The Moon, Which Seems Pretty Old, Is Actually Much Younger Than We Thought

·2 min read
Photo credit: Ron Miller
Photo credit: Ron Miller

From Popular Mechanics

  • According to new research, the moon is 85 million years younger than scientists once thought.

  • Computer simulations revealed that the moon formed roughly 4.425 billion years ago.

  • How and when the moon formed has long been a point of contention between planetary scientists.

The moon, it turns out, is much younger than scientists previously thought.

Researchers from the German Aerospace Center and the University of Münster have released new estimates for the age of the moon. According to their modeling, it's 85 million years younger than current estimates suggest.

Scientists have long estimated the moon formed some 4.51 billion years ago when a Mars-sized object (which we've since dubbed Theia) smashed into Earth. At the time, the guts of our newly formed planet were beginning to take shape.

The collision tore away a chunk of Earth's mantle and flung it into orbit, where it morphed into a massive ring of dust and rock that began to clump together. "From this, the moon was formed in a short time, probably in just a few thousand years," planetary scientist and study coauthor Doris Breuer, of the German Aerospace Center, said in a statement.

Breuer and her colleagues revealed in their paper, published in the journal Science Advances, that this infamous impact happened around 4.425 billion years ago, give or take about 25 million years. In the aftermath of the impact, the moon looked a lot like Mustafar—a molten marble with a piping hot magma ocean more than 600 miles deep.

The scientists used computer simulations to show exactly how long it would have taken the moon's magma ocean to solidify, as this would help pinpoint the precise age of the moon. Their models indicated it took a whopping 150 to 200 million years for that magma to fully crystalize. Previous models have suggested it only took 35 million years for the moon's hard, rocky exterior to form.

The impact also kickstarted the formation of Earth's core. Heavier elements like nickel and iron sank toward the planet's center, while a layer of silicate rock formed the mantle layer around it.

"This is the first time that the age of the moon can be directly linked to an event that occurred at the very end of the Earth's formation, namely the formation of the core," planetary scientist Thorsten Kleine, of the University of Münster in Germany, said in the statement.

Over the years, we've able to glean bits and pieces of information from the moon rocks brought back during the Apollo missions and Russia's Luna missions. It's been more than 50 years since we first set foot on the lunar surface, and we still have a lot to learn.

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