It was back in 1988 that Exploratorium physicist Larry Shaw got a crazy idea. He wanted to celebrates his favorite irrational number, pi.
As any high school student has learned, pi is the ratio of a circle's circumference to its diameter.
Video: How to measure pi using a real pie
The equation results in a number that begins with 3.14, but the result is actually infinite. Scientists have calculated up to 1.24 trillion digits of pi so far.
About thirty years ago, Shaw saw an opportunity to have some fun with the number, so he organized a circular walk with the public and staff. The event ended with a serving of pie.
The Exploratorium has made it an annual celebration. And it has caught on in a big way. In 2009, the House of Representatives declared March 14 as National Pi Day.
Shaw died August 2017 and for years the Exploratorium held activities and lectures, a pi procession and a serving of pie.
This year the Exploritorium is closed out of caution to slow the spread of COVID-19, but you can learn more about Pi day through a webcast on the Exploritorium website here.