Listen now (7 mins) | Astronomers recently discovered an a planet the size of earth. Though it looks similar to earth, it has no other features in common with it and it was found to be uninhabitable too. Since this planet completes its orbit around its star in 3.14 days, it was named after the mathematical constant Pi, whose value is 3.14. Its real name was K2-315b, but, for convenience, it is called by the Greek letter Pi. The Pi planet is also called Pi Earth.