Sphere – Introduction

A sphere is a perfectly round solid figure bounded by a curved surface such that every point on the surface is at an equal distance from the centre. 

It is a perfectly round geometrical object in three-dimensional space and examples include a football, an orange, etc.  The distance from the centre to the sphere’s outer surface is called its radius.

The shape obtained when a sphere is cut through the middle into two halves is called a hemisphereA hemisphere is half the Earth's surface. The four hemispheres are the Northern and Southern hemispheres, divided by the equator (0° latitude), and the Eastern and Western hemispheres, divided by the... More. A hemisphere is the half of a sphere and has a curved surface and a flat base.