Apollo Lunar Rock Analysis Reveals Moon's Age as 40 Million Years Older Than Previously Believed

Researchers Used Atom Probe Tomography to Date Lunar Zircon Crystals Collected By Apollo 17 Astronauts in 1972, Anchoring Chronology of the Lunar Magma Ocean Formation

The moon is 4.46 billion years old, approximately 40 million years older than previously believed, according to analysis of lunar rocks collected by Apollo 17 astronauts in 1972.
Researchers used atom probe tomography to date lunar zircon crystals, which are the oldest known solids formed after a giant impact event led to the creation of the moon.
Zircon crystals could not form and survive until after the lunar magma ocean cooled, so their age provides a minimum bound for the age of the moon.
The process of atom probe tomography involves sharpening a lunar sample to a very fine point, then using UV lasers to evaporate atoms from the surface of the tip. The atoms are then analyzed for their weight and composition to determine their age.
The age of the moon is significant to our understanding of Earth's history and its stabilizing effects on our planetary system, including the 24-hour day length and the presence of tides.