We’ll want way more candles on the cake in terms of celebrating the Moon’s subsequent “birthday.” That’s as a result of scientists have decided it’s truly 40 million years older than beforehand thought, a  conclusion relies on an evaluation of historical lunar crystals. 

The Moon’s origin story begins in chaos: a colossal object, as massive as Mars, collided with the nascent Earth. The particles from this violent encounter finally coalesced to kind the Moon. Nonetheless, pinning down the precise timing of this occasion has puzzled scientists for years.

To resolve this puzzle, researchers turned to a lunar time capsule that lies samples of Moon mud, collected through the Apollo 17 mission in 1972. Amongst this mud had been zircon crystals, historical fragments that survived the turbulent occasions following the Moon’s violent formation.

“These crystals are the oldest identified solids that shaped after the giant impact. And since we all know how outdated these crystals are, they function an anchor for the lunar chronology,” says Philipp Heck, the examine’s senior creator from the Subject Museum and the College of Chicago, in a statement. “When the floor was molten like that, zircon crystals couldn’t kind and survive. So any crystals on the Moon’s floor should have shaped after this lunar magma ocean cooled. In any other case, they might have been melted and their chemical signatures can be erased.”

To uncover the crystals’ age, and due to this fact the Moon’s, the researchers employed a complicated method often known as atom probe tomography. Jennika Greer, the examine’s lead creator and a researcher on the College of Glasgow, describes this course of as analyzing the pattern “atom by atom.” This methodology entails sharpening the lunar pattern right into a positive tip, just like a pencil sharpener.

“Then, we use UV lasers to evaporate atoms from the floor of that tip,” she explains. “The atoms journey by way of a mass spectrometer, and how briskly they transfer tells us how heavy they’re, which in flip tells us what they’re product of.”

However how does figuring out atoms point out age? It’s all about radioactive decay – the method the place unstable atoms lose vitality over time. By evaluating the amount of decayed uranium atoms to these of the lead they flip into, scientists can calculate the time elapsed.

“Radiometric relationship works a little bit bit like an hourglass,” Heck analogizes. “In an hourglass, sand flows from one glass bulb to a different, with the passage of time indicated by the buildup of sand within the decrease bulb. Radiometric relationship works equally by counting the variety of mother or father atoms and the variety of daughter atoms they’ve reworked to. The passage of time can then be calculated as a result of the transformation fee is thought.”

This methodology revealed that the zircon crystals are round 4.46 billion years outdated, setting a brand new minimal age for the Moon.

Reflecting on the significance of this discovery, Greer shares her pleasure. “It’s wonderful with the ability to have proof that the rock you’re holding is the oldest little bit of the Moon we’ve discovered to this point. It’s an anchor level for so many questions in regards to the Earth. When you understand how outdated one thing is, you may higher perceive what has occurred to it in its historical past.”

Understanding the Moon’s age isn’t only a matter of cosmic curiosity. As Heck notes, the Moon performs a significant position in Earth’s historical past and present-day life, influencing every part from the size of our day to the existence of tides.

By pushing the boundaries of science with atom probe tomography and the examine of lunar samples, researchers haven’t solely unearthed particulars in regards to the Moon’s previous but additionally opened doorways to deeper questions on our planet and the broader Solar System.

The analysis is revealed within the journal Geochemical Perspectives Letters.