Dear Astronomers: […] I've poured through my roughly 200
astronomy books and can't find an answer to this question asked
by a boy at one of my recent talks: Why do the outer gas giant
planets [generally] rotate faster than the inner planets? I was
shocked at first because I realized I should know that! The best
I could come up with was that the planet forming gas/dust around
the bigger planets just happened to have faster moving eddies of
material there than in the inner areas of the forming solar
system. But I'm not sure that's it. Any ideas? What a great
question! Here's my thoughts on the subject, I hope they help:
So the rotation rates of the terrestrial planets, ice-giants and
gas-giant cores are largely determined by the stochastic
collisions near the end of the formation process (when the
colliding bodies are largest and so impart the most angular
momentum). This effect is largely random and so will give a
certain average angular momentum but has not inherent preferred
direction and so won't lead to hu