Did Neolithic humans build this structure to celebrate Pi Day? Not likely. Pi Day is a relatively recent phenomenon—invented by a physicist in 1988 and designated by Congress a national holiday in 2009. But it"s already almost certainly the most popular holiday celebrating a mathematical constant. While Pi Day is a young tradition, the number π (pi) itself has been a fascination since antiquity, when it was first calculated as the ratio of a circle"s circumference to its diameter.
Pi Day
Today in History
More Desktop Wallpapers:
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Keep calm and drive on (slowly)
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Exploring the wilder side of New York
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Three cheers for polar bears!
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I am the walrus
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Poinsettia Day
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Get on your bike and ride
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Spring equinox
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Earth Day and National Park Week
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Desert rose of Qatar
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Ravens
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Clouds over the River of Grass
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How lovely are your branches
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Space-age style by the sea
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Aw shucks, it’s oyster season in Galway
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Winterpret on ice
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Our Lady of the Rocks
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A throng of ice and spires
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Oud-West, Amsterdam, Netherlands
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Sunrise at Grand Teton National Park, Wyoming
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National Park Service Founders Day
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Guiding ships to safety
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It s National Mushroom Month!
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A city, a cliff, a canyon…and cheese
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A cozy winter village
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International Lighthouse Weekend
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Everglades National Park marks 90 years
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Pont Rouge
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A glimpse of the Blue Forest
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Easter
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A misty morning in Brazil
Bing Wallpaper Gallery

