Garis bujur: Perbedaan antara revisi

[[ImageBerkas:WorldMapLongLat-eq-circles-tropics-non.png|thumbjmpl|450px300px|[[Peta]] Bumi, memperlihatkan garis-garis bujur, yang nampaktampak melengkung dan [[vertikal]] pada proyeksi ini, namun sebenarnya garis-garis bujur tersebut merupakan setengah dari sebuah [[lingkaran besar]] bumi.]]

'''Garis Bujur''' kadangkala([[Lambda|λ]]), dinotasikanadalah olehsuatu garis khayal yang ditarik dari ujung [[LambdaKutub Utara|abjadkutub Yunaniutara]] &lambda;sampai ke [[Kutub Selatan|kutub selatan]], yang digunakan untuk menentukan lokasi di bumi pada [[globe]] atau [[peta]].<ref name=":0">{{Cite web|title=Garis Bujur dan Garis Lintang|url=https://www.erlangga.co.id/materi-belajar/smp/8895-garis-bujur-dan-garis-lintang.html|website=www.erlangga.co.id|access-date=2020-12-24|archive-date=2022-08-11|archive-url=https://web.archive.org/web/20220811234718/https://www.erlangga.co.id/materi-belajar/smp/8895-garis-bujur-dan-garis-lintang.html|dead-url=no}}</ref> Garis bujur menggambarkan lokasi sebuah tempat di [[timur]] atau [[barat]] [[Bumi]] dari sebuah garis utara-selatan yang disebut [[Meridian Utama]]. LongitudeGaris diberikanBujur dihitung berdasarkan [[sudut|pengukuran sudut]] yang berkisar dari 0° di Meridian Utama ke +180° arah timur dan &minus;180−180° arah barat. Tidak seperti [[lintang]] yang memiliki [[ekuator]] sebagiasebagai posisi awal alami, tidak ada posisi awal alami untuk bujur. Oleh karena itu, sebuah dasargaris [[meridian]] harus dipilih. Meskipun [[kartografer]] [[Britania Raya]] telah lama menggunakan meridian [[Observatorium Greenwich]] di [[London]], referensi lainnya digunakan di tempat yang berbeda, termasuk [[Ferro]], [[Roma]], [[Kopenhagen]], [[Yerusalem]], [[Saint Petersburg]], [[Pisa]], [[Paris]], [[Philadelphia, Pennsylvania|Philadelphia]], dan [[Washington, D.C.]]. Pada [[1884]], [[Meridian Utama|Konferensi Meridian Internasional]] mengadopsi meridian Greenwich sebagai '''Meridian utama universal''' atau ''titik nol bujur''.

Each degree of longitude is further sub-divided into 60 [[minute of arc|minutes]], each of which divided into 60 seconds. A longitude is thus specified as '''23&deg;°&nbsp;27&prime;27′&nbsp;30&quot;"&nbsp;E'''. For high accuracy, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed as a decimal fraction, thus: '''23&deg;°&nbsp;27.500&prime;500′&nbsp;E'''. Degrees expressed as a decimal number is also used: '''23.45833&deg;°&nbsp;E'''. Sometimes, the West/East suffix is replaced by a negative sign for West. Confusingly, the convention of negative for East is also sometimes seen. The preferred convention that East is positive is consistent with the right-handed ''x''-axis in the [[Cartesian coordinate system]].

Longitude at a point may be determined by calculating the time difference between that at its location and [[Coordinated Universal Time]] (UTC). Since there are 24 hours in a day and 360 degrees in a circle, the sun moves 15 degrees per hour (360°/24 hours = 15° per hour). So if the [[time zone]] a person is in is three hours ahead of UTC then that person is near 45° longitude (3 hours &times;× 15° per hour = 45°). The word ''near'' was used because the point might not be at the center of the time zone; also the time zones are defined politically, so their centers and boundaries often do not lie on [[meridian (astronomy)|meridians]] at multiples of 15°. In order to perform this calculation, however, a person needs to have a [[chronometer]] (watch) set to UTC and needs to determine local time by solar observation or astronomical observation. The details are more complex than described here: see the articles on [[Universal Time]] and on the [[Equation of time]] for more details.

== Lihat jugapula ==

* [[navigasiGaris langitlintang]]

* [[dead reckoningKhatulistiwa]]

* [[sistemSistem koordinat geografi]]

* [[navigasiKomet]]

* [http://www.bcca.org/misc/qiblih/latlong.html Look-up Latitude and Longitude] {{Webarchive|url=https://web.archive.org/web/20041218045253/http://www.bcca.org/misc/qiblih/latlong.html |date=2004-12-18 }}

* [http://jan.ucc.nau.edu/~cvm/latlon_find_location.html Resources for determining your latitude and longitude] {{Webarchive|url=https://web.archive.org/web/20080519082322/http://jan.ucc.nau.edu/~cvm/latlon_find_location.html |date=2008-05-19 }}

* [http://www.pbs.org/wgbh/nova/longitude/ PBS Nova Online: ''Lost at Sea, the Search for Longitude''] {{Webarchive|url=https://web.archive.org/web/20221006111953/https://www.pbs.org/wgbh/nova/longitude/ |date=2022-10-06 }}

* [http://www.hnsky.org/iau-iag.htm IAU/IAG Working Group On Cartographic Coordinates and Rotational Elements of the Planets and Satellites]{{Webarchive|url=https://web.archive.org/web/20181031190003/http://www.hnsky.org/iau-iag.htm |date=2018-10-31 }}