hemisphere.
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Atmosphere of N2heavily laden with hydrocarbons
methane ethane Very smoggy
Titan 5150 km diameter 1880 kg/m3Ganymede
5262 km dia. 1940 kg/m3How can Titan have a
thick atmosphere, when Ganymede doesnt?
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Titan has a complex layered atmosphere
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Titans atmosphere is 95 N2, 10X denser
than Earths, and extends 600 km above the
surface.
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Some liquid flows on titans surface.
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Is that the shoreline of an ethane lake or a
basalt plain?
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The darker areas are being interpreted as
lakes of liquid ethane or methane. (Not yet
confirmed)
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At Titans surface, the Temperature is about 95K
(-290oF)
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Iapetus sooty leading hemisphere bright trailing
hemisphere equatorial ridge
Whats the source of the soot?
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Missions to Saturn

• Pioneer 11
• Launched 1973, flyby 1979.
• Transmitted low-resolution photos of Saturn,
  rings, moons.
• Voyager 1
• Launched 1977, flyby 1980
• Transmitted 900 photos of the moons.
• Discovered complexity of rings nature of
  Titans atmosphere.

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Missions to Saturn (2)

• Voyager 2
• Launched 1977, flyby 1981
• 1150 photographs of the moons
• Cassini Orbiter with Huygens probe to Titans
  surface.
• Launched 1997, arrived in orbit July 1, 2004.

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Cassinis Mission

• Cassini is designed to photograph and map Saturn
  its moons in visible, infrared, and ultraviolet
  wavelengths.
• It has a magnetometer, magnetic imager, and
  plasma imager to closely study Saturns magnetic
  field.
• Huygens probe landed on Titan on January 14, 2005.

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