The placement of 
points on a sphere so as to minimize the maximum distance
of any point on the sphere from the closest one of the 
points.
Spherical Covering
See also
Spherical Code, Spherical DesignExplore with Wolfram|Alpha
References
Hardin, R. H.; Sloane, N. J. A. S.; and Smith, W. D. Spherical Codes. In preparation. http://www.research.att.com/~njas/coverings/.Referenced on Wolfram|Alpha
Spherical CoveringCite this as:
Weisstein, Eric W. "Spherical Covering." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/SphericalCovering.html