Scientists Dismiss Myth of Moon Made of Cheese

In a groundbreaking revelation, scientists have officially dismissed the long-standing myth that the Moon is made of green cheese! A comprehensive study released in May 2023 has confirmed that the Moon's inner core is a solid mass with a density comparable to iron, shedding light on an ongoing debate about its internal structure and taking us a step closer to understanding the Moon's complex history—and the broader narrative of our Solar System.

Research Led by Arthur Briaud

Led by astronomer Arthur Briaud from the French National Centre for Scientific Research, the research team presents findings that challenge our theories about the Moon's magnetic field evolution. Their work provides compelling evidence for the existence of a solid inner core and proposes a scenario of significant mantle overturning, which could redefine our timeline regarding the Moon's violent bombardment during the first billion years of the Solar System's formation.

Seismic Data and Moon's Interior

Earth scientists have long relied on seismic data to probe planetary interiors, including the Moon. By studying the way seismic waves—created by quakes—travel and reflect, researchers can create detailed internal maps. However, the lunar seismic data from the Apollo missions has been criticized for its low resolution, preventing a conclusive understanding of whether the inner core is solid or molten. While we know there exists a fluid outer core, the exact nature of the Moon's interior has been a topic of debate.

Active Mantle Overturning

In their quest for clarity, Briaud and his colleagues utilized data collected from various space missions and lunar laser-ranging experiments. They examined characteristics like the Moon's gravitational interaction with Earth, fluctuations in distance, and density. By matching observational data with models of various core compositions, they arrived at fascinating conclusions.

The researchers discovered that the Moon is undergoing active overturn within its mantle. This phenomenon occurs as denser materials descend toward the center while less dense materials rise, potentially explaining the composition of different elements found in the Moon's volcanic regions. Their findings add strong evidence to the theory that the Moon's core resembles that of Earth, featuring an outer fluid layer and a solid inner core.

Dimensions and Density of the Inner Core

According to their modeling, the outer core extends about 362 kilometers (225 miles) in radius, while the solid inner core measures approximately 258 kilometers (160 miles)—encompassing about 15% of the Moon's entire radius. The inner core boasts a density of around 7,822 kilograms per cubic meter, closely mirroring that of iron.

Previous Studies and Implications

Remarkably, a previous study in 2011 led by NASA's Renee Weber had highlighted a similar finding using advanced seismological techniques on Apollo data. Weber's team indicated a solid inner core of about 240 kilometers in radius and a density of around 8,000 kilograms per cubic meter. Briaud's findings confirm and build upon this earlier research, presenting a robust argument for an Earth-like lunar core.

This has striking implications for our understanding of the Moon’s evolution. Following its formation, the Moon had a powerful magnetic field that began to wane approximately 3.2 billion years ago. Such a magnetic field is driven by motions and convective currents within the core, making the composition of the lunar core critical for unraveling the reasons behind the disappearance of this magnetic shield.

Future Exploration and Research

With mankind gearing up for a return to the Moon in the near future, the potential for seismic verification of these transformative findings is on the horizon.

Stay tuned for more updates as our understanding of the Moon, and perhaps even the Solar System, continues to evolve! The full research details are now available in the prestigious journal Nature.