Globe: Umberto Shtanzman/Shutterstock Illustration: M. Lines of the field converge where magnetic force is strong, at the poles, and spread out where it is weak.
GIANT MAGNET Circulating electric currents in the molten iron outer core give rise to Earth’s magnetic field, which is like a bar magnet tilted 11 degrees from the spin axis of the planet and thus from the geographic poles. The setup allows the team to study how heat and rotation might affect the movement of the iron in Earth’s outer core. The spheres rotate independently at varying velocities. Only these dolls contain 12 tons of molten metal and spin independently at astonishing speeds.ĭYNAMICS OF A DYNAMO To simulate Earth’s dynamo, the space between the inner and outer spheres of the University of Maryland device is filled with liquid sodium. It’s two spheres, actually - nestled one within the other like a pair of Russian dolls. Daniel Lathrop spent seven years and $2 million building the stainless steel sphere in his laboratory.
