Hub brings up an interesting point in his models: the earth splits up. The effect of tidal forces on the planet could indeed cause such a breakup it seems.

However, it also depends on how active the earth is at the time. If the earth is still pliable, it is much more likely to change shape, i.e. to an oblate spheroid, than crack.

Seems to lend some credibility that an earth impact somewhere way back in the past created the moon.

I'd love to see some real core samples from the moon.