Yes, the moon is indeed 40 million years older than we once thought | 24CA News

Roughly 4.5 billion years in the past, our photo voltaic system shaped from a chaotic swirling cloud of fuel, mud and particles. And as our planet shaped, it is believed that one thing roughly the scale of Mars slammed into it. The rocks that remained from that affect got here collectively to kind our moon.

But simply when that occurred has been unsure.

Now, a new examine printed in Geochemical Perspectives Letters that used superior evaluation of crystals from a moon rock collected through the Apollo 17 mission in 1972, has confirmed that the moon shaped roughly 4.46 billion years in the past. That makes it roughly 40 million years older than as soon as believed.

This moon rock — referred to as 72255 — has been analyzed many occasions. In reality, a 2021 examine led by Bidong Zhang and co-authored by Audrey Bouvier — each of whom have been college students at Western University in London, Ont. — was the primary to give you this age. 

However, there was some skepticism on the time.

In order thus far moon rocks, scientists have a look at zircons contained inside them. These crystals — the primary solids to kind after the moon’s magma ocean cooled — are wonderful geological timekeepers, or chronometers, partially as a result of their sturdiness. Additionally, they comprise radioactive uranium, which in flip decays into lead. Scientists know the way lengthy it takes for this to happen.

“But they’re not perfect,” mentioned Philipp Heck of the crystals.

Heck is the curator of meteoritics and polar research on the Field Museum of Natural History in Chicago and senior writer of the brand new examine.

“There can be crystal defects in zircons that can actually occur because of radioactive decay.”

While the 2021 examine used ion microprobe courting, which may see inside roughly 10 microns (one micron is 1/1000 of a millimetre), they wanted to delve even deeper to substantiate that date, all the way down to the nanoscale, or 1000 occasions smaller.

So Heck, lead writer Jenniker Greer and co-authors turned to a technique referred to as atom probe tomography (APT) which may analyze the atoms contained inside the crystal. 

“We take several tiny slivers from that crystal at different locations throughout the crystal, and then we use atom probe tomography to analyze it,” Heck defined. “What it does, basically, is shape the sample into a very sharp tip. And that gets put in a vacuum. A current is applied, and then we hit it with a UV laser, and then … evaporate it atom by atom.” 

They discovered that the lead isotopes left over from the radioactive decay have been roughly 4.46 billion years previous.

“We can now say this grain is really 4.46 billion years old,” Heck mentioned. “This age is now unambiguous.”

Just part of the puzzle

Chris Herd, a planetary geologist and curator of the University of Alberta’s Meteorite Collection Museum, finds the brand new outcomes intriguing. 

“The results, as shown in the paper, they corroborate the original age that they got. So that excites me,” he mentioned. “I’m always interested in that sort of advanced application of methods to samples that were collected, you know, 51 years ago. Because that’s the whole purpose of sample return.”

Herd has a deep curiosity in these kinds of missions. He is a pattern scientist for NASA’s Mars Perseverance rover mission. The rover is busy on the floor of the pink planet analyzing it, but in addition amassing samples as a part of a but undated return mission.

He believes it supplies an impetus to return to the moon.

“That’s a big driver for going back and getting samples from a different part. There’s lots of emphasis on the south pole,” he mentioned. “If you were to go and get something from the surface, you’re gonna get a grab bag of a bunch of different things.’

Meanwhile, Heck said that just because the analysis shows the sample age to be 4.46 billion years old, it doesn’t mean it’s the oldest there is.

“Ours is the oldest instantly dated zircon at present,” he said. “Even with the rocks that we’ve got now from the Apollo program, I’m satisfied there may be older stuff in there. We simply have not discovered that but.”

He said it will be interesting when we collect more moon rocks from other locations, which may provide a fuller picture of the moon’s evolution and history, including more about its magma ocean.

And, he said, learning more about the moon is critical in understanding our own planet.

“We must all the time enhance the chronology as a result of there’s a lot tied to it. It’s anchored within the lunar chronology. It’s additionally anchored within the habitability of Earth,” he said. “The habitability of Earth solely occurred after the moon shaped. And clearly, the moon had a huge impact — no pun supposed — on Earth dynamics.”