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University of Maryland 30-Ton Metal Sphere Spins
for Magnetic Field Investigation
Videos for Engineers

Get ready to flip the dial on your compass by 180° soon. Well not real soon, but indications point to another reversal of the Earth's magnetic field reversal in as little as 1,500 years. To more accurately investigate the phenomenon, researchers at the U. of MD have constructed a 30-ton sphere that spins at more than 90 mph to generate magnetic fields. The 10-ft sphere is filled with 13.5 tons of liquid sodium to mimic the Earth’s liquid-iron center core. A 3.3-ft sphere counterrotates inside the larger one. Both spheres are driven by 350-hp electric motors. At full speed the outer sphere spins at 240 rpm. The inner sphere reaches 960 rpm.