Sphere

A sphere is a three-dimensional geometric shape whose surface is made up of all the points that are the same distance from one central point. This distance is called the radius. Unlike a circle, which is a flat two-dimensional shape, a sphere has length, width and depth. A ball is a familiar example of an object that is approximately spherical, although real balls may not be perfect spheres.

A sphere has no edges, corners or flat faces, so its surface is continuous and curved. Any straight line passing through the center and joining two points on the surface is called a diameter. The diameter is twice as long as the radius. Spheres are found in many areas of everyday life and science.

Some fruits, bubbles, marbles and planets have shapes that are close to spherical. In mathematics, a sphere can be described precisely using its radius. Its surface area is calculated with the formula 4 × π × r², while its volume is 4/3 × π × r³, where r represents the radius and π is a mathematical constant approximately equal to 3.14.

A sphere looks the same from every direction when viewed from its center because of its high degree of symmetry. It also has no preferred direction on its surface: every point is equally far from the center. These properties make the sphere an important shape in geometry, physics and the study of many natural objects.