Despite being Earth’s closest celestial companion, there have long been doubts about how and when the moon formed.
Now there is evidence that the moon is 40 million years older than scientists previously thought.
The most widely accepted explanation for the Moon’s existence is the “giant impact theory,” which suggests that a Mars-sized planet crashed into Earth.
The debris ejected from the collision is believed to have reassembled and formed the moon.
Now lunar crystals brought back from the last Apollo mission in 1972 have been used to estimate the exact age of the moon.
Despite being Earth’s closest celestial companion, there have long been doubts about how and when the moon formed
Moon crystals brought back from the last Apollo mission in 1972 were used to estimate the exact age of the moon. Pictured: Astronaut Harrison Schmitt collects the sample during the Apollo 17 mission
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The crystals must have formed after the giant impact that created the moon, researchers say, because that high-energy collision melted the rock that eventually became the moon’s surface — and created a magma ocean that would have melted all the crystals as well.
Assuming that the zircon crystals formed later, the scientists used radiometric dating and examined the decay rate of the crystal’s atoms to determine their age.
Their results push the moon’s age by 40 million years to at least 4.46 billion years.
Professor Philipp Heck, lead author of the study from the University of Chicago, explained why it is important to know the age of the Moon, explaining: “The Moon is an important partner in our planetary system – it stabilizes the Earth’s rotation axis, That’s why there are 24 hours in a day, that’s why we have tides.
“Without the moon, life on Earth would look different.”
“It is a part of our natural system that we want to better understand, and our study provides a small piece of the puzzle in this bigger picture.”
More than four billion years ago, when the moon is believed to have formed, our solar system was still young and the Earth was still growing.
To determine the age of the moon, scientists used a sample of lunar dust brought back by Apollo 17 astronauts from the last manned mission to the moon in 1972.
The crystals must have formed after the giant impact that created the moon, researchers say, because that high-energy collision melted the rock that eventually became the moon’s surface — and created a magma ocean that would have melted all the crystals as well
Assuming that the zircon crystals formed later, the scientists used radiometric dating and examined the decay rate of the crystal’s atoms to determine their age
The dust contained tiny crystals that formed billions of years ago.
Professor Heck said: “These crystals are the oldest known solids formed after the giant impact.”
“And because we know how old these crystals are, they serve as anchors for lunar chronology.”
A previous study had hinted at the age of the crystals, but fully understanding them required a look at the nanoscale samples.
Scientists used a method called atom probe tomography, which acts like a “pencil sharpener,” to narrow the lunar sample to a fine point before using ultraviolet lasers to vaporize atoms from that point’s surface.
The atoms moved through a mass spectrometer, their speed indicating how heavy they were and therefore their composition.
An atom-by-atom analysis revealed how many of the atoms inside the zircon crystals underwent radioactive decay, which can convert uranium into lead, for example.
Scientists can tell how old a sample is by looking at the proportion of different uranium and lead atoms, called isotopes.
The proportion of lead isotopes found suggested that the sample was around 4.46 billion years old, so the moon must be at least that old.
Dr. Jennika Greer, lead author of the study published in the journal Geochemical Perspectives Letters, who conducted the study when she was at the University of Chicago but is now at the University of Glasgow, said: “It’s amazing to have evidence.” that the stone you are holding is the oldest part of the moon we have found so far.
“It’s an anchor point for so many questions about the Earth.” “Knowing how old something is helps you better understand what happened to it in its history.”
SCIENTISTS disagree about how the moon formed, but many believe it was the result of a collision between Earth and another planet
Many researchers believe that the moon formed after Earth was hit by a planet the size of Mars billions of years ago.
This is called the giant impact hypothesis.
The theory suggests that the moon is made of debris left over after a collision between our planet and a body about 4.5 billion years ago.
The colliding body is sometimes called Theia, after the mythical Greek Titan who was the mother of Selene, goddess of the moon.
Many researchers believe that the moon formed after Earth was hit by a planet the size of Mars billions of years ago. This is called the giant impact hypothesis
But a mystery remains and is being solved by rocks that the Apollo astronauts brought back from the Moon: Why are the Moon and Earth so similar in composition?
Over the years, various theories have emerged to explain the similar fingerprints of the Earth and the Moon.
The impact may have created a huge cloud of debris that mixed thoroughly with the Earth and later condensed into the moon.
Or Theia could have happened to be chemically similar to early Earth.
A third possibility is that the moon formed from earthen materials rather than Theia, although this would have been a very unusual type of impact.