How do we know the centre of the earth is Iron?

Question

Like how are scientists 100% sure when we’ve never dug that far down

Thanks in advance

In: 23

Answer 1

Earthquakes generate seismic waves that pulse through the entire planet.

When measuring these at different points around the globe, we noticed that the waves don’t travel directly through the center, they reflect off of something dense and solid in the middle.

When we measure Earth’s gravity we get a similar conclusion: Earth is much heavier than a solid ball of rock would be.

When we measure Earth’s magnetic field we get yet another similar conclusion: something large and metallic is sloshing around in the center.

All these observations combine to make it pretty indisputable: there’s a huge metallic core in the center of the planet that deflects waves, generates a magnetic dynamo, and makes the planet extremely dense.

It’s assumed to be mostly iron because dying stars produce iron in huge quantities – it’s by far the most common heavy metal in the universe and has the right properties to generate the density and magnetism measurements we see.