Moon’s explosive birth drove iron deep into Earth's core

Leftovers from the moon’s formation may have tunnelled to the Earth’s core, and make up far more of our planet than we once thought.

According to earlier estimates about 0.5 per cent of our planet’s mass came from swallowing parts of planetesimals, 1000-kilometres across, just after the “Big Splash” that formed the moon. Now, simulations by researchers at the Southwest Research Institute (SWRI) in Boulder and the University of Maryland have upped that percentage to between 1 and 2.5 per cent.

That may not sound like much, but it helps explain something odd about the mantle, the…