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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Reflections on Memorial Day
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International Lighthouse Weekend
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Burrowing owls
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An historic forest
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Happy Cinco de Mayo!
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Casting a vote for women s history
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Joan charges Riverside Park
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A peek at an explosive peak
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Hues of Hokkaido
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Seville celebrates first world tour
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What s going on in this sky?
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Fiddlehead fern fronds
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Craters of the Moon centennial
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Mekong River Delta, Long An, Vietnam
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Menton, France
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Old city wall of Hwaseong Fortress, Suwon, South Korea
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Three cheers for polar bears!
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And you thought moths were boring
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Manatee Awareness Month
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Veterans Day
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Albion Falls, Hamilton, Ontario, Canada
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National Audubon Society s Christmas Bird Count
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Khao Sok National Park in Thailand
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Tall, taller, tallest
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Carnival of Venice
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Sitting down and taking a stand
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Mesquite Flat Sand Dunes in Death Valley National Park, California
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Apples ready for harvest in Minnesota
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The Tour de France begins
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Let’s go foraging
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