Signals from seismic sensors left on the lunar surface by Apollo astronauts in 1971 have revealed that the Moon has a liquid core similar to Earth’s.
Scientists at Nasa applied contemporary seismological techniques to the data being emitted from sensors placed by their colleagues during the U.S. space program’s heyday. The new research suggests the Moon possesses a solid, iron-rich inner core with a radius of nearly 150 miles and a fluid, primarily liquid-iron outer core with a radius of roughly 205 miles.
Where it differs from Earth is a partially molten boundary layer around the core estimated to have a radius of nearly 300 miles. The data sheds light on the evolution of a lunar dynamo – a natural process by which our Moon may have generated and maintained its own strong magnetic field.
The core contains a small percentage of light elements such as sulphur, echoing new seismology research on Earth that suggests the presence of light elements – such as sulphur and oxygen – in a layer around our own core.