Wat Phra Ngam, Ayutthaya Historical Park, Thailand

A piece of pi. Happy Pi Day!

They say the only constant in life is change. In mathematics, however, there are many constants, and today, we're celebrating perhaps the most famous of them all: pi. This tasty-sounding constant is the ratio of a circle's circumference to its diameter, approximately 3.14159. Every March 14, mathematics fans across the world get baking to mark Pi Day—a celebration of both the mathematical constant π and its delicious homophone, pie. It began in 1988, when physicist Larry Shaw connected the date (3/14) with the first three digits of this constant. Today, mathematicians and enthusiasts celebrate Pi Day with pie eating and pi reciting. Did you know that when your clock strikes 1:59 today, you will be three decimal places closer to the real value of pi? Pi is everywhere, even in nature. Pictured here is a bodhi tree in the shape of the pi symbol at Wat Phra Ngam, a temple in Ayutthaya, Thailand. Whether you're a math geek or just in it for the treats, Pi Day is for everyone to enjoy!