Moon Composition & Structure
Quick Facts
The Moon's crust is asymmetrical: thicker on the side farthest from Earth, and thinner on the near side.
The Moon, like Earth, is a layered world with a core, a mantle, and a crust.
What Is the Moon Made Of?
According to leading theories about how the Moon formed, much of the stuff that makes up the Moon was once part of Earth. And like Earth, the Moon consists of three main layers: a crust, a mantle, and a core.
Billions of years ago, the Moon was a molten world. As it solidified, the heaviest materials (metals like iron) sank down into the Moon’s center, and the lighter materials (lower density rocks) rose towards the surface. The result is a structure a bit like a chocolate-dipped cherry – solid core, mostly solid/partly liquid mantle, and thin outer crust.
Earth is an active, lively world. Our planet’s outer core and mantle churn with convection currents, and atop the mantle, tectonic plates diverge and collide. The Moon can seem still and silent in comparison. But the Moon is an active world, too, and its underlying structure is a mystery that scientists are still trying to unravel.