Earth's outer core
Properties
Estimates for the temperature of the outer core are about 3,000–4,500 K (2,730–4,230 °C; 4,940–7,640 °F) in its outer regions and 4,000–8,000 K (3,730–7,730 °C; 6,740–13,940 °F) near the inner core. Evidence for a fluid outer core includes from seismology which shows that seismic shear-waves are not transmitted through the outer core. Because of its high temperature, modeling work has shown that the outer core is a low-viscosity fluid that convects turbulently. The dynamo theory sees eddy currents in the nickel–iron fluid of the outer core as principal source of the Earth's magnetic field. The average magnetic field strength in the Earth's outer core was estimated to be 2.5 millitesla, 50 times stronger than the magnetic field at the surface. The outer core is not under enough pressure to be solid, so it is liquid even though it has a composition similar to the inner core. Sulfur and oxygen could be present in the outer core.
Earth's outer core-3