Scientists reveal what is inside the Moon

A team led by astronomer Arthur Briaud from France's National Centre for Scientific Research has raised important questions about the evolution of the Moon's magnetic field and provided valuable insights into the timeline of the lunar bombardment during the first billion years of the Solar System. Their study, which was published in the journal Nature, suggests the presence of an inner core within the Moon— a discovery that could reshape our understanding of its internal structure. Seismic data is one of the most effective ways to examine the internal structure of objects in the Solar System. Acoustic waves generated by earthquakes can pass through and reflect off a planet or a moon, helping scientists create detailed maps of their internal compositions. While seismic data from the Apollo missions is available, its resolution is insufficient to definitively determine the state of the Moon's inner core. Although the existence of a liquid outer core is confirmed, what is underneath the outer core remains debated. The Apollo works equally well with both modals supporting the presence of a solid inner core and a fully liquid core. The team's research shows that models indicating active overturn in the Moon's mantle, where denser materials move toward the center while lighter materials rise, are highly consistent with what is already known about the Moon. Furthermore, the research indicates that the Moon's core bears a strong resemblance to Earth's core, featuring a liquid outer layer and a solid inner core. According to the team's models, the outer core has a radius of approximately 362 kilometers, while the inner core's radius is about 258 kilometers, constituting roughly 15% of the Moon's total radius. The inner core's density was found to be around 7,822 kilograms per cubic meter, which is very close to that of iron. It is known that shortly after its formation, the Moon had a strong magnetic field, which began to weaken around 3.2 billion years ago. This type of magnetic field is generated by movement and convection within the core, making the composition of the Moon's core crucial to understanding how and why its magnetic field has diminished. Given the renewed interest in lunar exploration, these findings could be verified through seismic studies sooner rather than later.