I often wondered how the core of our planet could spin and NOT the exterior with it?
It not like magma and dirt create a friction-less surface to slide across
How much does the core move per day compared to the 24 hour rotation of the surface?
Its one of those things that always irked me some how...
Just a fraction of a second faster than the outer crust.
Although, there is an alternate theory that the core spins in the opposite direction
Though I would question that on the basis of hydrodyamic flow and tidal eddies that would seem to want to cancel out that opposite spin.