(cosmology) Hubble volume

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.

A unified body or collection of knowledge regarding a specific subject.

(astronomy) An abstract sphere of infinite radius which serves as the imaginary backdrop for celestial objects, and of which the visible sky is one hemisphere.

A hypothetical system of orbiting solar power satellites meant to completely encompass a star and capture its entire energy output. / (science fiction) A solid shell of matter enclosing a star.

(topology, complex analysis) The complex numbers extended with the number ∞; the complex plane (representation of the complex numbers as a Euclidean plane) extended with a single idealised point at infinity and consequently homeomorphic to a sphere in 3-dimensional Euclidean space.

(mythology) A continuous, glorious, harmonious set of sounds that are not audible to ordinary human beings, produced by the movement of the celestial bodies. / (figuratively) Sublime, mysterious music.

plural of homology sphere

(topology) A manifold whose homology is the same as that of some sphere of the same dimension