Not being a scientist, I can only guess as to what keeps our Earth’s magnetic field in balance but I suspect it is a number of different factors which include the relationship to the other planets, stars, our own Moon and the inner crust of our own Earth that provides that balance. I also believe that all these things were created by God and are kept in that state of balance by that Supreme Being even as these areas undergo constant changes and fluctuations that occur daily as well as over a long period of time.
Amen!