Geology Reference
In-Depth Information
crater, Herschel. At 1,048 km in diameter, Tethys is about
twice the size of Mimas and also has extensive canyon
systems, most notably the 2,000 km long Ithaca Chasma.
It, too, might have formed in response to an enormous
impact (resulting in Odysseus crater).
Some of Saturn
s hallmark ring system in the
early 1600s. Subsequent telescopic observations and
spacecraft data show that the system is highly complex,
featuring interactions with many of Saturn
'
s moons. Rings
consist mostly of water-ice grains that range in size from
dust to boulders. The various ring elements are designated
by letters that indicate their sequence of discovery, not
their distance from Saturn. For example, the A Ring is the
outermost large, bright ring, while the F Ring was discov-
ered through Pioneer observations and is bounded by two
small moons that seem to keep the ring particles within a
very narrow band. Current models suggest that most of the
rings were generated by the tidal breakup of one or more
satellites.
Galileo discovered Saturn
'
s moons show contrasting bright and
dark hemispheres. For example, Iapetus has a very dark
leading hemisphere and a bright trailing hemisphere, with
a gradational boundary between the two. The difference is
commonly attributed to the formation of a dark lag deposit
of carbonaceous material left on the surface after subli-
mation of an icy matrix. Additional dark material might be
implanted from dust derived from the neighboring moon,
Phoebe.
'
Assignments
1.
Construct one or more graphs of Saturn
s moons to
assess potential relationships among satellite density,
diameter, orbital distance from Saturn, retrograde ver-
sus prograde orbit, and geologic characteristics, and
then discuss the results.
'
related to differences in gravity between Rhea and
Iapetus.
4.
Some of Saturn
'
s moons have distinctive differences in
albedo from one part of the satellite to other parts of the
surface. Explain how these differences might originate.
2.
Compare and contrast the tectonic features seen on
Mimas and Tethys.
5.
Discuss briefly the relationships between the satellites
of Saturn and the various rings.
3.
Rhea and Iapetus have about the same diameter, but
their densities are different. Examine images of
these two moons and identify a crater that is of
equal size on each. Compare their morphologies
and explain any differences between the two as
6.
Examine images of Titan
'
s dunes and discuss the
differences and similarities with dunes seen on Venus
and Mars in terms of sizes, morphologies, and inferred
directions of formative winds.
