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| ==Origin== | | ==Origin== |
− | [http://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English] ''cenyth'', ''senyth'', from Middle French ''cenit'', from Medieval Latin, from Old Spanish ''zenit'', ''modification'' of Arabic ''samt'' (''al-ra's'') way (over one's head) | + | [https://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English] ''cenyth'', ''senyth'', from Middle French ''cenit'', from Medieval Latin, from Old Spanish ''zenit'', ''modification'' of Arabic ''samt'' (''al-ra's'') way (over one's head) |
− | *[http://en.wikipedia.org/wiki/14th_century 14th Century] | + | *[https://en.wikipedia.org/wiki/14th_century 14th Century] |
− | The word "zenith" derives from the inaccurate [[reading]] of the Arabic expression سمت الرأس (samt ar-ra's), meaning "[[direction]] of the head" or "[[path]] above the head", by Medieval Latin scribes in the [http://en.wikipedia.org/wiki/Middle_Ages Middle Ages] (during the 14th century), possibly through Old Spanish. It was reduced to 'samt' ("[[direction]]") and miswritten as 'senit'/'cenit', as the "m" was misread as an "ni". Through the Old French 'cenith', 'zenith' first appeared in the 17th century. | + | The word "zenith" derives from the inaccurate [[reading]] of the Arabic expression سمت الرأس (samt ar-ra's), meaning "[[direction]] of the head" or "[[path]] above the head", by Medieval Latin scribes in the [https://en.wikipedia.org/wiki/Middle_Ages Middle Ages] (during the 14th century), possibly through Old Spanish. It was reduced to 'samt' ("[[direction]]") and miswritten as 'senit'/'cenit', as the "m" was misread as an "ni". Through the Old French 'cenith', 'zenith' first appeared in the 17th century. |
| ==Definitions== | | ==Definitions== |
− | *1: the point of the [http://en.wikipedia.org/wiki/Celestial_sphere celestial sphere] that is directly opposite the [http://en.wikipedia.org/wiki/Nadir nadir] and vertically above the [[observer]] — see [http://en.wikipedia.org/wiki/Azimuth azimuth] illustration | + | *1: the point of the [https://en.wikipedia.org/wiki/Celestial_sphere celestial sphere] that is directly opposite the [https://en.wikipedia.org/wiki/Nadir nadir] and vertically above the [[observer]] — see [https://en.wikipedia.org/wiki/Azimuth azimuth] illustration |
| *2: the highest [[point]] reached in the heavens by a celestial body | | *2: the highest [[point]] reached in the heavens by a celestial body |
| *3: [[culminating]] [[point]] : [[acme]] <at the zenith of his powers — John Buchan> | | *3: [[culminating]] [[point]] : [[acme]] <at the zenith of his powers — John Buchan> |
| ==Description== | | ==Description== |
− | The '''zenith''' is an [[imaginary]] point directly "above" a particular location, on the imaginary [http://en.wikipedia.org/wiki/Celestial_sphere celestial sphere]. "Above" means in the [[vertical]] direction opposite to the apparent [[gravitational]] force at that location. The opposite direction, i.e. the direction in which gravity pulls, is toward the [http://en.wikipedia.org/wiki/Nadir nadir]. | + | The '''zenith''' is an [[imaginary]] point directly "above" a particular location, on the imaginary [https://en.wikipedia.org/wiki/Celestial_sphere celestial sphere]. "Above" means in the [[vertical]] direction opposite to the apparent [[gravitational]] force at that location. The opposite direction, i.e. the direction in which gravity pulls, is toward the [https://en.wikipedia.org/wiki/Nadir nadir]. |
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| The term ''zenith'' is sometimes used to refer to the highest [[point]] reached by a celestial body during its apparent [[orbit]] around a given point of [[observation]]. This sense of the word is often used to [[describe]] the location of the [[Sun]] ("The sun reached its zenith..."), but to an [[astronomer]] the sun doesn't have its own zenith, and is at the zenith only if it is directly overhead. | | The term ''zenith'' is sometimes used to refer to the highest [[point]] reached by a celestial body during its apparent [[orbit]] around a given point of [[observation]]. This sense of the word is often used to [[describe]] the location of the [[Sun]] ("The sun reached its zenith..."), but to an [[astronomer]] the sun doesn't have its own zenith, and is at the zenith only if it is directly overhead. |
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| In a scientific [[context]], the zenith is the direction of [[reference]] for measuring the zenith angle, the angle between a direction of interest (e.g., a star) and the local zenith. | | In a scientific [[context]], the zenith is the direction of [[reference]] for measuring the zenith angle, the angle between a direction of interest (e.g., a star) and the local zenith. |
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− | In [[astronomy]], the altitude in the [http://en.wikipedia.org/wiki/Horizontal_coordinate_system horizontal coordinate system] and the zenith angle are [[complementary]] [[angles]], with the [[horizon]] perpendicular to the zenith. The astronomical [http://en.wikipedia.org/wiki/Meridian_(astronomy) meridian] is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the [http://en.wikipedia.org/wiki/Celestial_pole celestial poles]. | + | In [[astronomy]], the altitude in the [https://en.wikipedia.org/wiki/Horizontal_coordinate_system horizontal coordinate system] and the zenith angle are [[complementary]] [[angles]], with the [[horizon]] perpendicular to the zenith. The astronomical [https://en.wikipedia.org/wiki/Meridian_(astronomy) meridian] is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the [https://en.wikipedia.org/wiki/Celestial_pole celestial poles]. |
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| Zenith is also used to determine the time of Dhuhr (midday) prayer by Muslims which is when the sun passes the zenith. | | Zenith is also used to determine the time of Dhuhr (midday) prayer by Muslims which is when the sun passes the zenith. |
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| [[Category: Astronomy]] | | [[Category: Astronomy]] |