Although the Moon may seem like a solid rock, it’s actually differentiated like Earth; it has a core, a mantle and a crust. The Moon’s structure likely came from the fractional crystallisation of a magma ocean that once covered it. This probably happened not long after the Moon was formed, about 4.5 billion years ago. As the magma ocean cooled, its composition changed as the different minerals within the melt crystallised into solids. The denser materials sank, forming the mantle, while less dense materials floated on top and formed the crust.
The core is probably very small, with a radius about 20 per cent the total size of the Moon. By contrast, most differentiated celestial bodies have cores about 50 per cent of their total size. The core itself comprises…
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All About Space Annual (Digital) - 1 Issue, All About Space Annual (2024)