<P> The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids . The Earth's field originates in its core . This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km). It is divided into a solid inner core, with a radius of 1220 km, and a liquid outer core . The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about 6,000 K (5,730 ° C; 10,340 ° F), to the core - mantle boundary, which is about 3,800 K (3,530 ° C; 6,380 ° F). The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core . </P> <P> The mechanism by which the Earth generates a magnetic field is known as a dynamo . The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force). These effects can be combined in a partial differential equation for the magnetic field called the magnetic induction equation: </P> <Dl> <Dd> ∂ B ∂ t = η ∇ 2 B + ∇ × (u × B) (\ displaystyle (\ frac (\ partial \ mathbf (B)) (\ partial t)) = \ eta \ nabla ^ (2) \ mathbf (B) + \ nabla \ times (\ mathbf (u) \ times \ mathbf (B))) </Dd> </Dl> <Dd> ∂ B ∂ t = η ∇ 2 B + ∇ × (u × B) (\ displaystyle (\ frac (\ partial \ mathbf (B)) (\ partial t)) = \ eta \ nabla ^ (2) \ mathbf (B) + \ nabla \ times (\ mathbf (u) \ times \ mathbf (B))) </Dd>

What are the system that effect earth's position and features