How the Moon Affects Behavior and Health

Credit: ESO Supernova

4. The Moon’s Structure

The Moon is unique in that its core, crust, and mantle are geochemically different. Its inner core is solid, iron-rich, and has a radius of about 150 miles. The Moon’s outer core is made of liquid iron and has a radius of 190 miles. The area around the core is partially molten and has a radius of roughly 310 miles.

The cause of this structure is a result of the lunar magma ocean that occurred on the Moon’s surface right after it was created. Samples taken from the Moon show that the surface is mostly made from the igneous rock anorthosite. After Jupiter’s Moon Io, the Moon is the second-densest satellite in the Solar System. Its composition is mainly made up of metallic iron mixed with small traces of nickel and sulfur.