Did you know? You can watch the Earth rotate thanks to Foucault's pendulum in Paris.

Published by Graziella de Sortiraparis · Photos by My de Sortiraparis · Published on October 2nd, 2023 at 02:28 p.m.
Want to see the Earth spinning at the end of a wire? You're in luck, because two of Foucault's pendulums can be seen in Paris, in the heart of the Panthéon and the Musée des Arts et Métiers.

Fancy a little physics lesson with an easy-to-observe demonstration? The Foucault pendulum lets youwitness in real timethe rotation of the Earth, as demonstrated by a gyroscope, a device rotating around an axis in a constant direction. How does it work? If, as the hours go by, a pendulum's oscillation deviates from its trajectory, it's the point of attachment that's moving, not the object, or even the monument - so it must be the Earth! Invented by French physicist Léon Foucault, this revolutionary device was born in the 19th century, with the very first public demonstration taking place in Paris in 1851.

We can now enjoy this incredible proof of our planet's movement at two Parisian venues. The first is the Panthéon! A superb mausoleum on Mont Sainte-Geneviève, it houses hundreds of tombs of illustrious figures who have shaped France, as well as Foucault's first pendulum, courtesy of Louis Napoléon Bonaparte! Clinging to its vault, the pendulum swings constantly, but we almost missed out on this experience, as it was halted by the coup d'état of 1851! Fortunately, fifty years later, the founder of the Société Astronomique de France put the pendulum back in place, in 1995.

To carry out the experiment, a 67-meter-long steel wire is combined with a 28-kilo brass and lead sphere. The result is such a visual feat that it is reproduced in many places and countries around the world, including Germany, Canada and Japan. The second in the capital is at the Musée des Arts et Métiers, but the pendulum fell over in an accident in 2010. Today, the dented sphere is displayed in a showcase and a copy is installed in its place, still hanging from the vault of the former church of Saint-Martin-des-Champs.

Practical information


Place du Panthéon
75005 Paris 5

Metro: Luxembourg / Cardinal Lemoine / Maubert Mutualité

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