Though it has been retired since 2018, the observations made by NASA's Kepler Space Telescope during its decade-long mission continue to allow researchers to identify new worlds in our galaxy. The latest to make headlines is an Earth-sized exoplanet that rotates around its dwarf star in just 3.14 days. The similarity to the close approximation of the mathematical constant pi — the ratio between a circle's circumference and its diameter — has earned the alien world the nickname "Pi planet."