Crystals brought back by astronauts from the Moon show that our planet’s natural satellite is 40 million years older than scientists thought.
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This was reported by EurekAlert with reference to the results of a study published in the journal Geochemical Perspectives Letters.
More than 4 billion years ago, when the solar system was still young and the Earth was still growing, a giant object the size of Mars crashed into the Earth. The largest piece that broke off from the early Earth formed our Moon. But exactly when this happened remained a mystery, the article says.
In a new study, scientists used zircon crystals brought back from the Moon by astronauts on the Apollo 17 spacecraft in 1972 to pinpoint the timing of the moon’s formation.
Their discovery increases the age of the Moon by 40 million years, to at least 4.46 billion years.
These crystals are the oldest known solids formed after a giant collision. And since we know how old these crystals are, they serve as a reference point for the monthly chronology, the scientists note.
When an object the size of Mars crashed into the Earth and formed the Moon, the energy from the impact melted the rock that later became the surface of the Moon.
When the surface was molten, zircon crystals could not form and survive. So, any crystals on the surface of the Moon must have formed after this ocean of lunar magma cooled, the scientists note. “Otherwise they would have been melted and their chemical signatures would have been erased.”
Since the crystals must have formed after the magma ocean cooled, determining the age of the zircon crystals allowed us to determine the minimum possible age of the Moon. To do this, scientists used an analytical method called atom probe tomography.
In atom probe tomography, we start by sharpening a piece of a lunar sample to a very sharp point using a focused ion beam microscope, almost like a pencil sharpener, the scientists said. “Then we use ultraviolet lasers to volatilize atoms from the surface of this tip. Atoms pass through a mass spectrometer, and how fast they move tells us how heavy they are, which in turn tells us what they’re made of.
Subsequently, this atomic analysis made it possible to determine how many unstable atoms in zircon crystals underwent radioactive decay. For example, radioactive uranium decays over time into lead. Scientists determined how long this process took and, by looking at the ratio of different uranium and lead atoms present in the sample, determined how old it was.
The proportion of lead isotopes found by the researchers indicates that the sample is about 4.46 billion years old. Therefore, the Moon must be at least the same age, the article notes.
According to scientists, the age of the Moon is important to know for a better understanding of the Earth.
The Moon is an important partner in our planetary system – it stabilizes the Earth’s axis of rotation, thanks to it there are 24 hours a day, thanks to which we have ebbs and flows. Without the Moon, life on Earth would look different. It’s part of our natural system that we want to better understand, and our study provides a tiny piece of the puzzle in that big picture, the researchers note.
Source: EurekAlert
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I am David Wyatt, a professional writer and journalist for Buna Times. I specialize in the world section of news coverage, where I bring to light stories and issues that affect us globally. As a graduate of Journalism, I have always had the passion to spread knowledge through writing.