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| ==Origin== | | ==Origin== |
| Medieval Latin ''culminatus'', past participle of ''culminare'', from Late Latin, to crown, from [[Latin]] ''culmin''-, ''culmen'' top | | Medieval Latin ''culminatus'', past participle of ''culminare'', from Late Latin, to crown, from [[Latin]] ''culmin''-, ''culmen'' top |
− | *[http://en.wikipedia.org/wiki/17th_century 1647] | + | *[https://en.wikipedia.org/wiki/17th_century 1647] |
| ==Definitions== | | ==Definitions== |
− | *1:of a [[celestial]] body : to reach its highest [http://en.wikipedia.org/wiki/Altitude altitude]; also : to be directly overhead | + | *1:of a [[celestial]] body : to reach its highest [https://en.wikipedia.org/wiki/Altitude altitude]; also : to be directly overhead |
| *2a : to rise to or form a [[summit]] | | *2a : to rise to or form a [[summit]] |
| :b : to reach the highest or a [[climactic]] or decisive [[point]] | | :b : to reach the highest or a [[climactic]] or decisive [[point]] |
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| <center>For lessons on the [[topic]] of '''''Culmination''''', follow [https://nordan.daynal.org/wiki/index.php?title=Category:Culmination '''''this link'''''].</center> | | <center>For lessons on the [[topic]] of '''''Culmination''''', follow [https://nordan.daynal.org/wiki/index.php?title=Category:Culmination '''''this link'''''].</center> |
| ==Description== | | ==Description== |
− | In [[astronomy]], the '''culmination''' of a [[planet]], [[star]], [http://en.wikipedia.org/wiki/Constellation constellation], etc. is the altitude (or elevation angle) reached when the object transits over an [[observer]]'s [http://en.wikipedia.org/wiki/Meridian_(astronomy) meridian]. | + | In [[astronomy]], the '''culmination''' of a [[planet]], [[star]], [https://en.wikipedia.org/wiki/Constellation constellation], etc. is the altitude (or elevation angle) reached when the object transits over an [[observer]]'s [https://en.wikipedia.org/wiki/Meridian_(astronomy) meridian]. |
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− | During a [http://en.wikipedia.org/wiki/Sidereal_day sidereal day], an astronomical object will cross the meridian twice: once at its upper culmination, when it is at its highest point as seen from the [[earth]], and once at its lower culmination, its lowest point. Often, culmination is used to mean upper culmination. | + | During a [https://en.wikipedia.org/wiki/Sidereal_day sidereal day], an astronomical object will cross the meridian twice: once at its upper culmination, when it is at its highest point as seen from the [[earth]], and once at its lower culmination, its lowest point. Often, culmination is used to mean upper culmination. |
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− | The altitude of an object in degrees at its upper culmination is equal to (90 − L + D), where L is the [[observer]]'s [[latitude]] and D is the object's [http://en.wikipedia.org/wiki/Declination declination]. | + | The altitude of an object in degrees at its upper culmination is equal to (90 − L + D), where L is the [[observer]]'s [[latitude]] and D is the object's [https://en.wikipedia.org/wiki/Declination declination]. |
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− | Generally, the [[sun]] is visible at its upper culmination (at noon) and not visible at its lower culmination (at midnight). But during winter near the [http://en.wikipedia.org/wiki/North_Pole North Pole], the sun is below the [[horizon]] at both of its culminations. In most of the northern hemisphere, [http://en.wikipedia.org/wiki/Polaris Polaris], the "North Star", and the rest of the stars of the constellation [http://en.wikipedia.org/wiki/Ursa_Minor Ursa Minor] can be seen to rotate around the [http://en.wikipedia.org/wiki/Celestial_pole celestial pole] and are all visible at both culminations, as long as the sky is [[dark]] enough. Such stars, which never set at the [[observer]]'s location are described as being [http://en.wikipedia.org/wiki/Circumpolar_star circumpolar]. | + | Generally, the [[sun]] is visible at its upper culmination (at noon) and not visible at its lower culmination (at midnight). But during winter near the [https://en.wikipedia.org/wiki/North_Pole North Pole], the sun is below the [[horizon]] at both of its culminations. In most of the northern hemisphere, [https://en.wikipedia.org/wiki/Polaris Polaris], the "North Star", and the rest of the stars of the constellation [https://en.wikipedia.org/wiki/Ursa_Minor Ursa Minor] can be seen to rotate around the [https://en.wikipedia.org/wiki/Celestial_pole celestial pole] and are all visible at both culminations, as long as the sky is [[dark]] enough. Such stars, which never set at the [[observer]]'s location are described as being [https://en.wikipedia.org/wiki/Circumpolar_star circumpolar]. |
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| These three examples illustrate all three cases, dependent on the latitude of the observer and the declination of the celestial body. | | These three examples illustrate all three cases, dependent on the latitude of the observer and the declination of the celestial body. |
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− | *the object is above the horizon even at its lower culmination: it is circumpolar; i.e. if |declination + latitude| > 90° (i.e. if in [http://en.wikipedia.org/wiki/Absolute_value absolute value] the declination is more than the colatitude, in the corresponding hemisphere) | + | *the object is above the horizon even at its lower culmination: it is circumpolar; i.e. if |declination + latitude| > 90° (i.e. if in [https://en.wikipedia.org/wiki/Absolute_value absolute value] the declination is more than the colatitude, in the corresponding hemisphere) |
| *the object is below the horizon even at its upper culmination; i.e. if |declination − latitude| > 90° (i.e. if in absolute value the declination is more than the colatitude, in the opposite hemisphere) | | *the object is below the horizon even at its upper culmination; i.e. if |declination − latitude| > 90° (i.e. if in absolute value the declination is more than the colatitude, in the opposite hemisphere) |
| *the upper culmination is above, and the lower below the horizon, so the body is observed to rise and set daily; in the other cases (i.e. if in absolute value the declination is less than the colatitude) | | *the upper culmination is above, and the lower below the horizon, so the body is observed to rise and set daily; in the other cases (i.e. if in absolute value the declination is less than the colatitude) |
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| The third case applies for objects in a part of the full sky equal to the cosine of the [[latitude]] (at the [[equator]] it applies for all objects, the [[sky]] turns around the horizontal north-south line; at the poles it applies for none, the sky turns around the vertical line). The first and second case each apply for half of the remaining sky. | | The third case applies for objects in a part of the full sky equal to the cosine of the [[latitude]] (at the [[equator]] it applies for all objects, the [[sky]] turns around the horizontal north-south line; at the poles it applies for none, the sky turns around the vertical line). The first and second case each apply for half of the remaining sky. |
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− | The time from one upper culmination to the next is approximately 24 hours, and from an upper to a lower culmination is approximately 12 hours. The movement of the [[Earth]] on its [[orbit]] and proper motion of the celestial body affect the time between successive upper culminations of the body. Because of the proper and improper motions of the [[sun]], one solar day (the time between two upper culminations of the sun) is longer than one [http://en.wikipedia.org/wiki/Sidereal_day sidereal day] (the time between two like culminations of any fixed star). The mean difference is 1/365.24219 because the Earth needs 365.24219 days for its orbit around the Sun. (see also sidereal day) | + | The time from one upper culmination to the next is approximately 24 hours, and from an upper to a lower culmination is approximately 12 hours. The movement of the [[Earth]] on its [[orbit]] and proper motion of the celestial body affect the time between successive upper culminations of the body. Because of the proper and improper motions of the [[sun]], one solar day (the time between two upper culminations of the sun) is longer than one [https://en.wikipedia.org/wiki/Sidereal_day sidereal day] (the time between two like culminations of any fixed star). The mean difference is 1/365.24219 because the Earth needs 365.24219 days for its orbit around the Sun. (see also sidereal day) |
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| [[Category: Astronomy]] | | [[Category: Astronomy]] |