Nice, France — A recent investigation has settled a longstanding debate about the Moon’s internal structure, revealing that its inner core is a solid entity, similar to iron in density. This new finding is expected to enhance our understanding of the Moon’s history and its connection to the broader Solar System.
Led by astronomer Arthur Briaud from the French National Centre for Scientific Research, the research provides fresh insights into the evolution of the Moon’s magnetic field. The discovery of a solid inner core challenges previously held beliefs and opens up new discussions regarding the Moon’s geological timeline, particularly the impact of celestial bombardments in its early years.
To obtain this crucial data, the research team utilized seismic information gathered from the Apollo missions, along with data from various space exploration projects and lunar laser-ranging experiments. They aimed to discern whether the Moon’s core was solid or molten. Despite the limitations of earlier Apollo data, which lacked the resolution needed to draw definitive conclusions, the team conducted detailed modeling of the Moon’s characteristics, including its density and gravitational interactions with Earth.
The researchers’ findings indicate that there is significant activity within the Moon’s mantle, characterized by a process called overturn, where denser materials sink and less dense minerals rise. This movement helps explain the presence of distinct elements found in volcanic regions of the Moon and adds weight to the case for a dynamic interior.
Interestingly, the study also posits that the Moon’s core bears a strong resemblance to Earth’s core, comprised of a solid inner section surrounded by a fluid outer layer. The measurements suggest that the lunar core features an outer radius of about 225 miles and an inner radius of roughly 160 miles, constituting about 15% of the Moon’s total radius. The inner core has a density close to 7,822 kilograms per cubic meter, aligning closely with elements seen on Earth.
This new research builds on earlier studies, including a 2011 investigation led by NASA’s Renee Weber, which indicated the presence of a solid inner core. The latest findings reinforce these earlier conclusions and strengthen the argument for a geologically complex lunar core, which has implications for understanding the Moon’s historical magnetic field.
In the early years following its formation, the Moon is believed to have possessed a robust magnetic field, which began to fade approximately 3.2 billion years ago. The characteristics of the inner core are key to understanding why this magnetic field diminished over time.
As interest in lunar exploration continues to grow, particularly with plans for future missions, researchers are hopeful that upcoming seismic studies will validate their findings. This work, which has been published in a leading scientific journal, is set to reshape our understanding of the Moon and its role in the Solar System’s history.