The moon is sometimes called ‘two-faced’ because the surface of its side perpetually facing away from Earth looks so different than its side always facing our planet. And the differences run deeper than that, as shown by an analysis of rock and soil retrieved in 2024 by China’s Chang’e-6 robotic lunar spacecraft.
Scientists said the chemical makeup of the minerals in the material obtained from a location on the moon’s far side showed it formed from lava within the lunar mantle about 100km under the surface some 2.8 billion years ago, crystallising at a temperature of about 1,100C. They compared that to data on previously studied samples of rock that crystallised in the nearside mantle.
It turns out that the Chang’e-6 sample, the only one ever gotten from the far side, formed in the lunar interior at a temperature about 100C cooler than the 33 samples previously retrieved from the nearside during Nasa Apollo missions and by a Chinese spacecraft in 2020. The researchers said they believe this difference between the two sides persists to this day.
“Our results demonstrate the existence of thermal asymmetry between the nearside and far side mantle,” said geoscientist Yang Li of University College London and Peking University, who led the study published in the journal Nature Geoscience.
“This takes us one step closer toward understanding the dichotomy of the moon. Specifically, the moon has a dramatic difference for the two sides at its surface, such as volcanism, crust thickness and topography.”
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