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
More Desktop Wallpapers:
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Let the games (finally) begin!
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Native American Heritage Month
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Once upon a time there was a bridge…
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Into the woods
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Wat Sri Sawai in Sukhothai Historical Park, Thailand
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Heceta Head Light, Florence, Oregon
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Honoring those who served
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Women s History Month
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Jane’s Carousel delights
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Desert rose of Qatar
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Fibonacci Day
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What happened to these clouds?
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Cherry blossom season in Tokyo
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The largest American bison around
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Ponta Delgada
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In the Most Serene Republic
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Bodie State Historic Park, California
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International Tiger Day
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Wild and beautiful Alaska
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The moai you know
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Mosque-Cathedral of Córdoba, Andalusia, Spain
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Sibiu Christmas market, Romania
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Computer Science EDU Week
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April Fools Day
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A century since Tut s tomb was discovered
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Blue paradise on the Costa Brava
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Grizzly bears in Alaska for National Wildlife Day
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Three Natural Bridges, Wulong Karst, China
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The mountain of 30,000 sakura
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Playa del Amor, Marietas Islands, Mexico
Bing Wallpaper Gallery

