Katharina Buczek
The moon is currently over 4.5 billion years old, forming after a massive asteroid or planetary body collided with our young Earth and launched pieces of dust and rock into orbit.
While scientists have been able to determine the age of the moon itself, though, figuring out the lunar surface’s age has been particularly tricky– mainly because different measurement methods return conflicting results.
One technique, for instance, involves counting up the number of craters– or impacts– on the moon’s surface. Then, scientists estimate just how long it would take the moon to receive that many hits.
This method is viable since, unlike Earth, the moon does not have plate tectonics or erosion. In other words, the surface stays essentially unchanged, while these impact scars would be erased over millennia on Earth.
However, crater counting does not always match up with dating results that scientists receive after directly studying moon rocks retrieved by crewed Apollo missions to the moon’s surface.
But, researchers from Norway and France recently bridged the gap between these two methods– essentially “resetting the clock” for the moon’s craters and correcting the mistakes between these two dating methods.
The team figured out a way to coordinate the two systems and recalibrate their results by examining lunar surface samples returned by the Apollo, Chang’e, and Luna missions. Afterward, they tallied the number of craters surrounding the sites where the rock samples were originally found to correlate the ages.
Finally, the researchers generalized this data across the entire lunar surface in order to gather better age estimates in regions where scientists have only counted craters– not collected rock samples.
This meticulous process revealed that the larger areas of the moon’s crust are approximately 200 million years older than we previously thought. The remarkable discovery will allow scientists to better understand the sequence of events involved in the moon’s surface evolution.
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