Wat Phra Ngam, Ayutthaya Historical Park, Thailand

© boonchai wedmakawand/Alam

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. Represented by the symbol π, this tasty-sounding number 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 with a pie. It began in 1988, when physicist Larry Shaw connected the date (3/14) with the first three digits of π. 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 which has grown over an arch into 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!