Scientists may have solved another mystery of the Moon. New studies have found evidence that the Moon’s inner core is solid like Earth’s.
Researchers at the University of the Côte d’Azur and the Institute of Celestial Mechanics and Ephemeris Calculations in France have developed models of the interior of the Moon, hoping to discover the inner geological structure of our moon. They determined that, in addition to being solid like Earth’s, the Moon’s inner core is composed of a metal with a density close to iron. They also found that the diameter of the core is about 500 kilometers, or about 15% of the Moon’s total width. Arthur Briaud and his colleagues published their work this week in the journal Nature.
The new analysis also found evidence that the Moon’s mantle is inverted, or essentially moving material from the Moon’s mantle before that layer cools and turns into a solid mass. Scientists suggest this mantle rotation could explain why there is iron on the Moon’s surface. As warmer materials rose to the surface with the rotation of the mantle, volcanic activity on the Moon deposited iron on the surface, and these deposits then cooled and turned into soil.
The new study helps confirm and improve this pre-existing knowledge, even though we know a lot about the Moon’s structure and history. NASA proposed in 2011 that the Moon has an iron-rich, solid core, as well as a liquid outer core. At the time, researchers had used seismic data taken during the Apollo missions to paint a picture of what the Moon’s inner layers looked like. The previous study estimated the inner core to have a diameter of about 482 kilometers, which is pretty close to those of the new research team.
The research team built models of the Moon’s interior structure based on pre-existing datasets such as those collected by NASA. By matching physical observations of the Moon’s gravitational fields, such as those collected in NASA’s GRAIL mission, Briaud and colleagues developed a simulation of the Moon’s interior geology that best fits these built-in data points. The best match included the solid inner core the team described. The process of reaching the conclusion that the Moon’s mantle is inverted was carried out in a similar study. Based on thermodynamic data, the team created a digital model of the Moon’s mantle and studied scenarios where the Moon’s inner layers, made of iron-rich material best match the Moon’s current state, rotate.
Of course, this study isn’t the only recent study to explore the strange geology of the Moon. In a study published in March, researchers in China showed evidence that an enormous water reservoir made of glass beads is located on the lunar surface. Chang’e-5 lunar lander mission scientists have suggested that tiny glass beads found in the Moon’s regolith were caused by asteroid impacts and could store water from the solar wind.
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