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Saturn
•Slightly smaller
•1/3 the mass
•density
700 kg/m3
Interior - light elements,
lack of rocky materials
Intro to Solar System
Saturn and Outer Planets
Voyager 2, NASA
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Saturn - Atmosphere
•belts - driven by rapid rotation
•period - 10 hrs 14 min
•storms at intervals of 30 years
•mostly H, He, some methane, water vapor,
ammonia
•clouds - less colorful than Jupiter, yellow and
orange
•winds 500 m/s near equator
Intro to Solar System
Saturn and Outer Planets
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Saturn - Interior
Composition - much like Jupiter
maybe a small, rocky core OR no core
at all
large zone of liquid hydrogen
smaller one of metallic liquid hydrogen
Saturn emits more energy than it receives
from the Sun - leftover from formation
Intro to Solar System
Saturn and Outer Planets
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Voyager 1, JPL, NASA
Moons and Rings
at least 18 moons
densities 1200 - 1900
kg/m3
Titan: largest
Mimas, Enceladus, Tethys, Dione,
Rhea, Iapetus
moons: mostly ice (60 - 70%)
some rocks (30 - 40%)
Intro to Solar System
Saturn and Outer Planets
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Titan
50% ice, 50% rock
atmosphere - 80% molecular nitrogen
(sound familiar?)
pressure - 1.5 atm
Voyager - orange smog layer, blue at
edges => atmosphere varies in
composition
model: surface covered with a frozen ocean
of ethane, methane, nitrogen, below that a
layer of acetylene
Intro to Solar System
Saturn and Outer Planets
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Voyager 2, JPL, NASA
Moons and Rings
rotation speeds of rings
follow Kepler’s Third Law
the closer they are to Saturn,
the faster they rotate
=> the rings are made
of separate particles
Enceladus
Intro to Solar System
Saturn and Outer Planets
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Ring System
ring particles: water ice, rocky particles
covered with ice
size of golf balls to the size of a house
Saturn’s crowning glory - the rings
Intro to Solar System
Saturn and Outer Planets
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Uranus
Voyager 2, NASA
Intro to Solar System
Saturn and Outer Planets
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Uranus
•upper atmosphere 58 K
•mostly molecular H and He
•bluish green - sunlight scattered by the
atmosphere - methane
•ammonia clouds, banded structure
•rotation axis almost in plane of orbit
•density 1300 kg/m3
Intro to Solar System
Saturn and Outer Planets
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Uranus Composition
15 % H, He
60 % ices - water, methane, ammonia
25% silicates and iron
may have a small icy-rock core encased
in an icy or watery mantle
Intro to Solar System
Saturn and Outer Planets
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Moons and Rings
5 major moons: Miranda, Ariel, Umbriel,
Titania, Oberon
surfaces appear to be dirty ice
Intro to Solar System
Saturn and Outer Planets
11
Voyager 2, JPL, NASA
Miranda: many types of terrain, jumbled
together - grooved regions, faults,
cliffs
strangest surface in the Solar System
Intro to Solar System
Saturn and Outer Planets
12
Rings
rings discovered accidently
rings have low albedo - 0.05
dark carbon material,
probably no ice
Erich Karkoschka, University of Arizona
Lunar & Planetary Lab, NASA
magnetic field is tipped 59o with respect
to rotation axis
Intro to Solar System
Saturn and Outer Planets
13
Neptune
• discovered by
gravitational
effects
• orbits in 165 years
• bluish color methane
• molecular H and He
• cloud bands
• temperature 60 K
Intro to Solar System
Saturn and Outer Planets
Voyager Project, NASA
14
Neptune - Atmosphere
Great Dark Spot
storm 30,000 km across
region of high pressure
bright, cirrus-like clouds, condensed methane
no complex swirls seen
magnetic field - tilted 47o from rotation axis
Intro to Solar System
Saturn and Outer Planets
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Moons and Rings
Triton
largest
retrograde orbit
tidally locked
very thin atmosphere,
mostly nitrogen with
trace methane
APOD
Intro to Solar System
Saturn and Outer Planets
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Triton
not too heavily cratered
surface relatively young, recently modified
temperature 37 K
atmosphere - mostly nitrogen, trace
of methane
erupting geyser!
2100 kg/m3 => rocky core surrounded by
a mantle of methane and water ice
Intro to Solar System
Saturn and Outer Planets
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Pluto and Charon
discovered by tedious searching of
photographic plates
39 AU from the Sun, now is orbiting
closer than Neptune
methane coated ice surface
temperature 60 K
nitrogen and CO ices
rotation period 6.4 days
atmosphere - N, CO, methane
Intro to Solar System
Saturn and Outer Planets
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Charon - Moon
or Double Planet?
smaller than Pluto - 1200 km diameter,
Pluto 2300 km
synchronous rotation
can use Charon to calculate the mass
of Pluto ( now how do you do that?)
average density together is 2000 kg/m3
Pluto is 75% rocky materials
Intro to Solar System
Saturn and Outer Planets
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Charon
water frost on surface, could be icy
materials totally
could these be moons of Neptune’s
that escaped?
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Saturn and Outer Planets
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