A bit of Physical Science History

French physicist Léon Foucault publicly demonstrated the Earth's rotation on its axis in 1851 using his famous pendulum, a feat commemorated annually on January 8th (Earth's Rotation Day), providing simple, direct, visual proof of Earth's spin by showing the pendulum's swing plane appear to shift as the planet rotated beneath it.

Key Details of Foucault's Experiment:
@ The Setup (1851): Foucault suspended a heavy pendulum (a brass ball on a long wire) from the ceiling of his home in Paris.
@ The Observation: The pendulum swung back and forth, but over time, its swing plane seemed to rotate relative to the floor.
@ The Conclusion: The pendulum's plane of oscillation remained constant, but the Earth rotated underneath it, proving the planet's rotation.
@ Further Demonstration: He later moved the experiment to the Paris Observatory and then, famously, from the dome of the Panthéon, using a longer pendulum to make the effect more dramatic.

This experiment ...