Large-scale celebration of Pi Day began in 1988, mostly through the efforts of physicists Larry Shaw and Ron Hipschmann at the San Francisco Exploratorium. The Exploratorium still runs Pi Day events 26 years later, including Pi-themed processions and pie for dessert. In 2009, Pi Day became semi-official through a vote by the House of Representatives. (They did a better job with Pi than did Indiana, who almost legislated it to be 3.2.)
mikejuk writes to let us know that today is Pi Day — 3/14 in American date notation. He writes,
"This year, it feels as though we aren't celebrating alone. For the first time, it looks as if momentum has built up to the point where people have heard about Pi Day. There are even attempts to sell you Pi-related items as if it was a real holiday. But there is always some one to spoil the party so what ever you do to celebrate don't miss Vi Hart's Anti-Pi Rant video."
Thus begins the yearly debate over Pi Day vs. Tau Day
(June 28). Phil Plait has a post defending Pi Day's honor
, and MIT isn't holding back their Pi Day celebrations
The best way to celebrate Pi Day is to get together with some friends and talk math over a pie. You could even go for a pizza pie, since a pizza with radius 'z' and height 'a' has volume = pi * z * z * a. If you'd care for a game, head over to the Pi Day Challenge, which features a series of pi-related logic puzzles. Or just spend the day learning about pi.
Cool pi facts: Pi is currently known to about 10 billion decimal places. You can calculate pi using the Fibonacci sequence. A few years ago, Steven Rochen mapped the digits of pi to musical notes and turned it into a violin solo (video). Others have made music from pi as well. Mankind didn't know the first hundred digits of pi until the year 1701. How many digits of pi can you recite? The record for memorization currently stands at 67890 digits. The record for reciting pi while juggling three balls is just under 10,000.