In 1851, when French physicist Léon Foucault performed his pendulum experiment in Paris, he became the first to prove what many scientists of his day already suspected—that the Earth spins on an axis. He conducted his first experiments 170 years ago, in early January 1851, with a relatively small prototype in the cellar of his home. Just a month later, Foucault performed his most famous pendulum demonstration, using a 62-pound spherical weight attached to a 220-foot wire, which was hung from the dome of the Panthéon, a Parisian monument. As the pendulum swung back and forth in a fixed plane, the pointed end of the weight traced lines in a compass-like circle of sand below it. As time passed, the angle of these lines began to change, demonstrating to onlookers that the Earth itself was rotating underneath the pendulum, and by extension, everyone watching was rotating as well, spinning on the surface of the great blue marble around its axis.
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Today in History
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A national icon
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A night of art and culture
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World Migratory Bird Day
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Maritime forest in Cumberland Island National Seashore, Georgia
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Black History Month
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Memorial Day
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Dancing waters of Dubai
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Bridge of Sighs in Venice, Italy
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Sibiu Christmas market, Romania
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Armbrug bridge, Amsterdam, Netherlands
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Papa was a flightless bird
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Celebrating Native American Heritage Day
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Observing World Braille Day in Bavaria
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A big place to shop small
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Women s History Month
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Negratín Reservoir, Granada, Spain
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World Numbat Day
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The snows of Fuji
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Jane’s Carousel delights
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Star Wars Day
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Of moose and Maine
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World Childrens Day
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National Park Week: Wind Cave National Park
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Chinese New Year
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Guilin and Lijiang River National Park, China
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World Space Week
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Grasmere, Lake District, Cumbria, England
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A bridge that rocks
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Celebrating Native American Heritage Month
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Replica of a Viking home in Dublin National Botanic Gardens, Ireland
Bing Wallpaper Gallery

