Every year on March 14, many people eat pie in honor of Pi Day. Mathematically
speaking, pi (π) is the ratio of a circle’s circumference (the distance around
the outside) to its diameter (the length from one side of the circle to the
other, straight through the center). That means if you divide the
circumference of any circle by its diameter, the solution will always be pi,
which is roughly 3.14—hence March 14, or 3/14. But pi is an
irrational number, which means that the numbers after the decimal
point never end. With the help of computers, mathematicians have determined
trillions of digits of pi.
To celebrate Pi Day, check out this slideshow of circular microbes,
research organisms, and
laboratory tools (while you enjoy your pie, of course!). To explore more
scientific photos, videos, and illustrations, visit our
image and video gallery.