Scientists Have Officially Confirmed the Composition of the Moon’s Interior

A detailed study released in May 2023 revealed that the Moon’s inner core is a solid sphere with a density similar to iron. Researchers believe this discovery will resolve a long-standing debate about whether the Moon’s core is solid or molten, providing a clearer understanding of the Moon’s history and, in turn, the history of the Solar System.

“Our findings,” stated a team led by astronomer Arthur Briaud from the French National Centre for Scientific Research, “challenge existing theories about the Moon’s magnetic field by confirming the presence of its inner core. This supports a global mantle overturn scenario and provides valuable insights into the timeline of lunar bombardment during the Solar System’s first billion years.“

Investigating the interior of celestial bodies is most effectively done using seismic data. The movement and reflection of acoustic waves from quakes as they pass through a planet or moon’s material allow scientists to map its internal structure.

Apollo Seismic Data Inconclusive on Lunar Core Composition

While we have seismic data from the Apollo missions, its resolution is too low to definitively determine the state of the Moon’s inner core. We know the Moon has a fluid outer core, but the details of its composition are still debated. Both models suggesting a solid inner core and an entirely fluid core are consistent with the Apollo data.

To resolve this, Briaud and his team gathered data from space missions and lunar laser-ranging experiments to create a detailed profile of the Moon’s characteristics, including its deformation due to gravitational interactions with Earth, variations in its distance from Earth, and its density.

They then ran models using different core types to determine which one most closely aligned with the observational data.

The team made several intriguing discoveries. First, their models that most closely matched our current understanding of the Moon suggest active overturn within its deep mantle.

This means denser materials sink toward the center, while less dense materials rise. This process has long been considered a potential explanation for the presence of certain elements in the Moon’s volcanic regions, and the team’s findings add further support to this theory.

Lunar Core Structure Mirrors Earth’s, with Fluid Outer Layer and Solid Inner Core

They also found that the lunar core closely resembles Earth’s, with an outer fluid layer and a solid inner core. Their model estimates the outer core’s radius at about 362 kilometers (225 miles), while the inner core has a radius of roughly 258 kilometers (160 miles), which accounts for about 15 percent of the Moon’s total radius.

Additionally, the inner core’s density was found to be around 7,822 kilograms per cubic meter, which is strikingly close to the density of iron.

2011 Seismological Study Reveals Similar Findings on Lunar Core

Interestingly, in 2011, a team led by NASA Marshall planetary scientist Renee Weber reached a similar conclusion using the latest seismological techniques at the time to analyze Apollo data and study the lunar core. They found indications of a solid inner core with a radius of approximately 240 kilometers and a density of around 8,000 kilograms per cubic meter.

According to Briaud and his team, their results confirm the earlier findings and provide strong evidence for an Earth-like lunar core. This has intriguing implications for understanding the Moon’s evolution.

Shortly after its formation, the Moon had a strong magnetic field, which began to weaken around 3.2 billion years ago. Such a magnetic field is generated by motion and convection within the core, so understanding the composition of the lunar core is crucial to explaining how and why the magnetic field disappeared.

With plans for humans to return to the Moon in the near future, seismic confirmation of these findings may be just around the corner.

Read the original article on: Science Alert

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