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

temperature - Why has Earth's core not become solid? - Physics Stack Exchange

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

Is Earth's core lopsided? Strange goings-on in our planet's interior

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Ancient crystals suggest Earth's core is 4 billion years younger than the planet

Earth has an 'innermost inner core', study says

Scientists discover 'dancing' iron atoms in Earth's core

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?