plural of unit sphere

plural of Bloch sphere

plural of Hill sphere

plural of celestial sphere

plural of crystal sphere

plural of photon sphere

plural of Klerksdorp sphere

plural of Alexander horned sphere

The area (literal or figurative) influenced by a country, person, etc.

(astronomy, geography) The celestial or terrestrial sphere when its axis is oblique to the horizon of the place; or as it appears to an observer at any point on the earth except the poles and the equator.