It’s Official: Researchers Finally Verified What Is Inside the Moon

The decision is in, then. After all, the Moon is not composed of green cheese.

According to a detailed analysis released in May 2023, the Moon’s inner core is a solid ball with a density akin to iron. Resolving this long-running controversy – is it solid or molten? – promises to improve our understanding of the Moon’s history and, by extension, the Solar System’s history.

A group led by astronomer Arthur Briaud from the French National Centre for Scientific Research in France contended in a written statement that their discoveries challenged the prevailing understanding of how the Moon’s magnetic field evolves. They explained that their research demonstrated that the existence of an inner core supported a global mantle overturn scenario. This scenario, they claimed, provided valuable new information about the timeline of lunar bombardment during the Solar System’s first billion years.

The Seismic Puzzle: Probing the Moon’s Interior

Seismic data is the most efficient way to probe the inner composition of Solar System objects. Scientists can produce a precise map of a planet or Moon’s interior by observing how seismic waves pass through and reflect off of internal materials.

Yet, we do possess lunar seismic data from the Apollo mission, but its resolution is insufficient to evaluate the state of the inner core confidently. Although the nature of the outer core is still unknown, we know it is fluid. Both fully fluid and solid inner core models perform comparably with Apollo data.

Briaud and his colleagues assembled information from satellite flights and lunar laser range studies to finally create a profile of different lunar features to solve the puzzle. These include the Moon’s density, the change in its distance from Earth, and the degree of deformation caused by its gravitational interaction with Earth.

They then experimented with different core kinds of modeling to see which matched the empirical data the best.

They came to some intriguing conclusions. Our most accurate lunar models depict active overturns occurring deep within the mantle. This implies that less dense stuff climbs upward, and thicker material descends into the Moon’s center. This process has long been proposed to explain the occurrence of specific elements in the Moon’s volcanic areas. Another point is added to the evidence “for” by the team’s research.

Earth’s Echo: Discoveries in Lunar Core Resemblance

They also found that the Moon’s core closely resembles Earth’s core, having a solid center and a surrounding liquid layer. Their simulation indicates that the radius of the inner core is around 258 kilometers (160 miles), and that of the outer core is approximately 362 kilometers (225 miles). That represents almost 15% of the Moon’s total radius.

The scientists also discovered that the inner core’s density is around 7,822 kg/cubic meter, which is highly similar to iron’s.

Interestingly, a group led by NASA Marshall planetary scientist Renee Weber reached a similar conclusion in 2011 while examining the lunar core with Apollo data and cutting-edge seismological tools available at the time. With a radius of over 240 kilometers and a density of almost 8,000 pounds per cubic meter, they discovered evidence of a solid inner core.

Briaud and his colleagues’ findings provide strong evidence for an Earth-like lunar core and validate those earlier findings. Furthermore, this has some intriguing ramifications for the Moon’s evolution.

Implications for Lunar Evolution: Magnetic Mysteries Revealed

We know that the Moon had a strong magnetic field shortly after it originated. That field began to weaken around 3.2 billion years ago. Since motion and convection in the lunar core produce such a magnetic field, understanding the composition of the lunar core is crucial to understanding how and why the magnetic field vanished.

We may not have to wait long for seismic confirmation of these results, considering that humanity hopes to return to the Moon reasonably soon.

Read the original article on: Science Alert

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