(Linked image from The Cosmic Perspective [Addison Wesley Longman])
| Lecture |
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| Moons of the Giant Planets
(Linked image from The Cosmic Perspective [Addison Wesley Longman]) |
After listening to the lecture, finishing the "Moons of the Giant Planets" lab, reading these on-line notes (including the sections on tidal heating), you should be able to
Describe at least two surface peculiarities of Neptune's moon Triton, and give possible reasons for these peculiarities.
Summarize the two theories of why Miranda, a small moon of Uranus, has such strange features, most seen nowhere else in the solar system.
Contrast the characteristics of an "irregular satellite" with those of a "regular satellite," including possible origins and orbits.
Outline why Saturn's moon Titan is of such interest to scientists.
Summarize possible scenarios for the resurfacing of Enceladus and Dione, moons of Saturn.
List two distinguishing features of each of the 4 Galilean moons of Jupiter.
Explain how tidal heating of Io and Europa--the innermost 2 Galilean moons--works.
Define "orbital resonance" and give an example.
Explain how Jupiter and the 4 Galilean moons can be considered a miniature solar system, addressing both the characteristics of the moons and their orbits.
List the 3 criteria needed to have tidal heating.
Take the Quiz!
Neptune's Moons
Triton from Views of the
Solar System (for lots of information, small videos, etc.)
Triton, true to its name (a mythological god with a human torso and a fish's tail), has two distinct parts. One hemisphere resembles a "cantaloupe" with closed depressions 30-50 km wide that are separated by ridges. Could this be the result of blobs of material rising from depth?
Triton's southern hemisphere is active! Voyager images plumes of sublimated nitrogen that reached heights of 8 km, and that were blown laterally for several hundred km. Triton has an extremely tenuous atmosphere that has winds. Could the cause of these plumes be solar heating of a thin frozen nitrogen layer? Melting of volatiles near the surface by internal heat?
Triton underwent extreme tidal heating during the process of being captured by Neptune. Its orbit was intially very eccentric and gradually circularized. During the early stages, as it came close to Neptune it was stretched. When it was far away, it relaxed. This kneading creates internal heat (see discussion on Io). Triton orbits retrograde and will eventually collide with Neptune or else be tidally torn apart as its orbit eventually degrades.
Triton is very similar to Pluto in size and composition. Could it be a Kuiper Belt object that was captured by Neptune billions of years ago?
The large moons of Uranus are a mixture of ice and rock. On first glance, they look fairly homogeneous and non-descriptive. But, upon closer review, they show a horrendous, tormented childhood. These moons appear to have undergone extensive faulting and resurfacing along with the cratering.
Miranda from Views
Miranda is the weirdest moon of the solar system. It is a "mishmash" of terrains. Two theories have tried to explain Miranda's surface. One supposes that Miranda suffered a tremendous hit that nearly broke the moon apart. It regathered the pieces to make a moon. The other (more widely accepted) theory states that Miranda was caught in the process of differentiating, and experienced a huge upwelling of partially melted ice that froze into the present day configuration.
Ariel from Views
Ariel is
similar to Uranus' moon Titania. All of Uranus's large moons are a mixture of
ice and rock. They all have varying degrees of cratering and huge valleys. Most
of the moons have been resurfaced, inferring substantial heating at on time.
See Enceladus, Dione, Rhea, Iapetus, Mimas, Titan from Views of the Solar System
The Cassini Mission and its probe, Huygen's, will be arriving at the Saturnian system in July of 2004. Cassini will do for Saturn and its rings and moons what Galileo did for Jupiter and its rings and moons. What discoveries are in store for us?
What we do know at the present about Titan is that its atmospheric pressure at its surface is 1.5 that of Earth's. Its atmosphere is composed of molecular nitrogen. Its surface is thought to have a mixture of "continents and seas," with the seas maybe made up of liquide methane. What else is in Titan's atmosphere? Argon, methane, ethane, hydrogen cyanide (always pleasant), CO2, H2O, plus additional compounds. It is thought that the present conditions on Titan mimic those of the early, early Earth.
Of enormous interest (and containing much more information than could be put into a whole quarter's worth of lectures): Galileo: Journey to Jupiter. This resource was the basis for most of the images and information given in class.
Also see Io, Europa, Ganymede, Callisto from Views of the Solar System for a large number of images and cool videos (mpeg, avi, mov, etc.)
Ancient, battered surface
May have a huge salty ocean beneath the surface
Generates own magnetic field that varies in response to Jupiter's magnetic field as Callisto orbits Jupiter
You will be getting up close and personal with Europa with the activity or paper (depending on the quarter's requirements). Be sure to notice the following features:
Europa is heated by the same mechanism as Io (which follows): tidal heating.
Be sure to take a look at the volcanoes (geysers) on Io, and all of the differently colored features of its surface.
orbital resonances
of Io, Europa, and Ganymede.
The Jovian System: a Miniature Solar System
The Galilean moons form a mini-solar system at Jupiter. Evidence that Jupiter
must have radiated considerable heat during its formation.
Galileo's Io Information, including lots of images.
Galileo's Europa Information, including lots of images.
Galileo's Information on Ganymede, including new discoveries
Galileo's Discoveries at Callisto, the oldest body in the solar system.
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