Scientists confirm what is inside the moon: ScienceAlert

Well, the verdict is in. The moon is not made of… Green cheese After all.

A comprehensive study published in May 2023 concluded that the Moon’s inner core is a solid sphere with a density similar to that of iron. Researchers hope this will help settle a long-standing debate about whether the Moon’s inner core is a solid sphere. solid or fusibleand leads to a more accurate understanding of the history of the Moon – and therefore, the history of the solar system.

Our results A team led by astronomer Arthur Briaud wrote: A study by the French National Research Center in France indicates that “the evolution of the Moon’s magnetic field thanks to its evidence of the presence of an inner core and support for the scenario of a global mantle reversal provides fundamental insights into the timeline of lunar bombardment in the first billion years of the Solar System’s life.”

Exploring the interior structure of bodies in the solar system is most effectively done through seismic data. The way sound waves from earthquakes move through and reflect off the material inside a planet or moon can help scientists create a detailed map of the body’s interior.

We have lunar seismic data collected by the Apollo mission, but their resolution is too low to accurately determine the state of the inner core. We know that there is a liquid outer core.But what that includes is still up for debate. Models depicting a solid inner core and a fully liquid core work equally well with the Apollo data.

To figure this out once and for all, Brioud and his colleagues gathered data from space missions and Laser rangefinder Experiments were conducted to compile a profile of various lunar properties. These include the degree of deformation due to its gravitational interaction with Earth, the difference in distance between it and Earth, and its density.

They then ran modeling runs using different base types to find the type that best matched the observational data.

They came up with several interesting results. First, models that closely resemble what we know about the Moon describe active inversion deep within the Moon’s mantle. This means that denser material inside the Moon falls toward the center, and less dense material rises upward. This activity has long been proposed as a way to explain the Moon’s rotation on its axis. The presence of certain elements In the volcanic regions of the Moon. The team’s research adds another point to the supporting evidence.

They found that the Moon’s core is very similar to Earth’s, with a liquid outer layer and a solid inner core. According to their model, the outer core has a radius of about 362 kilometers (225 miles), and the inner core has a radius of about 258 kilometers (160 miles). That’s about 15 percent of the Moon’s total radius.

The team found that the density of the inner core is about 7,822 kilograms per cubic meter. This is very close to the density of the inner core. Iron density.

Curiously, in 2011 a team led by NASA planetary scientist Renee Weber came to a similar conclusion using what were then state-of-the-art seismic techniques on Apollo data to study the moon’s core. They found evidence. It has a solid inner core with a radius of about 240 kilometers and a density of about 8,000 kilograms per cubic meter.

Brioud and his team say their results confirm those earlier findings and make a fairly strong case for an Earth-like lunar core. That has some interesting implications for the evolution of the Moon.

We know that shortly after the Moon formed, it had a strong magnetic field, which began to decline about 3.2 billion years ago. Such a magnetic field is generated by motion and convection in the core, so what the Moon’s core is made of has a lot to do with how and why the magnetic field disappeared.

Given humanity’s hope to return to the Moon in a relatively short time, we may not have to wait long to verify these results with seismic surveys.

The research was published in nature.

A version of this article was first published in May 2023.