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 be determined. The inverse ratio will determine the time observed for one full rotation of the pendulum swing in comparison to the duration at the pole of one day. From the diagrams two points of the pendulum swing can be chosen to project straight down to two points on opposite sides of the Earth (180° apart). This makes it easy to obtain the velocity vector difference and then the time observed for a full rotation from the inverse ratio. The examples show that the Earth turns underneath the plane of the pendulum swing and how this change in relationship can