Circular agricultural fields in Morgan County, Colorado
© Jim Wark/Getty Image
It’s 3.14159 Day. Rocky mountain pi
It’s Pi Day, the day we celebrate the mathematical constant π. This day was chosen since today’s date expressed numerically (in US format) matches the number’s first digits, 3.14. Pi represents the ratio of a circle’s circumference to its diameter. It can be used to compute the area and circumference of a circle, such as the crop patterns we're looking at here in Colorado. (Who said maths wasn't useful in the real world?) Many towns, schools, and museums mark the day with festivities based around mathematics and, of course, serving pie. We can’t think of a more delicious way to study geometry.
Related Images
Leopard snoozing in a tree in Namibia
Wildflowers in bloom at Lost Dutchman State Park in Arizona
Water wheel in the Tashkurgan Grassland, Tashkurgan Tajik Autonomous County, Xinjiang, China
Australian sea lion (Neophoca cinerea) lying on a bed of sea grass in Carnac Island, Western Australia
Sunset at Counts Point in West MacDonnell Ranges, Northern Territory, Australia
An old farm in the Shetland Islands, Scotland
Lake Dobson in Mount Field National Park of Tasmania
Almond orchards in bloom, Sacramento Valley, California
Bing Today Images
Mute swan with chicks, Hesse, Germany
Mar 13, 2026
Gran Paradiso National Park, Piedmont, Italy
Mar 13, 2025
Lesser flamingos flying over Lake Magadi, Kenya
Mar 13, 2024
European hare, Netherlands
Mar 13, 2022
The Circle Bridge in Copenhagen, Denmark
Mar 13, 2020
Enhanced image of a cross-section of a pine stem
Mar 13, 2017
