March 14 marks the 20th anniversary of Pi Day, an international holiday founded by the Exploratorium, San Francisco, California, to celebrate the irrational number (it also happens to be Albert Einstein’s birthday).
The highlight of the festivities is the annual Pi Procession to the Pi Shrine, a small brass plate engraved with pi to a hundred digits placed at the exact center of a circular classroom on the first Pi Day in 1988. Participants carry numerals (3.145926535…) and chant the Pi Day song. Afterward, guests are served—what else? Pie.
Other activities will include spin art, math puzzles, and a demonstration by a world champion pizza tosser. A virtual celebration will also take place in the Exploratorium’s Second Life museum, ’Splo.
About the image: Staff physicist Larry Shaw leads the annual Pi Procession. Photo by Amy Snyder. © The Exploratorium