Earth's solid iron core formed a BILLION years ago and is still growing

How has Earth's core stayed as hot as the sun's surface for billions of years?

The core of our planet is about a billion years old, young in cosmic terms!

EarthSky Earth's lopsided core? Strangeness in our planet's interior

How Earth's cooling molten core could destroy the planet - BBC Science Focus Magazine

Earth - Core, Mantle, Crust

Curious Kids: what would happen if the Earth's core went cold?

Why does the Earth have Layers?

How has the inside of the Earth stayed as hot as the Sun's surface for billions of years?

Asal Usul Bahan Tambang di Muka Bumi, by HMT-ITB