The Moon is now believed to have formed as early as 50 million years after the solar system took shape 4.56 billion years ago. A detailed analysis of moon rock samples collected by NASA’s Apollo 12 mission in 1969 has yielded incredible new findings about the Moon’s chemical composition. The discovery contradicts earlier estimates the Moon formed 150 million years after the solar system. The findings were published on Monday, July 12, in the journal Nature Geoscience.
Geologists at the University of Cologne’s Institute of Geology and Mineralogy analysed a sample of lunar ilmenite basalt collected by Apollo 12.
The small sample of grey rock was found to contain deposits of glass, left behind when another basalt rock was struck.
The geologists then compared the samples to other moon rocks collected by NASA’s six lunar landings to chart out the history of the Moon.
According to Dr Raúl Fonseca, whose work focuses on the process inside of the Moon, the lunar study focused on the specific chemical signatures of the different types of rock collected by the Apollo missions.
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He said: “By comparing the relative amounts of different elements in rocks that formed at different times, it is possible to learn how each sample is related to the lunar interior and the solidification of the magma ocean.”
At one point in its ancient history, the Moon is believed to have been covered in an ocean of molten rock.
The Moon itself, scientists agree, formed when a Mars-sized object struck our young Earth.
The force of impact launched vast amounts of debris into space which, over time, combined into a giant ball of rock.
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Then, as the Moon’s magma cooled down, various types of rock formed.
According to Dr Maxwell Thiemens, who led the study, analysing the various types of moon rock is key to dating the Moon’s age.
He said: “These rocks recorded information about the formation of the Moon, and can still be found today on the lunar surface.”
And analysing the Moon’s age and chemical composition can be equally important for understanding how our planet formed more than 4.5 billion years ago.
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Dr Peter Sprung, who co-authored the study, said: “Such observations are not possible on Earth anymore, as our planet has been geologically active over time.
“The Moon thus provides a unique opportunity to study planetary evolution.”
To determine the Moon’s age, the scientists analysed the chemical compounds of uranium, hafnium and tungsten in the lunar rock.
The isotope hafnium-182, for instance, decayed into tungsten-182, over the first 70 million years of the solar system.
The rate of radioactive decay data collected from the Apollo samples paired with laboratory experiments narrowed down the Moon’s age to within 50 million years of the solar system’s formation.
Professor Carsten Münker, who took part in the study, said: “This age information means that any giant impact had to occur before that time, which answers a fiercely debated question amongst the scientific community regarding when the Moon formed.”
And Dr Thiemens said: “Mankind’s first steps on another world exactly 50 years ago yielded samples which let us understand the timing and evolution of the Moon.
“As the Moon’s formation was the final major planetary event after Earth’s formation, the age of the Moon provides a minimum age for Earth as well.”