Riemann Sphere

The Riemann sphere is a model of the extended complex plane, the ordinary complex numbers together with a single additional point at infinity, named for Bernhard Riemann and arising from his work on complex analysis in the 1850s. The point at infinity plays a role analogous to the role zero plays for very small numbers, allowing expressions such as one divided by zero to be given a well-defined meaning as that point. The sphere can be constructed from the complex plane by stereographic projection, a map that wraps the whole infinite plane around a sphere so that every point of the plane, and the single point at infinity, corresponds to exactly one point on the sphere's surface. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/