Léon Foucault
French physicist (1819-1868) · France · Scientists · Died at 48
Léon Foucault is read about 244 times a day, in 70 languages.
A typical day, 30 days to 22 October 2026
The middle day of the days counted, so one week of news cannot move it. The line under it is the last 397 days, one point a day.
Something wrong?He hung a heavy pendulum from a cathedral dome and let it swing for hours. As it traced a slow circle in the sand, the crowd could finally see what had always been invisible: the Earth turning beneath their feet.
A life in dates
Photos 8
Foucault portre crop
ARAGO Francois Astronomie Populaire T2 djvu 0201 Fig163
Blood corpuscles of a frog. Photomicrograph by Léon Wellcome L0015258.jpg?width=1200)
El mundo físico, 1882 "Experimento de Leon Foucault sobre el calor desarrolado por el magnetismo de rotación". (4074916408).jpg?width=1200)
El mundo físico, 1882 "Heliostato de Leon Foucault". (4052594844)%22._(4052598780).jpg?width=1200)
El mundo físico, 1882 "Telescopio de espejo plateado de Leon Foucault (sistema newtoniano)". (4052598780)
Fizeau Foucault-First Photo of Sun 1845
Foucault 01In their own words 4
, You are invited to come to see the Earth turn, tomorrow, from three to five, at Meridian Hall of the Paris Observatory.
Above all, we must be accurate, and it is an obligation which we intend to fulfill scrupulously.
The phenomenon develops calmly, but it is invisible, unstoppable. One feels, one sees it born and grow steadily; and it is not in one's power to either hasten it or slow it down.
Awards
About this person
Jean Bernard Léon Foucault was born in Paris on 18 September 1819 and trained as a physicist at a time when the planet's rotation was still a matter of abstract theory. In 1851 he suspended his pendulum - first in his cellar, then publicly under the Panthéon's dome - and gave the world its first direct proof that the ground was moving. He went on to measure the speed of light with unprecedented accuracy, discovered eddy currents in conductors, and coined the term "gyroscope" for the spinning instrument that would later steer ships and spacecraft. He died in Paris on 11 February 1868, forty-eight years old, leaving behind the rare gift of making rotation - something everyone experiences but no one sees - suddenly, unmistakably visible.
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