May 14, 2023
For millennia, mankind has taken comfort from Earth's steadfast companion - the moon - travelling through space with our home planet on an continuous journey around the sun. But once upon a time, roughly 4.5 billion years ago, the moon wasn't there. And despite it being Earth's cosmic neighbour, scientists still aren't certain how it got there - but NASA has a new theory.
Since the 1980s, the leading theory has been that a massive planet crashed into Earth billions of years ago, ejecting an enormous quantity of gas, magma, and metals that forged the moon over hundreds of years.
However, a study published in The Astrophysical Journal Letters suggests a bold new idea: The moon could have formed in one swift exchange, with a large chunk of baby Earth and its impactor's material blown into a wide orbit - in a matter of hours, not decades or centuries.
If true, the research, which relies on hundreds of extremely high-resolution computer simulations of such a collision, could help resolve a longstanding head-scratcher for scientists about why the lunar crust seems remarkably similar to Earth. It also provides potential answers to why the moon is tilted and has a thin outer layer. Cosmologists yearn to piece together what happened not only to flesh out the moon's origin story, but explain a defining moment in Earth's evolution.
NASA and collaborators put together a quick two-minute animation that attempts to show how the new model would unfold. Here it is...
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