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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Kjell Henriksen Observatory
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Aw shucks, It s Oyster Day
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A. M. Foster Bridge in Cabot, Vermont
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Remembering the Arizona
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Yarn for Distaff Day
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Mandarin duck, Richmond Park, London, England
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Cenote near Puerto Aventuras, Mexico
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Miravet, Catalonia, Spain
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Bask in the glow—It s World Turtle Day
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Astrotourism at its finest
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Mount Field National Park, Tasmania, Australia
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From the mind of Frank Gehry
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Palmyra Atoll National Wildlife Refuge
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In Texas, even the riverbend is big
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Preveli Gorge
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Black History Month
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Camels at Jaisalmer, Rajasthan, India
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Happy Canada Day!
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A river runs through it
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Great cormorants
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Schönbrunn Palace Park, Vienna, Austria
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International Day of Friendship
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World Bicycle Day
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Virgin Islands National Park established
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Veterans Day
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National Frog Month
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Hidden beauty in Thailand
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World Art Day
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It s Asian Pacific American Heritage Month
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World Architecture Day
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