Hidden Hills, California
February 20, 2021
You may have read the recent news that 42,000 years ago the Earth’s magnetic poles flipped for 800 years with dramatic effects on the Earth. I (of course) know that Earth has a magnetic field but had never thought what causes it.
Thanks to Google - and sorting through some answers I did not understand- I found this kind of straight-forward explanation:
The Earth's outer core is in a state of turbulent convection as the result of radioactive heating and chemical differentiation (think of this as chemicals breaking apart). This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic energy is converted to electrical and magnetic energy. Basically, the motion of the electrically conducting iron in the presence of the Earth's magnetic field induces electric currents. Those electric currents generate their own magnetic field, and as the result of this internal feedback, the process is self-sustaining so long as there is an energy source sufficient to maintain convection.