Old outer-planet theories, Great ideas that didn't pan out Options

[algorimancer]

...
Back when every asteroid and every outer planet satellite was, as far as we knew, a smooth gray sphere lacking any physical properties besides radius, mass, and orbital elements, I'll be damned if Asimov couldn't find something interesting about them to write about.

I agree. Frankly I mostly found his fiction a bit dull - he bragged about turning-out ridiculously high volumes of work without editing, and it showed; I just don't think he put a lot of effort into developing a plot. On the other hand, I found his non-fiction vastly entertaining, and I learned a great deal from it. Clearly he knew a lot about a lot, and when he wrote what he knew, it was very good indeed. On the other hand, I haven't tried to read any of his fiction in over twenty years, and my tastes today are very different, so perhaps I should give his work another chance.

[J.J.]

Don't know if anyone can qualify this as an "old idea", but something that I always thought was kind of evocative was perhaps first illustrated in the first edition of Hartmann and Miller's The Grand Tour, in which the interface between Jupiter's atmosphere and postulated liquid hydrogen mantle was literally shown as an ocean surface, lit by lightning. I'm pretty sure general opinion has settled on a gradual transition from gas to liquid, but it was still a cool picture.

[nprev]

I still wonder how gradual that transition really is. Phase changes of material are usually fairly abrupt, so you'd think there'd be a boundary/interface region of some sort...an ocean surface still seems plausible to me.

Another point to ponder is that (IIRC) there are at least three radio-emitting regions on the "surface" of the planet with locations stable enough that they've been used to measure the rotation period. What these are exactly is a mystery indeed...some sort of vulcanism, presumably, but the processes involved must be extremely alien to our perceptions. Heck, you can't really use any geological terms with a straight face when thinking in terms of metallic hydrogen, etc...

[EDIT] To Algorimancer: Yes, Asimov's fiction is worth another try. He can be dull, but I've really enjoyed his stuff when re-reading it as an adult...the fine nuances of his work are much clearer now.

[edstrick]

"...are at least three radio-emitting regions on the "surface" of the planet with locations stable enough ..."

These are not on any "surface", other than some magnetic field/plasmasphere interaction "surface" These apparently reflect some of the dynamo-created non-dipole irregularities in Jupiter's magnetic field interacting with the plasma environment of hte planet. These will change with time, but at an arm-waving physical scaling <dimensions and volume> guess, I'd suspect major changes in Jupiter's internal field will take place on time scales of thousands to tens of thousands of years instead of hundreds to thousands, as on Earth.

[dvandorn]

Actually, if you do the "which of these things is more like another" game, you'd have to say that Jupiter's internal arrangements are closer to the Sun's than to Earth's, and the Sun's internal field dynamics change on the order of tens of years. It would also be easy for me to believe that Jupiter's insides are more dynamic and faster-moving than the Earth's, being made of far less dense gas and plasma than the molten and solid rock, nickel and iron that makes up most of the Earth.

Besides, I have this gut feeling that magnetic fields are derived from the spinning of a transition shell around a planet's (or sun's) core, not by the spinning of the core itself. As entropy progresses and a body slowly cools, the nature of that transition shell both fluctuates in well-developed periods and undergoes basic changes with time, so the periodicities and their characteristics change (slowly) as time goes on.

-the other Doug

[nprev]

Yeah, that's why I placed "surface" in BIG quotes (should've boldfaced them); conventional points of reference just don't apply here...