wow. You really got into "the land before time" didn't you? Are you worried the Morlocks will surface and abduct our children? or is it the mole men? I don't mean to be disrespectful, but as conspiracy/fringe science goes, even that one is a stretch. You do realize that the magnetic field that protects the planet's atmosphere is due to the stuff in the core don't you? Not to mention that gravity kind of depends on mass.