Cool Moon Facts by Whip

Real astronomy, with sources. Folklore & tradition.

Fact #057 Geology

The Moon has a core, and part of it is still molten. It is tiny: about a fifth of the Moon's radius, against half for Earth's.

Reanalysis of Apollo seismic data in 2011 found a solid inner core and a fluid outer one, with a partly melted boundary layer above. That small core is a big reason the Moon's dynamo shut down: not enough churning metal to keep a magnetic field running.

Source: Apollo seismic reanalysis, NASA (opens in a new tab) · checked Aug 2026

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