Relive great moments in science on the exact patch of Earth where they took place. Justin Mullins is your guide
Foucault’s pendulum
, Place du Panthéon, Paris
By the mid 19th century, scientists had long known that the Earth rotates. Yet an uncomfortable puzzle remained. Nobody knew how to demonstrate this rotation in a simple and easy way. Then in 1851, French physicist Léon Foucault devised a way, which he demonstrated publicly by hanging a 28-kilogram bob from the dome of the Panthéon, a mausoleum in Paris. As the pendulum swings, the Earth rotates beneath it, making the…
