THE MAGNETIC FIELD MYSTERY

The Moon has an external magnetic field – it’s less than one-hundredth that of Earth’s magnetic field. It’s not a dipolar magnetic field like Earth, which has a field that radiates from the north and south poles. Researchers believe the Moon once had a dipole magnetic field, created by a dynamo – a convecting liquid core of molten metal. But we aren’t sure what powered that dynamo. It could have worked like Earth’s dynamo. Earth’s dynamo powers itself as elemental radioactive decay maintains convection in the core.

The Moon could also have had a dynamo powered by the cooling of elements at the core.