Crust: The moon's surface is dry, dusty and rocky. The rocky crust is about 37 miles (60 km) thick on the side of the moon that faces Earth and about 62 miles (100 km) thick on the opposite side of the Moon. Radioactive dating of moon rocks from NASA's Apollo mission dates the formation of the moon from about 4.3 billion years ago (about 60 million years after the formation of the Earth). Moon rocks that have been analyzed by NASA are similar to Earth rocks, but are richer in the elements aluminum and titanium. When the minerals Armalcolite (named for the three astronauts on NASA's Apollo 11: Neil A. ARMstrong, Buzz ALdrin, and Michael COLlins), Tranquillityite, and Pyroxferroite were found on the moon, they were not known on the Earth. At least some of these minerals have since been found on the Earth.

Rigid lithospheric mantle: This rocky layer is not hot enough to flow. This hard shell is about 620 miles (1,000 km) thick.

Non-rigid mantle: Only the deepest parts of this asthenospheric layer (rock which is less rigid than in a lithosphere but rigid enough to transmit seismic waves) are hot enough to flow.

Core: The non-fluid core may be composed of iron-rich rock. The core contains only about 2-4 percent of the Moon's total mass; this core is probably about 225 miles (360 km) in diameter).