Migration? Options

[dvandorn]

I've heard some rumors recently of a new theory of Jupiter's relative position in the solar system -- something about its having formed well outside of the orbit of Saturn and having migrated in to its current position.

First, I guess I'd like to know what, if anything, y'all have heard about this theory. And are there any hard facts supporting it (such as analysis of isotopic abundances, etc.)?

I have to admit, the Saturn system shows a lot of effects of high gravity gradients occurring at some time in the past. What makes me wonder about Jupiter's pasage being responsible is that we don't see the same effects on the Jovian moons that we see on Saturn's.

I guess the question is, how would a Jovian passage so obviously disrupt the Saturn system (tearing moons apart, flinging some completely out of its orbit, placing others in far different orbits than they started in), while the four major moons of Jupiter show no such effects?

-the other Doug