Nature · Earth Science
A journey to the centre of the planet
Our planet is layered like an onion, from the thin rocky crust we live on down to a scorching iron core hotter than the surface of the Sun. Each layer — crust, mantle, outer core and inner core — has its own composition, temperature and behaviour, and together they drive everything from earthquakes to Earth’s magnetic field.
As the young Earth melted, its materials separated by density: heavy iron and nickel sank to form the core, while lighter rock floated up to form the mantle and crust. This layering, set over four billion years ago, still shapes the dynamic planet we know today.
From the thin crust through the vast mantle to the molten outer core and solid inner core at the centre.
The thin skin we live on
The crust is a wafer-thin rocky shell — just a few kilometres thick under oceans, tens under continents. It is all we ever see and touch, yet a tiny fraction of the planet.
The slow-flowing bulk of Earth
The mantle makes up most of Earth’s volume — hot rock that flows like thick tar over ages. Its churning convection currents are the engine that drags the plates across the surface.
A sea of molten metal
The outer core is a vast ocean of molten iron and nickel. Its swirling motion acts as a giant dynamo, generating the magnetic field that shields Earth from harmful solar radiation.
A solid iron heart
At the centre lies a solid ball of iron and nickel, as hot as the Sun’s surface yet kept solid by crushing pressure. It slowly grows as the outer core freezes onto it.