# Sphere

A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle, which is in two dimensions, a sphere is the set of points which are all the same distance r from a given point in space. This distance r is known as the "radius" of the sphere, and the given point is known as the center of the sphere. The maximum straight distance through the sphere is known as the "diameter". It passes through the center and is thus twice the radius.

In mathematics, a careful distinction is made between the sphere (a two-dimensional surface embedded in three-dimensional Euclidean space) and the ball (the interior of the three-dimensional sphere).

### Other articles related to "sphere":

Cubes in Relation To Spheres
... For every sphere there are multiple cuboids that may be inscribed within the sphere ... The largest cuboid which can be inscribed within a sphere is a cube ...
Geotrekking - Navigation Equations - Trilateration
... Satellite position and pseudorange determines a sphere centered on the satellite with radius equal to the pseudorange ... to estimate receiver position based on the intersection of three sphere surfaces so determined ... In the usual case of two intersections of three sphere surfaces, the point nearest the surface of the sphere corresponding to the fourth satellite is chosen ...
1 33 Honeycomb - Kissing Number
... of this polytope corresponds to the center of a 6-sphere in a moderately dense sphere packing, in which each sphere is tangent to 70 others the best known for 7 ...
Kline Sphere Characterization
... In mathematics, a Kline sphere characterization, named after John Robert Kline, is a topological characterization of a two-dimensional sphere in terms of what ... A simple closed curve in a two-dimensional sphere (for instance, its equator) separates the sphere into two pieces upon removal ... If one removes a pair of points from a sphere, however, the remainder is connected ...
Marcus Theory - Outer Sphere Electron Transfer
... or the ligands in complexes, are tightly bound and constitute the "inner sphere" ... The free solvent molecules constitute the "outer sphere" ... Outer sphere redox reactions do not change the inner sphere, no bonds are made nor broken ...

### Famous quotes containing the word sphere:

In science, as in art, and, as I believe, in every other sphere of human activity, there may be wisdom in a multitude of counsellors, but it is only in one or two of them.
Thomas Henry Huxley (1825–95)

It is in the nature of allegory, as opposed to symbolism, to beg the question of absolute reality. The allegorist avails himself of a formal correspondence between “ideas” and “things,” both of which he assumes as given; he need not inquire whether either sphere is “real” or whether, in the final analysis, reality consists in their interaction.
Charles, Jr. Feidelson, U.S. educator, critic. Symbolism and American Literature, ch. 1, University of Chicago Press (1953)

One concept corrupts and confuses the others. I am not speaking of the Evil whose limited sphere is ethics; I am speaking of the infinite.
Jorge Luis Borges (1899–1986)