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
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It s Slovenia s Independence and Unity Day
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Sunrise at Grand Teton National Park, Wyoming
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Manatee Appreciation Day
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Christmas star lanterns, Germany
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Chestnut-eared aracari in the Pantanal, Brazil
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Atlanta Botanical Garden
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The moon rises for Mid-Autumn Festival
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Mount Segla, Senja Island, Norway
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Burchells zebras for International Zebra Day
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A giant relic in Java
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The Twin Cities celebrate Pride
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Four little birds sitting in a tree…
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Gauchos showcase Argentina’s independent spirit
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Wild scene on the Merced River
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Collared aracari in Costa Rica
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The cycle begins anew
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National Gardening Week
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The Grand Départ: Tour de France begins
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World Teachers Day
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A gentle wind fills this sail
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Paralympic Games begin in Paris
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The Easter Bunny’s story
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Ocean City, Maryland, at sunrise
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Three cheers for polar bears!
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Mountains fit for a queen
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Nature Photography Day
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An emerald isle of the Emerald Isle
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Jane’s Carousel delights
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A special day for a special cat
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Happy Fathers Day!
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