A Foucault pendulum (named for its inventor, physicist Jean Bernard Léon Foucault) visually demonstrates the Earth’s rotation on its axis. While the pendulum’s arc appears to move slightly clockwise with each swing, it is actually the Earth underneath that is moving. Museum visitors can observe the pendulum knocking over dominoes and other small objects as it makes its circular journey. The Museum’s Foucault pendulum has a 32-foot-long wire and 270-pound bob. Because of the pendulum’s weight, the lobby roof was cut open during installation and a support unit constructed so that the pendulum could be hung from the highest possible point.