[X] My Assistant

[Palomar]

Best evidence yet

*...for a shoreline on Titan; they're calling it "dramatic." Area measures 1,060 by 106 miles. Is from Cassini radar, obtained during the latest flyby. Speculation continues regarding seepage of liquid from the ground/ground springs and/or rainfall.

[Guest_BruceMoomaw_*]

Actually, I believe you're right -- on thinking more about it, I believe that I have more provided an explanation for why Titan MAY be the way it so far appears to be to Cassini, rather than an explanation for why it MUST be that way.

The fact that both the evaporation and precipitation rates of liquid methane on Titan must be very slow does not in itself provide any reason to think that there couldn't be large bodies of liquid methane actually on the surface. And -- aside from the radar maps so far -- the only evidence we have that there are not large surface seas of liquid methane is the fact that Titan's orbit is eccentric, which (as Lunine says in that "American Scientist" article) would seem to mean that its liquids must be in a subsurface aquifer that greatly reduces their ability to flow from one place to another in response to tides, since their free tidal flow on the surface would otherwise generate enough friction to have long since circularized Titan's orbit. But that conclusion has always been based on the belief that there is nothing else actively working to maintain the initial eccentricity of Titan's orbit -- and we now know that there is some force that does so, since that force must be providing the continuing influx of energy that drives Titan's continuing intense cryovolcanism. (The best theory I've seen is that the driving force is resonant tugs from Jupiter during its periodic movements past Saturn, because these are roughly synchronized with the periods of Titan's orbit around Saturn.)

So: I'm going to have to retract much of what I've been saying. So far, I've provided an explanation for why all of Titan COULD easily be the way the sample of it that we've seen so far appears to be: that is, almost devoid of surface liquid. But it remains entirely possible that there are fairly large bodies of surface liquid on some of the parts of Titan that we have not yet clearly viewed in any way.