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Definition: Celestial Sphere |
Celestial SphereNoun1. The apparent surface of the imaginary sphere on which celestial bodies appear to be projected. Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
| Domain | Definition |
Geography | An imaginary sphere of infinite radius concentric with the earth, on which all celestial bodies except the earth are imagined to be projected. Source: European Union. (references) |
Space | An immense sphere surrounding Earth, to which the fixed stars seen at night appear to be attached. Although strictly speaking such a sphere does not exist, it is often used as a convenient tool for mapping the position of stars and other heavenly bodies. In a similar way, although it is clear that the apparent rotation of the celestial sphere is really due to the Earth rotating around its axis, that rotation is often used for convenient description of apparent motions such as the rising and setting of stars. (references) |
Source: compiled by the editor from various references; see credits. | |
(From Wikipedia, the free Encyclopedia)
In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of "gigantic radius", concentric with the Earth. All objects in the sky can be thought of as lying upon the sphere. Projected, from their corresponding terran equivalents, are the celestial equator and the celestial poles.
Many ancient societies believed that the stars were equidistant from the Earth and that this sphere was a real model of the universe. This model is a useful abstraction, but not correct. Everything we see in the sky is so very far away, that their distances are impossible to gauge just by looking at them. Since their distances are indeterminate, you only need to know the direction toward the object to locate it in the sky. In this sense, the celestial sphere model is a very practical tool for positional astronomy.
As the Earth rotates on its axis, the objects on the celestial sphere will appear to rotate around the celestial poles every 24 hours, this is diurnal motion. For example the Sun will typically appear to rise in the east and set in the west, as will the stars, planets and moon. On each subsequent night, a given star will rise ~4 minutes earlier than it rose the previous night. Superimposed on diurnal motion is; intrinsic motion as the objects change their relative positions, with respect to Earth. For example, over the course of a year the Sun, relative to the background stars, will follow a bisecting great circle (known as the ecliptic).
See also: prograde and retrograde motion
The celestial sphere is divided by projecting the equator into space. This divides the sphere into the north celestial hemisphere and the south celestial hemisphere. Likewise, one can locate the Celestial Tropic of Cancer, Celestial Tropic of Capricorn, North Celestial Pole, and South Celestial Pole.
As the earth rotates from west to east, the celestial sphere appears to rotate from east to west. Some stars are sufficiently near the celestial poles such that they appear to hover just above the horizon, such stars are circumpolar.
The directions toward various objects in the sky can be quantified by constructing a celestial coordinate system.
see also: circle of latitude, equinox, Moon, solstice, Sun, zodiac
See also: Geocentric universe
External Link
- SkyandTelescope.com SkyChart
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Celestial sphere."
Synonyms: Celestial SphereSynonyms: empyrean (n), firmament (n), heavens (n), sphere (n), vault of heaven (n), welkin (n). (additional references) |
Crosswords: Celestial Sphere |
| English words defined with "celestial sphere": apex, apex of the sun's way, armillary sphere ♦ celestial equator, celestial horizon, celestial latitude, celestial longitude, celestial point, celestial pole, Celestial poles ♦ Dec, declination, direct ♦ equinoctial, equinoctial circle, equinoctial line ♦ Ground of the heavens ♦ horizon, hour circle ♦ Planisphere, pole, Poles of the heavens ♦ Ra, retrograde, right ascension ♦ solar apex ♦ vertical circle. (references) |
| Specialty definitions using "celestial sphere": antisolar point, apparent position, astre fictif, astrometric position ♦ celestial coordinates, celestial triangle, circle of latitude, circle of longitude ♦ ecliptic pole ♦ First point in Aries ♦ galactic pole, geoidal horizon ♦ mean position, meteor path ♦ navigational triangle ♦ Plane of the ecliptic ♦ solstitial colure ♦ true position. (references) |
| Domain | Title |
Books | |
Source: compiled by the editor from various references; see credits. | |
| The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com. |
| Expression | Frequency per Day |
celestial sphere | 31 |
| Source: compiled by the editor from various references; see credits. | |
| Language | Translations for "celestial sphere"; alternative meanings/domain in parentheses. | |
Danish | himmelsfære, himmelhvælvingen. (various references) | |
Dutch | hemelbol. (various references) | |
Finnish | taivaanpallo. (various references) | |
French | sphère céleste. (various references) | |
German | Himmelskugel. (various references) | |
Hungarian | éggömb, egek. (various references) | |
Indonesian | falak. (various references) | |
Italian | sfera celeste assoluta. (various references) | |
Japanese Kanji | 天球 . (various references) | |
Japanese Katakana | てんきゅう (rain from a cloudless sky). (various references) | |
Pig Latin | elestialcay eresphay.(various references) | |
Portuguese | esfera celeste. (various references) | |
Spanish | espera celeste. (various references) | |
Swedish | himmelssfären, himmelssfär. (various references) | |
Thai | สวรรค์ (nirvana, Zion). (various references) | |
| Source: compiled by the editor from various translation references. | ||
| Language | Period | Translations |
| Latin | 500 BCE-Modern | caverna, cavernas, cavernis. (various references) |
| Source: compiled by the editor from various references. | ||
Misspellings | |
"Celestial Sphere" is suggested in spellcheckers for the following: celestail sphere. (additional references) | |
| Source: compiled by the editor, based on several corpora (additional references). | |
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "a-c-e-e-e-e-h-i-l-l-p-r-s-s-t" | |
-2 letters: steeplechaser. | |
-3 letters: steeplechase. | |
-4 letters: sphalerites. | |
-5 letters: cartelises, celestials, chisellers, clipsheets, easterlies, heelpieces, hillcrests, palletises, pelletises, preachiest, preethical, preselects, psalteries, replicases, replicates, scheelites, shapeliest, specialest, sphalerite. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
