astro moons

Galileans to Scale: 

Galileans to Scale

Interiors of the Galileans: 

Interiors of the Galileans

Overview of Surfaces: 

Overview of Surfaces

Outer Galilean Moons: 

Outer Galilean Moons Callisto: Moderately dark surface Heavily cratered No magnetic field ~1/4 of interior is ice (by mass) Ganymede: Moderately bright surface Weak magnetic field and evidence for a denser core Perhaps melted in past to allow for differentiation

Callisto Terrain: 

Callisto Terrain

Ganymede Terrain: 

Ganymede Terrain

Inner Galilean Moons: 

Inner Galilean Moons Europa: Bright surface Absence of craters – young surface Possible mag. Field and denser core Surface ice is a thin layer (100’s of meters) floating on H2O ocean(!) – requires a source of heating Io: Rocky interior Orbits inside Jupiter’s magnetosphere Io is tidally heated and volcanically active (predicted in 1979 and discovered by Voyager 1 in same year) Surrounded by a yellow Na-cloud

Europa Terrain: 

Europa Terrain

Crater on Europa: 

Crater on Europa

Close-up on Euorpa: 

Close-up on Euorpa

Subsurface Model: 

Subsurface Model

Example Volcanic Activity: 

Example Volcanic Activity

Volcanic Eruption at Io: 

Volcanic Eruption at Io

Io’s Sodium Cloud: 

Io’s Sodium Cloud

Sulphur Ring of Io: 

Sulphur Ring of Io

Orbital Resonances: 

Orbital Resonances

Titan: 

Titan 1944 – Kuiper discovers a thick atmosphere Atm. is a reddish, featureless haze; mainly N2 with 10% CH4 and smog: Psurf=1.6PE and Tair=93 K (-292oF) Only satellite with a thick atm.: CH4 rain, snow, and ice? Pools of liquid N2 and CH4? 2004 – Cassini probe called Huygens will parachute into Titan’s atm.

Titan to Scale: 

Titan to Scale

Impression of View of Saturn from above Titan: 

Impression of View of Saturn from above Titan

Surface of Titan: 

Surface of Titan

Earth-Titan Comparison: 

Earth-Titan Comparison

The Active Atmosphere of Titan: 

The Active Atmosphere of Titan

Huygens Probe at Titan: 

Huygens Probe at Titan

Cold Geysers at Enceladus: 

Cold Geysers at Enceladus

The Geyser Model: 

The Geyser Model

Mimas: 

Mimas

The Impact at Mimas: 

The Impact at Mimas Diameter ~ 390 km Huge crater from impact, almost big enough to shatter this moon Estimate: Binding Energy of Mimas Kinetic Energy of Collider Mass and Size of Collider m v M D rH2O

Moons of Uranus: 

Moons of Uranus Umbriel and Oberon Heavily cratered Large cracks Ariel and Titania Lighter cratering Resurfacing by flows of volcanic water (!) Some regions of Ariel are featureless - very recent! System of deep cracks (tidal heating effects?) Miranda Rolling and cratered terrain Some fractures 20 km cliff - takes 10 min to fall (in contrast to 1 min as at Earth)

Moons of Uranus: 

Moons of Uranus

Miranda: 

Miranda

Triton: 

Triton Triton is the only large moon with a retrograde orbit (possibly a captured body?) Tidal bulges on Neptune lag instead of lead Triton Orbit is degrading Will eventually shatter as nears Roche Limit (in ~109 years to make a ring to rival Sat.) Composition: 75% rock, 25% ice Atm.: thin N2 Polar Capts: N and CH4 ices Evidence for resurfacing and interal activity, even geyser eruptions of N gas, leading to sooty plumes

Triton: 

Triton

The Tides at Triton: 

The Tides at Triton