Did you know today is Pi in the Sky Day? There will be skywriting planes above the San Francisco Bay Area which will create "Pi in the Sky," which they say will be the world’s largest art installation. It's happening today, between 11:45 am and 1:30 pm.
Five synchronized skywriting planes will draw the first 1,000 digits of the infinite sequence of pi (π) – the ratio of a circle's circumference to its diameter at 10,000 feet in the air. Using dot-matrix skywriting technology, the aerial numbers will measure a quarter-mile tall and extend more than 100 miles. Follow along on twitter @piZone_dot_org.
Read more here.