The core is divided into two regions that exhibit very different mechanical strengths. The outer core is a liquid layer 2,270 kilo- meters (1,410 miles) thick. It is the movement of metallic iron within this zone that generates Earth's magnetic field. The inner core is a sphere with a radius of l 216 kilometers (754 miles) Despite its higher temperature, the iron in the inner core is solid due to the immense pressures that exist in the center of the planet.