Here's why:
* The Outer Core: This layer is composed of liquid iron and nickel. The intense heat and pressure within the outer core create convection currents. These currents, combined with the Earth's rotation, generate electric currents that in turn produce the magnetic field.
* The Inner Core: This is a solid sphere of iron and nickel. While it doesn't directly create the magnetic field, its presence and interaction with the outer core are crucial for maintaining the field's stability.
Think of it like a giant dynamo! The movement of the liquid metal in the outer core acts as the dynamo's spinning armature, generating the magnetic field.
