Why does the Earth have a magnetic field?

 The Earth's magnetic field is generated by the movement of molten iron and other metals in the Earth's outer core.

This movement creates electric currents, which in turn produce the magnetic field. The process is known as a geodynamo.

The Earth's core is divided into two layers: a solid inner core and a liquid outer core. The outer core is about 2,250 kilometers (1,400 miles) thick and is composed of molten iron and nickel. The movement of this molten metal is caused by heat from the Earth's interior and the decay of radioactive elements.

As the molten metal moves, it creates electric currents through a process called electromagnetic induction.

These currents generate a magnetic field, which is strong enough to extend from the Earth's core to the surface and even into space.