From: Henry Baker <hbaker1@pipeline.com>
Wouldn't tidal forces eventually get rid of the tilt?
From: Joshua Zucker <joshua.zucker@gmail.com>
Tidal forces don't get rid of the tilt, they cause precession.
From: Henry Baker <hbaker1@pipeline.com>
So perhaps it might take longer, perhaps much, much longer, for a tilt to dissipate? Maybe this sort of tidal effect falls off exponentially with distance, so bodies far enough away are "protected"?
If by "exponentially" you mean "a lot"!-) The effect must fall off with a power of the distance. Power is force times speed the force is pushing through, in this case the rate of spin times both masses times the planet's radius. Tidal force must be like the difference between gravity on the two sides of the planet 1/d^2 - 1/(d+r)^2 2dr + r^2 ----------------------- d^4 + 2(d^2 r) + d^2 r^2 About r/d^3. Physics to me seems like having spears of units thrown at you from all directions and dodging them so they cancel. I think both the radius and mass of the satellite cancel when you want to know the half-life of the spin rate. Sun Earth Moon mass 2e30 kg 6e24 kg 8e22 kg distance 1.5e8 km 4e5 km radius 6e3 km 2e3 km The distance from the parent is 375 times as much, and the mass of the parent is 3e5 times as much, so 375^3 / 3e5 ~= 176 times as long to slow down............? --Steve