The Moon has a core made of iron with small amounts of sulfur and nickel. It’s much smaller relative to its size than Earth’s core. There’s likely a solid inner core and a partially molten outer layer. This was confirmed using seismic data and laser ranging. The core explains weak magnetic remnants. It also hints at early lunar dynamo activity.
This matters because cores drive magnetic fields. Understanding why the Moon’s field faded helps explain planetary magnetism. That includes why Earth stayed protected.
It also refines formation models. Core size supports the giant impact theory. Internal structure tells origin stories.
The Moon’s core is only about 20% of its radius. Earth’s core is more than half.
NASA [nasa.gov]