Foucault pendulum 2010, the cable suspending the bob in the Musée des Arts et Métiers snapped, causing irreparable damage to the pendulum and to the marble flooring of the museum. An exact copy of the original pendulum has been operating under the dome of the Panthéon, Paris since 1995. At either the North Pole or South Pole, the plane of oscillation of a pendulum remains fixed relative to the distant masses of the universe while Earth rotates underneath it, taking one sidereal day to complete a rotation. So, relative to Earth, the plane of oscillation of a pendulum at the North Pole
Foucault pendulum vector diagrams determines when the Earth's rotation will be observable and only if the "z"-component is not balanced in the same direction on each side. The magnitude of the opposing component is proportional to how long it takes for one full turn of the Earth to be observed in relation to the plane of the pendulum. The length of time is a minimum of one day at the poles, increases from the pole to the equator, and is not visible at the equator (infinitely long). For any two points in the pendulum swing that are equidistant from the center of the swing