[X] My Assistant

[exoplanet]

My first post a few months ago received no reply. I highly suspect that the "craters" that have been imaged on Titan are most likely volcanic calderas and very, very, active. I have found a photo taken from Gallileo showing similar serpentine channels that are found on Io that are as well found on Titan (only these are lava channels on Io):

http://www.spaceref.com/news/viewpr.html?pid=6859

Curious to know what you all think???

I think that Titan might surprisingly be a very geologically active world. If so, what would be creating the internal heat???

[Guest_BruceMoomaw_*]

Actually, Bruce Bills and Francis Nimmo have speculated that the very significant and puzzling eccentricity of Titan's orbit -- several percent; much higher than Io's -- is being maintained by resonant gravitational tuggings which come in Titan's case not from Saturn's other moons, but from Jupiter itself during its periodic close encounters with Saturn. (This is supposedly happening to Titan -- rather than to Saturn's other moons -- because it's at just the right distance from Saturn for the rate at which the long axis of its elliptical orbit precesses around the planet to be roughly in sync with Jupiter's flybys of Saturn.)
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1341.pdf

They haven't worked out all the details of this theory yet, but it seems to me to fit the now-known facts better than any other so far. This high orbital eccentricity of Titan has worried scientists for decades. The only alternative theories for it they've been able to develop are (1) that Titan recently got walloped by a really gigantic impact that knocked its orbit askew (which I think Cassini's surface observations have now ruled out); or (2) that Titan is so internally rigid that it undergoes very little surface flexing despite the considerable changes in the force of Saturn's gravity on it (which was getting hard to justify geologically even before the new evidence that Titan has a substantial subsurface liquid layer).

If Bills and Nimmo are right, then Titan really is a strange, cryogenic analog of Io -- but with its volcanoes being tidally driven by Jupiter itself rather than by Europa and Ganymede. (Of course, we already know -- thanks to Huygens -- that Titan is a strange, cryogenic analog of the southwest American desert, complete with flash floods, arroyos and playas.)

I find myself wondering whether similar periodic interactions with Jupiter, changing over geologic time as Saturn's moons slowly move outwards from the planet, might also be responsible for such things as Enceladus' apparent periodic bouts of strong tidal heating (rather than Dione being responsible for these), the Keck Telescope's observations suggesting that Tethys may also have some geyser activity on it spewing particles into the E Ring (albeit currently weaker than Enceladus' activity), and maybe even the sizable eccentricity of Mimas' orbit, which seems to me as odd as that of Titan's orbit. (Is it possible that Mimas has only recently been forced into that degree of orbital eccentricity for the first time, and hasn't yet undergone enough tidal heating to start producing surface geological activity and geysers of its own?)