Paris · GeoNFC
You stand still. The Earth does not.
A pendulum that changed how people saw an apparently motionless world.
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The place’s story · free
Panthéon
The Panthéon brings together the memory of remarkable people and a famous physics experiment. Foucault’s pendulum makes the Earth’s rotation visible.
- 1851
- Foucault’s experiment under the dome
- 67 m
- historic suspension length
Read the full guide
Stillness can be deceptive. Even while you stand here, you rotate with the Earth. In 1851 Léon Foucault demonstrated that motion with a pendulum suspended beneath the dome of the Panthéon. The historic experiment used a sixty-seven-metre suspension and a heavy metal sphere. The plane of the swing approximately maintains its direction while the Earth rotates beneath it. Relative to the floor, the direction of the swing gradually changes. You can understand the principle without entering: picture a line above a slowly turning plate. The line stays while the plate moves below. This place also has a connection with the Eiffel Tower. In 1898 a radio link connected the two monuments, giving the exploration of the world another invisible route.
Historical source ↗3D · Panthéon
Explore the place in 3D
Stylised model with simplified proportions. Historical Les Halles and the Bastille are illustrative reconstructions.
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This code belongs to this passport. Use it at another stop to unlock both stories.
A stamp records a page visit; it does not by itself verify physical presence.
Atlas of Lost Voices
An address in numbers
The voices of the people who gave the city life are fading. Find their messages and restore the atlas. Five Paris stops form the main quest; Versailles is a bonus.