Which planet is like the Moon on the outside and the Earth on the inside?

The surface of Mercury is very similar to the surface of the Moon, not only in details, but also in the history of its origin. There are many craters on the surface. The upper layer is a dark lunar-like regolith.
On the other hand, the average density of Mercury (5.43 * 10 ^ 3 kg / m3) is only slightly less than that of the Earth (5.62 * 10 ^ 3 kg / m3). This may indicate an iron core.

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