apparatus and methods for simulating the earth &# 39 ; s magnetic field . the apparatus includes a spherical structure having a rotational axis and a molten metal therewithin . a support is coupled to the spherical structure so that the spherical structure is rotatable about a rotational axis . rotation of the spherical structure generates inertial forces in the molten metal . the apparatus may include one or more magnetometers operatively coupled to an outer surface of the spherical structure for measuring a magnetic field generated by the spherical structure .