Happy Pi Day! We hope you have the chance to enjoy the tasty kind of pie today – in the meantime, here’s a pi “appetizer”.

To a surveyor, pi is a key concept that undergirds everything, because surveying occurs on a sphere. Specifically, all boundaries must take into consideration the curve of the earth (and any distortions of that curve, as well as elevation).

Today has been officially known as π (Pi) day since 2009 when the US House of Representatives passed a non-binding resolution recognizing March 14 as National Pi Day. Aside from being a great day to eat pie, it’s a great day to celebrate how mathematics, and one specific concept, has shaped our world.