Concept
Celestial sphere
Overview
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
The celestial sphere is a conceptual tool used in spherical astronomy to specify the position of an object in the sky without consideration of its linear distance from the observer. The celestial equator divides the celestial sphere into northern and southern hemispheres.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
Possible passages
Found by search and not yet checked by a person; they may only mention the idea in passing.
Such was the mind and thought of God in the creation of time. The sun and moon and five other stars, which are called the planets, were created by him in order to distinguish and preserve the numbers of time; and when he had made their several bodies, he placed them in the orbits in which the circle of the other was revolving,—in seven orbits seven stars. First, there was the moon in the orbit nearest the earth, and…
Plato, Timaeus
States what Celestial sphere is; the author is tied to Celestial sphere in the knowledge graph.
Indeed, when two things are simultaneously raised by one and the same power, the smaller quantity must of course yield more readily than the greater to the impulsive force by which they are constrained; and hence, the one is called _heavy_ and gravitating downwards, the other _light_ and tending upwards. The same thing also is observable in what we ourselves do, who inhabit this place [the earth].
Plato, The works of Plato
States what Celestial sphere is; the author is tied to Celestial sphere in the knowledge graph.
Pythagoras says that, as the celestial sphere is distributed into five zones, into the same number is the terrestrial; which zones are the arctic and antarctic, the summer and winter tropics (or temperate zones), and the equinoctial; the middle of which zones equally divides the earth and constitutes the torrid zone; but that portion which is in between the summer and winter tropics is habitable, by reason the air…
Plutarch, Complete Works of Plutarch — Volume 3
States what Celestial sphere is; names Celestial sphere.
Related ideas
- Aristotelian physics
- Giordano Bruno
- Anaxagoras
- Geometry
- Moon
- Infinity
- Plato
- Ptolemy
- Heliocentrism
- Solar System
- Abstraction
- Aristotle
- Johns Hopkins University Press
- Earth's rotation
- Hellenistic period
- Celestial pole
- Eudoxus of Cnidus
- Astronomy
- Astronomer
- Classical element
- Aristarchus of Samos
- Geocentrism
- Earth
- Ecliptic
Place in the tradition
Part of Cosmology.