January 8 is Earth’s Rotation Day, the day commemorates when French Physicist, Leon Foucault, demonstrated the Earth rotates on its axis in 1851.

To prove his theory, Foucault suspended a lead-filled brass sphere, now called the Foucault Pendulum from the top of the Pantheon in Paris. He showed that the plane of the swing of the pendulum rotated relative to the Earth’s rotation. You can now see the Foucault Pendulum demonstrating the rotation of the Earth in science museums around the world.

Links:
Earth’s Rotation Day: History and significance behind the day that celebrates the 24-hour phenomenon

Megaconstructie veranderde mogelijk de rotatie van de aarde

Earth Rotation Day 2026: 7 Fascinating Facts That Show Why This Day Matters