Earth's rotation Foucault in 1851, which consisted of a lead-filled brass sphere suspended from the top of the Panthéon in Paris. Because of the Earth's rotation under the swinging pendulum, the pendulum's plane of oscillation appears to rotate at a rate depending on latitude. At the latitude of Paris the predicted and observed shift was about clockwise per hour. Foucault pendulums now swing in museums around the world. Earth's rotation period relative to the Sun (solar noon to solar noon) is its "true solar day" or "apparent solar day". It depends on the Earth's orbital motion and is thus affected by changes
Foucault pendulum vector diagrams Earth in relation to the pendulum swing increases in time (decreases in effect) with decreasing latitude is related to the Coriolis Effect. As summarized in the Coriolis effect article, the effect is greatest in polar regions where the surface of the Earth is at right angles to the axis of rotation (the central axis of the pendulum aligns with the Earth's axis of rotation). The Coriolis effect decreases nearer the equator because the surface of the Earth is parallel to the axis of rotation (the central axis of the pendulum is perpendicular with the Earth's axis of rotation). Refer to