Scientists have uncovered a discovery that would have been inconceivable in 1972, more than 50 years after astronauts returned with the last batch of Apollo-era moon rock.
That year, astronauts Eugene Cernan and Harrison Schmitt, the first scientist-astronauts, became the final humans to set foot on the moon.
Cernan and Schmitt chose the Taurus-Littrow Valley on the outskirts of Mare Serenitatis as a geologically diverse location.
They collected a total of 741 samples of lunar rock and dirt, weighing 110.5 kilograms (243.6 pounds). The samples comprise basalt, breccia, and highland crustal rocks, the three principal lunar rock types.
So, how old is the moon exactly?
According to the latest research, the moon is around 40 million years older than previously thought.
It appears to have formed around 4.46 billion years (or “GA”—giga annum) ago, placing it inside the first 110 million years of our solar system’s inception.
Many lunar samples have been investigated over the years, but a significant amount has been kept and released to researchers gradually, since scientists predicted early on that technology would advance over time and allow for deeper insights.
The findings, which will be published in Geochemical Perspectives Letters on October 23, 2023, are based on a novel method known as atom probe tomography (APT).
“I love the fact that this study was done on a sample that was collected and brought to Earth 51 years ago. At that time, atom probe tomography wasn’t developed yet and scientists wouldn’t have imagined the types of analyses we do today,” Philipp Heck, a senior author of the study, told the Reuters news agency
How did scientists learn about the moon’s new age?
The researchers reanalyzed crystals from lunar sample 72255, which contained 4.2 billion-year-old zircon—some of the oldest ever discovered.
Zircon is also the oldest material known to exist on Earth, according to scientists, and as such, it contains significant information regarding the genesis of our planet and life as we know it.
The current study’s researchers used APT, which has nanoscale spatial resolution, to identify lead clustering in the samples. The lead distribution is frequently used to evaluate the age of zircon in rock.
Why is zircon important in determining the age of the moon?
The researchers noted in their paper that the massive impact idea is “the leading hypothesis” for the creation of the Earth-moon system. A massive object called Theia, probably the size of Mars, is thought to have collided with Earth during its formation. According to researchers, this resulted in the ejection of material that swiftly solidified into the sphere we know as our moon.
This resulted in the Lunar Magma Ocean, a theory that, according to the scientists, describes the composition of the moon’s interior.
Subsequent bombardments of the moon’s surface “reworked and melted the earliest crust,” according to the researchers, leaving some zircon changed and other zircon pure or preserved.
