Far Side of the Moon May be Colder Than the Near Side, Lunar Rocks Suggest
janrinok writes:
https://phys.org/news/2025-09-side-moon-colder-lunar.html
The interior of the mysterious far side of the moon may be colder than the side constantly facing Earth, suggests a new analysis of rock samples co-led by a UCL (University College London) and Peking University researcher.
The study, published in the journal Nature Geoscience, looked at fragments of rock and soil scooped up by China's Chang'e 6 spacecraft in 2024 from a vast crater on the far side of the moon.
The research team confirmed previous findings that the rock sample was about 2.8 billion years old, and analyzed the chemical make-up of its minerals to estimate that it formed from lava deep within the moon's interior at a temperature of about 1,100 degrees C-about 100 degrees C cooler than existing samples from the near side.
Co-author Professor Yang Li, based at UCL's Department of Earth Sciences and Peking University, said, "The near side and far side of the moon are very different at the surface and potentially in the interior. It is one of the great mysteries of the moon. We call it the two-faced moon. A dramatic difference in temperature between the near and far side of the mantle has long been hypothesized, but our study provides the first evidence using real samples."
Co-author Mr. Xuelin Zhu, a Ph.D. student at Peking University, said, "These findings take us a step closer to understanding the two faces of the moon. They show us that the differences between the near and far side are not only at the surface but go deep into the interior."
The far side has a thicker crust, is more mountainous and cratered, and appears to have been less volcanic, with fewer dark patches of basalt formed from ancient lava.
In their paper, the researchers noted that the far side of the interior may have been cooler due to having fewer heat-producing elements-elements such as uranium, thorium and potassium, which release heat due to radioactive decay.
Previous studies have suggested that this uneven distribution of heat-producing elements might have occurred after a massive asteroid or planetary body smashed into the far side, shaking up the moon's interior and pushing denser materials containing more heat-producing elements across to the near side.
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