Terrawatch: is Earth’s core going rusty?

Rusty bits on Earth's core could explain how the atmosphere became oxygenated

Whether it is your bike or a garden fork that you forgot to put away, most of us are familiar with the rapid rusting that happens when iron-containing objects are exposed to the elements.

But it isn't just iron left out in the rain that is vulnerable: research suggests Earth's biggest deposit of iron - its core - could also be going rusty.