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Amazing Saturn
●Saturn from the ground
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Saturn Information Overload
●The Cassini Mission started orbiting Saturn in 2004.
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Getting There
●Planetary pinball with passes by Venus, Venus, Earth, and Jupiter to pick up speed.
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Saturn Information Overload●The orbiter includes imaging, radar, particle and field experiments and a probe that was dropped onto Saturn's largest moon, Titan.
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Saturn Information Overload●Orbit after orbit its has provided a firehose of information about Saturn, its rings, and its Moons.
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Infrared image showing that Saturn, like Jupiter radiates internal energy in excess of the Sun's input.
It should have cooled off by now however.
It is likely that differentiation of helium toward the center of Saturn is generating mechanical energy.
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Saturn's Rings●Saturn's rings consist of a myriad of particles of relatively pure water ice with sizes ranging from from snowflakes to mountains (and moons).
● All combined the material amounts to no more than a tiny moon's worth of ice.
● The rings likely originated via the disruption (via impact?) of a small icy satellite.
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The Roche Limit and Planetary Rings
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Consistent tugs from satellites clear out gaps.
Mimas maintains the Cassini Division (the most apparent large gap).
A particle in the Cassini Division orbits Saturn twice for every one orbit of Mimas.
Mimas
Substructure in Saturn's Rings
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Mimas
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Satellites can directly create gaps and shape rings as well.
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21●Tenuous outer rings formed by erosion and, in the case of Enceladus, cryovolcanic activity.
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Erosion of Phoebe by impacts generates (temporary) ring particles that strike and modify Iapetus.
23●These particles are evident via their mid-infrared blackbody glow, despite being only 90K (-300F)
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Big Icy Satellites
Rhea
Dione
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Big Icy Satellites
Tethys
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Equatorial Ridge
Voyager Mountains
Iapetus
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Hyperion
Janus
Dozens of Small Icy Satellites
Telesto
Epimetheus
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Hyperion
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Phoebe
Orbits Saturn backwards
Source of its own diffuse ring
Is it a captured“comet”/Kuiper BeltObject?
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An inner moon of Saturn.
The most reflective object in the solar system.
Brighter than snow!
Both “young” and “old” terrain
Enceladus
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The Plumes of Enceladus
● Water vapor and ice particles launched at speeds high enough to escape.
● Liquid water inside Enceladus??– Tidal heating (a little)
– Radioactive heating (maybe)
– Water-ammonia mixture (possible)
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A World Too Small for Volcanism?
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Enceladus to Scale●
Enceladus
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The south pole cracks, which are the source of the jets, are warmer than their surroundings.
The boxes give temperature in Kelvins – so about -300F.
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Warm Eruption Sites
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A Potential (unexpected) Habitat
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Titan●Titan is the second largest moon in the Solar System and bigger than the planet Mercury.
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A Chemistry Laboratory● Titan has a thick, primarily nitrogen, atmosphere with a surface pressure 1.5 times that of Earth.– The atmosphere contains traces of methane and ethane as well as other organic molecules.
– Ultraviolet sunlight breaks these molecules apart and they reassemble into even more complex molecules.
● The atmosphere is filled with organic particle smog that hides the surface at visible wavelengths
– Larger molecules and particles filter down and collect on the moon's surface.
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A Thick Smoggy Nitrogen Atmosphere
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Peering through the Smog at Titan
● Small particles block short wavelength light but permit longer wavelengths to pass.– Sunsets are red for this reason. Red light penetrates the atmosphere better than blue.
Visible Infrared
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●A relatively crater free surface– resurfaced by weather and cryovolcanism.
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Clouds and (methane) Rain on Titan
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Springtime Weather on Titan
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Lakes and Erosion on Titan
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Lakes and Erosion on Titan
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Lakes and Erosion on Titan
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Lakes and Erosion on Titan
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Visiting Titan's Surface – The Huygens Probe
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Visiting Titan's Surface – The Huygens Probe
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Visiting Titan's Surface – The Huygens Probe
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Visiting Titan's Surface – The Huygens Probe
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Visiting Titan's Surface – The Huygens Probe
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The Surface of Titan
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Atmospheric Composition
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Things to Know About Saturn
●Saturn has the same types of clouds as on Jupiter but lower in the atmosphere (thus harder to see).
●Saturn's rings are made of nearly pure water ice chunks– kept apart by Saturn's gravity (Roche Limit)
– gaps cleared by tugs from Moons
●Titan is the 2nd largest moon in the Solar System– It has a thick nitrogen atmosphere
– Methane/ethane are trace gasses that forms clouds and produce rain.● The surface is eroded by the “weather”
– Solar ultraviolet radiation forms an organic smog, coating the surface with pre-biotic chemical compounds.
●Enceladus, a tiny moon, has water geysers that spray material out to form Saturn's E-ring.
● Subsurface water means prospects for life!
