Earth's magnetic field. Cutaway artwork of the Earth illustrating the convection within its interior and the pattern of its magnetic field. The Earth has a solid centre (inner core, blue), which is surrounded by a liquid layer (the outer core, yellow) where molten iron circulates (red arrows). The outer core is surrounded by the mantle (red). The convective motion of molten iron in the outer core combined with the Earth's rotation is what produces the dipole magnetic field (blue arrows).