Planetary Geology Seminar lecture - Uranus & Neptune
11/12/98 - H. D. Maher Jr.
Uranus: moons characterized
by diversity independent of size and position. Why?
- small 470 km in diameter, yet very complex surface, bimodal
- amazing image of fault scarps, all normal, indicates
global expansion. Why concentrated into one rift system and not distributed?
- distinctive V-shaped fracture patterns.
- inhomogenous and incomplete differentiation.
- energy source? past resonance?
- much more resurfacing, global graben system, flows.
- ammonia and water-ice crust.
- unusual crater size distribution
- source of energy?
- crater distribution that is similar to lunar highlands,
lack of tectonic activity.
- darkest of moons (aging process)
- largest moon, half the earth's moon, similar in Oberon
in size but quite different in terms of surface appearance.
- fewer and smaller craters than Umbriel and Oberon, more
- near global network of grabens with relief of 2-5 km.
Younger than most of the cratering.
- crater saturation, up to 100 km size, similar to lunar
Neptune: also has ring system,
far fewer satellites.
- comparable in size to earth's moon and to Io
- methane and N2 ices identified at surface, no evidence
of water-ice yet.
- unusual orbital parameters.
- polar ice cap, global fracture system (triple bands?),
- crater density similar to that of Lunar Maria, smooth
- eruption plumes of active volcanoes, geysers? Sublimation
T of N2 pretty low!
Below are photos of a fault scarp 2-5 km high on tiny Miranda!
Once again, diversity of surface activity on these outer
moons is surprising.