Fifty years after Apollo 11 paved the way for the first surveys of the Moon, a team of scientists from CNRS, Université Côte d’Azur, the Côte d’Azur Observatory, and the IMCCE (Paris Observatory – PSL, Sorbonne Université) has shed light on part of its internal structure that had until now remained a mystery: the Moon has a solid core, like the Earth. In addition to this discovery, they also present evidence that explains the presence of iron-rich materials in the lunar crust.
Some twenty years after the identification of a fluid outer core, the team has revealed the existence of a solid inner core about 500 km in diameter, which is about 15% of the total size of the Moon. It is made up of a metal whose density is close to that of iron. Various methods, related in particular to the rotation of the Moon, had already enabled the fluid outer core to be clearly identified. However, the solid core remained undetectable, due to its small size. Its existence has now been demonstrated using INPOP ephemeris and data from various space missions and from lunar laser ranging.
Their work was published in Nature on May 3, 2023.