Scientists explain why the two sides of the Moon are so different
It appears Earth's gravity is to blame for everything
China's Chang'e-6 mission has delivered rocks from the far side of the Moon to Earth for the first time. A team led by Professor Hejiu Hui of Nanjing University studied them and found evidence that uneven heating from Earth's gravity billions of years ago triggered powerful magma flows inside the satellite.
Researchers compared three types of lunar rocks: anorthosites, magnesium-rich rocks, and basalts from lunar maria. Samples from the far side were similar in composition to rocks from the near side collected by the Apollo and Chang'e-5 missions. This means the Moon's mantle—the layer beneath the crust—is chemically homogeneous on both sides.
However, the Moon's crust is structured differently. Anorthosites from the far side contain more magnesium, while magnesium-rich rocks have fewer rare-earth elements and thorium. This confirms that the crust on the far side is thicker and older, whereas the near side is richer in volcanic plains and KREEP elements (potassium, rare-earth elements, phosphorus).
Scientists proposed a model: after the Moon became tidally locked to Earth, our planet's gravity heated the near side more intensely. This initiated magma circulation: hot flows transported molten rock from the near side to the far side, thickening the crust there. Simultaneously, late magmatic rocks, including KREEP, accumulated on the near side.
The results were published in the journal *National Science Review*. The study explains how Earth's gravitational influence shaped the Moon's asymmetry, preserving a homogeneous mantle but creating contrasting landscapes on the surface.
