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Scientists Finally Confirm What's Inside the Moon

Accepted submission by hubie at 2023-05-19 03:16:07
Science

The Moon is not made of green cheese after all [sciencealert.com]:

A thorough investigation has found that the inner core of the Moon is, in fact, a solid ball with a density similar to that of iron. This, researchers hope, will help settle a long debate about whether the Moon's inner heart is solid or molten, and lead to a more accurate understanding of the Moon's history – and, by extension, that of the Solar System.

"Our results," writes a team led by astronomer Arthur Briaud [nature.com] of the French National Centre for Scientific Research in France, "question the evolution of the Moon magnetic field thanks to its demonstration of the existence of the inner core and support a global mantle overturn scenario that brings substantial insights on the timeline of the lunar bombardment in the first billion years of the Solar System."

[...] To figure it out once and for all, Briaud and his colleagues collected data from space missions and lunar laser ranging experiments to compile a profile of various lunar characteristics. These include the degree of its deformation by its gravitational interaction with Earth, the variation in its distance from Earth, and its density.

[...] And they found that the lunar core is very similar to that of Earth – with an outer fluid layer and a solid inner core. According to their modeling, 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 entire radius of the Moon.

The inner core, the team found, also has a density of about 7,822 kilograms per cubic meter. That's very close to the density of iron.

[..] We know not long after it formed, the Moon had a powerful magnetic field, which started to decline about 3.2 billion years ago. Such a magnetic field is generated by motion and convection in the core, so what the lunar core is made of is deeply relevant to how and why the magnetic field disappeared.

Journal Reference:
Briaud, A., Ganino, C., Fienga, A. et al. The lunar solid inner core and the mantle overturn. Nature (2023). https://doi.org/10.1038/s41586-023-05935-7 [doi.org]


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