Moon's far side is volcanic-free due to 'giant impact'
China's Chang'e-6 mission just cracked a big moon mystery: why the far side has barely any volcanoes.
By studying rocks from the South Pole-Aitken Basin, scientists found evidence that a massive collision 4.25 billion years ago deeply affected the Moon's interior and suppressed volcanic activity on its far side.
Potassium clues point to ancient crash
The team noticed these rocks had way more of the heavy potassium-41 isotope than samples from the near side (the one we see).
After ruling out other causes, they realized only a giant impact could explain this weird chemical signature.
How 1 crash changed everything
That ancient smash-up created so much heat and pressure that lighter potassium evaporated away, leaving behind heavier stuff.
This likely suppressed magma generation under the far side, which may help explain why it's so quiet compared to the near side with its big dark plains.
Why it matters
These chemical "fingerprints" help scientists piece together how wild events shaped our moon—and remind us there's still plenty left to discover about our closest neighbor in space.