Enough levity! Let's have another go at serious discussion.
I propose starting with the idea that the Earth's core rotates faster than the mantle and crust.
There has been debate about this possibility for around ten years, but it seems to be settled now thanks to modern technology and the analysis of seismic waves over a long period. The verdict is that the inner core rotates faster than the mantle and crust. The latest study has even put a value to this. The inner core rotates at 0.3 to 0.5 degrees per year faster than the mantle and crust. However, it seems that this relative difference must not be taken as a steady rate as it varies over time.
We should now ask the question: “Why this difference?”. There would appear to be at least three candidates for the cause.
1) Mansfield’s idea that when the old moon collided with pre-earth it would have slowed (pre-) Earth’s rotation, and that this slowing would have had more effect on the crust and mantle than on the core.
2) Current geological thinking goes something like this: The heat of Earth's solid inner core churns the molten liquid outer core. The churning generates electric currents and, as a result, creates the planet's magnetic field. Interaction between the electric current and magnetic field is thought to spin the inner core at the same rate that the liquid core just above it is turning, which tends to be slightly faster than the mantle.
3) The moon is not only the major tidal influence on the Earth; it also has a breaking influence on the Earth’s rotation. This influence would be greater on the crust and mantle than it would on the core.
Anyone, any thoughts on a choice of candidate? (With reasons, please.)
