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 the pendulum is swinging or not. If the bob is not allowed to turn with the support-point one twist of the connecting wire will occur in one day at the pole. If the connection apparatus of the pendulum to the bob and to the support were in a fixed relationship (and the connection not allowed to twist, for example, using a rigid rod pinned into place between two sides of the support), then once the plane of the pendulum swing is established in one direction, that plane would be forced to turn with the support and connection. The Earth's rotation