The moon is the closest celestial body to us in the universe and the only celestial body humans have set foot on, but we’re still learning about it. In fact, Earth’s moon may actually be 40 million years older than scientists previously thought. By analyzing crystals brought back by Apollo astronauts in 1972, atom by atom, a team of geochemists and general scientists determined that this igneous ball is at least 4.46 billion years old. We calculate that there is.The findings are described in a study published today in the journal A letter from a geochemical perspective.
intertwined destinies
Based on samples taken from the moon’s surface, we know that the moon was formed more than 4 billion years ago when a massive object the size of Mars collided with a very young Earth. The largest piece of the planet that shattered during that collision became our moon, which has been intertwined with our solar system ever since.
“Life on Earth is evolving with the moon, and the moon is influencing life on Earth,” says co-author and astrochemist Philip Heck. pop science. “It inspires us and it is reflected in our cultural heritage, but it also has other beneficial effects, such as stabilizing the Earth’s axis of rotation.”
Heck is curator of the meteorite collection at Chicago’s Field Museum and a professor at the University of Chicago. He says studying the moon can also help us understand our own planet through its differences in topography.
“The Earth’s surface is much younger because it is more geologically active. [here] This is due to volcanic activity and weathering,” Heck explains. “The moon’s surface is essentially an archive of the dynamics of the solar system. This is a record we don’t have on Earth, but the evolution of our planet is tied to these collisions that occurred in the early solar system.”
historical perspective
The research team examined lunar dust brought back by the Apollo 17 crew. The 1972 moon landing included NASA geologist Harrison Schmidt, who collected several rocks to study back on Earth. His samples contain very small crystals that are billions of years old and can help show when the moon formed.
When the moon was formed by colliding with the Earth, the energy generated by the impact melted rocks, forming the lunar surface. This provides clues to distinguish between elements that have been present on celestial bodies since their appearance and those that appeared much later. For example, zirconium, a silver metal present on both Earth and the Moon, cannot form or survive on the molten Moon’s surface. The zircon crystals that currently exist on the Moon must have formed after the magma ocean cooled. Determining the age of these structures therefore reveals the minimum possible age of the Moon, assuming they appeared shortly after the impact.
look at each atom
Researchers have previously suggested that the moon is older than estimated, but this new study uses an analytical technique called atom probe tomography to examine the oldest known lunar crystals recovered by humans. This is the first study to accurately determine age.
“Atomic probe tomography begins by honing a section of a lunar sample into a very sharp tip using a focused ion beam microscope,” study co-author and planetary scientist Jennica Greer said in a statement. “It’s like a very high-end pencil sharpener.” . “We then use a UV laser to vaporize the atoms from the surface of the tip. The atoms move through the mass spectrometer, and the speed at which they move tells us how heavy they are, which tells us what they are made of. You can see what is going on.”
This atom-by-atom analysis reveals how many of the zircon crystals have undergone radioactive decay, a process in which atoms in unstable configurations release protons and neutrons. It then transforms into various elements, just as uranium decays into lead. Based on the amount of conversion and the known half-lives of various chemical isotopes, experts can estimate the age of the sample.
“Radiometric dating works like an hourglass,” Heck said in a statement. “In an hourglass, sand flows from one glass bulb to another, showing the passage of time as sand accumulates in the lower bulb. Radiometric dating similarly measures the number of parent atoms and their It works by counting the number of daughter atoms that have been converted. Since we know the conversion rate, we can calculate the passage of time.”
Using samples from Apollo 17, the research team found that the proportion of lead isotopes (daughter atoms produced during decay) indicates that the crystals are about 4.46 billion years old, making it possible to I discovered that it must be at least that old. This brings the moon’s age back 40 million years, but that’s still a very short period of time compared to the approximately 13.7 billion year history of the universe.
“It’s great to have evidence that the stone you have is the oldest piece of the moon ever discovered. It’s an anchor point for so many questions about Earth. “When you know how old something is, you can better understand what happened to it throughout its history,” Greer said.
From Apollo to Artemis
Future research could integrate clues from these decades-old samples with those from samples collected by the upcoming Artemis moon mission. Artemis III is planned for his 2025 year and will land and explore the moon’s south pole. The Apollo 17 mission collected samples from the Taurus-Littrow valley on the eastern edge of Mare Serenitatis, so crystals from other regions of the moon may yield discoveries unimaginable.
[Related: Scientists have new moon rocks for the first time in nearly 50 years]
“I’m sure there’s something older on the moon, we just haven’t found it yet. I even think the Apollo samples contain old zircons. That’s the power of sample return.” says Heck.
The combination of new samples and future technological advances could further solidify how our solar system formed and the subsequent timeline. “Maybe in 50 years, 100 years, or beyond, he will give new generations of scientists access to tools we can only dream of today, to address scientific questions we can’t even think about today.” ,” Heck said. “These templates are a legacy for future generations.”
