خط الزوال الرئيسي

الدائرة القطبية

م. السرطان

خط الإستواء

م. الجدي

الدائرة القطبية الجنوبية

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نقاط على خط الزوال 0° شرق

The nations that touch the equator (red) and the prime meridian (blue).

خط الزوال الرئيسي Prime Meridian خط گرينتش Greenwich Meridian هو خط افتراضي لحساب التوقيت سمي بذلك لأنه يمر في مدينة گرينيتش في لندن و يقسم خط غرينتش الكرة الأرضية إلى قسمين شرقي وغربي وهنالك 360 خط طول 180 خط شرقي خط غرينيتش و 180 خط غربي وعلى أساس بعد كل خط يتم حساب الوقت بالزيادة او بالنقصان الزمنى

خَط طول جرينيتش خط يمر من الشمال إلى الجنوب، عبر جرينيتش، وهي ضاحية في لندن، على خريطة الأرض. وغالبًا ما يسمى خط طول جرينيتش باسم خط الزوال الأول، ويُصّنف بخط الطول صفر، ولكن خطوط الطول الأخرى مرقَّمة شرقيّْ وغربيّ هذا الخط. انظر: خط الطول. وخط طول جرينيتش، أيضًا، نقطة بداية المناطق الزمنية (الوقتية) العالمية. وهناك 24 منطقة زمنية، كل منها بعرض خط طول 15°م. ويقع خط طول جرينيتش في وسط منطقة زمنية. وبالانتقال شرقًا من جرينيتش، يصبح الوقت متأخرًا ساعة بالدخول إلى كل منطقة زمنية. وبالانتقال إلى الغرب، يصبح الوقت مبكرًا ساعة في كل منطقة زمنية. انظر: الوقت. وفي عام 1884م، قرر مؤتمر دولي أن يكون خط الطول الذي يمر عبر المرصد الملكي في بريطانيا خط الطول الرئيسي للعالم. وأدى المرصد دوراً أساسيًا في الملاحة البحرية في تلك الأيام، وفي تطوير وسائل ضبط الوقت اللازمة للملاحة. وفي أواسط القرن العشرين، تم نقل مرصد جرينيتش الملكي من جرينيتش إلى قلعة هيرستمونسوكس في سَسكْس لتفادي التشويش الناجم عن أضواء لندن. ثم نقل المرصد إلى كمبردج في عام 1990م وتم إغلاقه في عام 1998م. بيد أن موقع جرينيتش الأصلي ما زال هو خط الطول الرئيسي.

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 التاريخ

انظر أيضاً: تاريخ خط الطول

Ptolemy's 1st projection, redrawn under Maximus Planudes around 1300, using a prime meridian through the Canary Islands west of Africa, at the left-hand edge of the map. (The obvious central line shown here is the junction of two sheets).

The notion of longitude for Greeks was developed by the Greek Eratosthenes (c. 276 – 195 BCE) in Alexandria, and Hipparchus (c. 190 – 120 BCE) in Rhodes, and applied to a large number of cities by the geographer Strabo (64/63 BCE – c. 24 CE). But it was Ptolemy (c. 90 – 168 CE) who first used a consistent meridian for a world map in his Geographia.

Ptolemy used as his basis the "Fortunate Isles", a group of islands in the Atlantic, which are usually associated with the Canary Islands (13° to 18°W), although his maps correspond more closely to the Cape Verde islands (22° to 25° W). The main point is to be comfortably west of the western tip of Africa (17.5° W) as negative numbers were not yet in use. His prime meridian corresponds to 18° 40' west of Winchester (about 20°W) today. At that time the chief method of determining longitude was by using the reported times of lunar eclipses in different countries.

One of the earliest known descriptions of standard time in India appeared in the 4th century CE astronomical treatise Surya Siddhanta. Postulating a spherical Earth, the book described the thousands years old customs of the prime meridian, or zero longitude, as passing through Avanti, the ancient name for the historic city of Ujjain, and Rohitaka, the ancient name for Rohtak (28°54′N 76°38′E), a city near the Kurukshetra.

William Grigg's facsimile of the 1529 Spanish Padron Real, from the copy made by Diogo Ribeiro and held by the Vatican Library.

Ptolemy's Geographia was first printed with maps at Bologna in 1477, and many early globes in the 16th century followed his lead. But there was still a hope that a "natural" basis for a prime meridian existed. Christopher Columbus reported (1493) that the compass pointed due north somewhere in mid-Atlantic, and this fact was used in the important Treaty of Tordesillas of 1494, which settled the territorial dispute between Spain and Portugal over newly discovered lands. The Tordesillas line was eventually settled at 370 leagues (2,193 kilometers, 1,362 statute miles, or 1,184 nautical miles) west of Cape Verde. This is shown in the copies of Spain's Padron Real made by Diogo Ribeiro in 1527 and 1529. São Miguel Island (25.5°W) in the Azores was still used for the same reason as late as 1594 by Christopher Saxton, although by then it had been shown that the zero magnetic declination line did not follow a line of longitude.

1571 Africa map by Abraham Ortelius, with Cape Verde as its prime meridian.

1682 map of East Asia by Giacomo Cantelli, with Cape Verde as its prime meridian; Japan is thus located around 180° E.

In 1541, Mercator produced his famous 41 cm terrestrial globe and drew his prime meridian precisely through Fuerteventura (14°1'W) in the Canaries. His later maps used the Azores, following the magnetic hypothesis. But by the time that Ortelius produced the first modern atlas in 1570, other islands such as Cape Verde were coming into use. In his atlas longitudes were counted from 0° to 360°, not 180°W to 180°E as is usual today. This practice was followed by navigators well into the 18th century. In 1634, Cardinal Richelieu used the westernmost island of the Canaries, El Hierro, 19° 55' west of Paris, as the choice of meridian. The geographer Delisle decided to round this off to 20°, so that it simply became the meridian of Paris disguised.

خط زوال گرينتش، يمر خلال المرصد الملكي، گرينتش، أسسه السير جورج أيري في 1851. وبحلول عام 1884، أكثر من ثلثي جميع السفن والحمولات استعملته كخط الزوال المرجعي على خرائطهم. وفي أكتوبر من ذلك العام، بطلب من الرئيس الأمريكي تشستر أرثر، اجتمع 41 وفد عن 25 دولة في واشنطن العاصمة، بالولايات المتحدة، في مؤتمر خط الزوال الدولي. وقد اختار هذا المؤتمر خط زوال گرينتش ليصبح خط الزوال الرئيسي الرسمي بسبب شعبيته. إلا أن فرنسا امتنعت عن التصويت واستمرت خرائط فرنسا في استعمال خط زوال پاريس لعدة عقود.

خط زوال گرينتش يميزه في الليل شعاع ليزر ينبعث شمالاً من المرصد الملكي.

In the early 18th century the battle was on to improve the determination of longitude at sea, leading to the development of the marine chronometer by John Harrison. But it was the development of accurate star charts, principally by the first British Astronomer Royal, John Flamsteed between 1680 and 1719 and disseminated by his successor Edmund Halley, that enabled navigators to use the lunar method of determining longitude more accurately using the octant developed by Thomas Godfrey and John Hadley.

In the 18th century most countries in Europe adapted their own prime meridian, usually through their capital, hence in France the Paris meridian was prime, in Prussia it was the Berlin meridian, in Denmark the Copenhagen meridian, and in United Kingdom the Greenwich meridian.

Between 1765 and 1811, Nevil Maskelyne published 49 issues of the Nautical Almanac based on the meridian of the Royal Observatory, Greenwich. "Maskelyne's tables not only made the lunar method practicable, they also made the Greenwich meridian the universal reference point. Even the French translations of the Nautical Almanac retained Maskelyne's calculations from Greenwich – in spite of the fact that every other table in the Connaissance des Temps considered the Paris meridian as the prime."

In 1884, at the International Meridian Conference in Washington, D.C., 22 countries voted to adopt the Greenwich meridian as the prime meridian of the world. The French argued for a neutral line, mentioning the Azores and the Bering Strait, but eventually abstained and continued to use the Paris meridian until 1911.

The current international standard Prime Meridian is the IERS Reference Meridian. The International Hydrographic Organization adopted an early version of the IRM in 1983 for all nautical charts. It was adopted for air navigation by the International Civil Aviation Organization on 3 March 1989.

 خط الزوال الرئيسي الدولي

Since 1984, the international standard for the Earth's prime meridian is the IERS Reference Meridian. Between 1884 and 1984, the meridian of Greenwich was the world standard. These meridians are very close to each other.

 خط الزوال الرئيسي في جرينتش

The line of the Greenwich meridian at the Royal Observatory, Greenwich

المقالة الرئيسية: Prime meridian (Greenwich)

In October 1884 the Greenwich Meridian was selected by delegates (forty-one delegates representing twenty-five nations) to the International Meridian Conference held in Washington, D.C., United States to be the common zero of longitude and standard of time reckoning throughout the world.

The position of the historic prime meridian, based at the Royal Observatory, Greenwich, was established by Sir George Airy in 1851. It was defined by the location of the Airy Transit Circle ever since the first observation he took with it. Prior to that, it was defined by a succession of earlier transit instruments, the first of which was acquired by the second Astronomer Royal, Edmond Halley in 1721. It was set up in the extreme north-west corner of the Observatory between Flamsteed House and the Western Summer House. This spot, now subsumed into Flamsteed House, is roughly 43 metres (47 yards) to the west of the Airy Transit Circle, a distance equivalent to roughly 2 seconds of longitude. It was Airy's transit circle that was adopted in principle (with French delegates, who pressed for adoption of the Paris meridian abstaining) as the Prime Meridian of the world at the 1884 International Meridian Conference.

All of these Greenwich meridians were located via an astronomic observation from the surface of the Earth, oriented via a plumb line along the direction of gravity at the surface. This astronomic Greenwich meridian was disseminated around the world, first via the lunar distance method, then by chronometers carried on ships, then via telegraph lines carried by submarine communications cables, then via radio time signals. One remote longitude ultimately based on the Greenwich meridian using these methods was that of the North American Datum 1927 or NAD27, an ellipsoid whose surface best matches mean sea level under the United States.

 IERS Reference Meridian

المقالة الرئيسية: IERS Reference Meridian

Beginning in 1973 the International Time Bureau and later the International Earth Rotation and Reference Systems Service changed from reliance on optical instruments like the Airy Transit Circle to techniques such as lunar laser ranging, satellite laser ranging, and very-long-baseline interferometry. The new techniques resulted in the IERS Reference Meridian, the plane of which passes through the centre of mass of the Earth. This differs from the plane established by the Airy transit, which is affected by vertical deflection (the local vertical is affected by influences such as nearby mountains). The change from relying on the local vertical to using a meridian based on the centre of the Earth caused the modern prime meridian to be 5.3″ east of the astronomic Greenwich prime meridian through the Airy Transit Circle. At the latitude of Greenwich, this amounts to 102 metres (112 yards). This was officially accepted by the Bureau International de l'Heure (BIH) in 1984 via its BTS84 (BIH Terrestrial System) that later became WGS84 (World Geodetic System 1984) and the various International Terrestrial Reference Frames (ITRFs).

Due to the movement of Earth's tectonic plates, the line of 0° longitude along the surface of the Earth has slowly moved toward the west from this shifted position by a few centimetres (inches); that is, towards the Airy Transit Circle (or the Airy Transit Circle has moved toward the east, depending on your point of view) since 1984 (or the 1960s). With the introduction of satellite technology, it became possible to create a more accurate and detailed global map. With these advances there also arose the necessity to define a reference meridian that, whilst being derived from the Airy Transit Circle, would also take into account the effects of plate movement and variations in the way that the Earth was spinning. As a result, the IERS Reference Meridian was established and is commonly used to denote the Earth's prime meridian (0° longitude) by the International Earth Rotation and Reference Systems Service, which defines and maintains the link between longitude and time. Based on observations to satellites and celestial compact radio sources (quasars) from various coordinated stations around the globe, Airy's transit circle drifts northeast about 2.5 centimetres (1 inch) per year relative to this Earth-centred 0° longitude.

It is also the reference meridian of the Global Positioning System operated by the United States Department of Defense, and of WGS84 and its two formal versions, the ideal International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF). A current convention on the Earth uses the line of longitude 180° opposite the IRM as the basis for the International Date Line.

 قائمة الأماكن

بدءاً من القطب الشمالي متجهاً جنوباً إلى القطب الجنوبي، يمر خط الزوال الرئيسي (في عام 2016) عبر ثمان بلدان وأربع بحار وثلاث محيطات وقنال واحد:

The prime meridian on a globe

The prime meridian sign in Parnay, Maine-et-Loire, France.

Prime meridian sign near Somanya, Ghana.

الإحداثيات (التقريبية)	البلد، المنطقة أو البحر	ملاحظات
90°0′N 0°0′E	القطب الشمالي والمحيط المتجمد الشمالي
85°46′N 0°0′E	المنطقة الاقتصادية الخالصة (EEZ) لجرينلاند (Denmark)
81°39′N 0°0′E	بحر گرينلاند
80°29′N 0°0′E	EEZ of Svalbard (Norway)
76°11′N 0°0′E	International waters
73°44′N 0°0′E	EEZ of يان ماين (النرويج)
72°53′N 0°0′E	البحر النرويجي
69°7′N 0°0′E	المياه الدولية
64°42′N 0°0′E	EEZ of النرويج
63°29′N 0°0′E	EEZ of بريطانيا العظمى
61°0′N 0°0′E	North Sea
53°46′N 0°0′E	المملكة المتحدة	From Tunstall in East Riding to Peacehaven, passing through Greenwich
50°47′N 0°0′E	English Channel	EEZ of Great Britain
50°14′N 0°0′E	English Channel	EEZ of France
49°20′N 0°0′E	فرنسا	From Villers-sur-Mer to Gavarnie
42°41′N 0°0′E	إسپانيا	From Cilindro de Marboré to Castellón de la Plana
39°56′N 0°0′E	Mediterranean Sea	Gulf of Valencia; EEZ of Spain
38°52′N 0°0′E	إسپانيا	From El Verger to Calp
38°38′N 0°0′E	البحر المتوسط	EEZ of Spain
37°1′N 0°0′E	البحر المتوسط	EEZ of Algeria
35°50′N 0°0′E	الجزائر	From Stidia to Algeria-Mali border near برج باجي مختار
21°52′N 0°0′E	مالي	Passing through Gao
15°00′N 0°0′E	بوركينا فاسو	For about 432 km, running through Cinkassé.
11°7′N 0°0′E	توگو	For about 3.4 km
11°6′N 0°0′E	غانا	For about 16 km
10°58′N 0°0′E	توگو	For about 39 km
10°37′N 0°0′E	غانا	From the Togo-Ghana border near Bunkpurugu to Tema Passing through Lake Volta at 7°46′N 0°0′E
5°37′N 0°0′E	Atlantic Ocean	EEZ of غانا
1°58′N 0°0′E		International waters
0°0′N 0°0′E		Passing through the Equator (see Null Island)
51°43′S 0°0′E		EEZ of جزيرة بوڤيه (النرويج)
57°13′S 0°0′E		المياه الدولية
60°0′S 0°0′E	المحيط الجنوبي	المياه الدولية
69°36′S 0°0′E	أنتارتيكا	أرض الملكة مود، claimed by نرويج
90°0′S 0°0′E	أنتارتيكا	Amundsen–Scott South Pole Station، القطب الجنوبي

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 خطوط الزوال الرئيسية على الأجرام السماوية الأخرى

انظر أيضاً: خط طول (كواكب)

"Prime meridian (planets)" redirects here. It is not to be confused with Central meridian (planets).

As on the Earth, prime meridians must be arbitrarily defined. Often a landmark such as a crater is used; other times a prime meridian is defined by reference to another celestial object, or by magnetic fields. The prime meridians of the following planetographic systems have been defined:

• Two different heliographic coordinate systems are used on the Sun. The first is the Carrington heliographic coordinate system. In this system, the prime meridian passes through the center of the solar disk as seen from the Earth on 9 November 1853, which is when the English astronomer Richard Christopher Carrington started his observations of sunspots. The second is the Stonyhurst heliographic coordinates system, originated at Stonyhurst Observatory in Lancashire, England.
• In 1975 the prime meridian of Mercury was defined to be 20° east of the crater Hun Kal. This meridian was chosen because it runs through the point on Mercury's equator where the average temperature is highest (due to the planet's rotation and orbit, the sun briefly retrogrades at noon at this point during perihelion, giving it more sunlight).
• Defined in 1992, the prime meridian of Venus passes through the central peak in the crater Ariadne, chosen arbitrarily.
• The prime meridian of the Moon lies directly in the middle of the face of the Moon visible from Earth and passes near the crater Bruce.
• The prime meridian of Mars was established in 1971 and passes through the center of the crater Airy-0, although it is fixed by the longitude of the Viking 1 lander, which is defined to be 47.95137°W.
• The prime meridian on Ceres runs through the Kait crater, which was arbitrarily chosen because it is near the equator (about 2° south).
• The prime meridian on 4 Vesta is 4 degrees east of the crater Claudia, chosen because it is sharply defined.
• Jupiter has several coordinate systems because its cloud tops—the only part of the planet visible from space—rotate at different rates depending on latitude. It is unknown whether Jupiter has any internal solid surface that would enable a more Earth-like coordinate system. System I and System II coordinates are based on atmospheric rotation, and System III coordinates use Jupiter's magnetic field. The prime meridians of Jupiter's four Galilean moons were established in 1979.
  • Europa's prime meridian is defined such that the crater Cilix is at 178° E.^{[بحاجة لمصدر]} The 0° longitude runs through the middle of the face that is always turned towards Jupiter.
  • Io's prime meridian, like that of Earth's moon, is defined so that it runs through the middle of the face that is always turned towards Jupiter (the near side, known as the subjovian hemisphere).
  • Ganymede's prime meridian is defined such that the crater Anat is at 128° W, and the 0° longitude runs through the middle of the subjovian hemisphere.
  • Callisto's prime meridian is defined such that the crater Saga is at 34° E.
• Titan is the largest moon of Saturn and, like the Earth's moon, always has the same face towards Saturn, and so the middle of that face is 0 longitude.
• Like Jupiter, Neptune is a gas giant, so any surface is obscured by clouds. The prime meridian of its largest moon, Triton, was established in 1991.
• Pluto's prime meridian is defined as the meridian passing through the center of the face that is always towards Charon, its largest moon, as the two are tidally locked to each other. Charon's prime meridian is similarly defined as the meridian always facing directly toward Pluto.

 قائمة خطوط الزوال الرئيسية على الأرض

Locality	Modern longitude	Meridian name	Image	Comment
Bering Strait	168°30′ W		168° class=notpageimage| خط الطول 168 غرب	Offered in 1884 as possibility for a neutral prime meridian by Pierre Janssen at the International Meridian Conference
Washington, D.C.	77°03′56.07″ W (1897) or 77°04′02.24″ W (NAD 27) or 77°04′01.16″ W (NAD 83)	New Naval Observatory meridian	77° class=notpageimage| خط الطول 77 غرب
	77°02′48.0″ W, 77°03′02.3″, 77°03′06.119″ W or 77°03′06.276″ W (both presumably NAD 27). If NAD27, the latter would be 77°03′05.194″ W (NAD 83)	Old Naval Observatory meridian
	77°02′11.56299″ W (NAD 83), 77°02′11.55811″ W (NAD 83), 77°02′11.58325″ W (NAD 83) (three different monuments originally intended to be on the White House meridian)	White House meridian
	77°00′32.6″ W (NAD 83)	Capitol meridian
Philadelphia	75° 10′ 12″ W		75° class=notpageimage| خط الطول 75 غرب
Rio de Janeiro	43° 10′ 19″ W		43° class=notpageimage| خط الطول 43rd غرب
Fortunate Isles / Azores	25° 40′ 32″ W		25° class=notpageimage| خط الطول 25 غرب	Used until the Middle Ages, proposed as one possible neutral meridian by Pierre Janssen at the International Meridian Conference
El Hierro (Ferro), Canary Islands	18° 03′ W, later redefined as 17° 39′ 46″ W	Ferro meridian	18° class=notpageimage| خط الطول 18 غرب
Tenerife	16°38′22″ W	Tenerife meridian	16° class=notpageimage| خط الطول 16 غرب	Rose to prominence with Dutch cartographers and navigators after they abandoned the idea of a magnetic meridian
Lisbon	9° 07′ 54.862″ W		9° class=notpageimage| خط الطول 9 غرب
Cadiz	6° 17′ 35.4" W	Cadiz meridian	6° class=notpageimage| خط الطول 6 غرب	Royal Observatory in southeast tower of Castillo de la Villa, used 1735–1850 by Spanish Navy.
Madrid	3° 41′ 16.58″ W		3° class=notpageimage| خط الطول 3rd غرب
Kew	0° 00′ 19.0″ W	Prime Meridian (prior to Greenwich)	0° class=notpageimage| خط گرينتش	Located at King George III's Kew Observatory
Greenwich	0° 00′ 05.33″ W	United Kingdom Ordnance Survey Zero Meridian		Bradley Meridian
	0° 00′ 05.3101″ W	Greenwich meridian		Airy Meridian
	0° 00′ 00.00″	IERS Reference Meridian
Paris	2° 20′ 14.025″ E	Paris meridian	2° class=notpageimage| خط الطول 2nd شرق
Brussels	4° 22′ 4.71″ E		4° class=notpageimage| خط الطول 4 شرق
Antwerp	4° 24′ E	Antwerp meridian
Amsterdam	4° 53′ E			Through the Westerkerk in Amsterdam; used to define the legal time in the Netherlands from 1909 to 1937
Pisa	10° 24′ E		10° class=notpageimage| خط الطول 10 شرق
Oslo (Kristiania)	10° 43′ 22.5″ E
Florence	11°15′ E	Florence meridian	11° class=notpageimage| خط الطول 11 شرق	Used in the Peters projection, 180° from a meridian running through the Bering Strait
Rome	12° 27′ 08.4″ E	Meridian of Monte Mario	12° class=notpageimage| خط الطول 12 شرق	Used in Roma 40 Datum
Copenhagen	12° 34′ 32.25″ E			Rundetårn
Naples	14° 15′ E		14° class=notpageimage| خط الطول 14 شرق
Pressburg	17° 06′ 03″ E	Meridianus Posoniensis	17° class=notpageimage| خط الطول 17 شرق	Used by Sámuel Mikoviny
Stockholm	18° 03′ 29.8″ E		18° class=notpageimage| خط الطول 18 شرق	At the Stockholm Observatory
Buda	19° 03′ 37″ E	Meridianu(s) Budense	19° class=notpageimage| خط الطول 19 شرق	Used between 1469 and 1495; introduced by Regiomontanus, used by Marcin Bylica, Galeotto Marzio, Miklós Erdélyi (1423–1473), Johannes Tolhopff (c. 1445–1503), Johannes Muntz. Set in the royal castle (and observatory) of Buda.
Kraków	19° 57′ 21.43″ E	Kraków meridian		at the Old Kraków Observatory at the Śniadecki' College; mentioned also in Nicolaus Copernicus's work On the Revolutions of the Heavenly Spheres.
Warsaw	21° 00′ 42″ E	Warsaw meridian	21° class=notpageimage| خط الطول 21st شرق
Várad	21° 55′ 16″ E	Tabulae Varadienses	21° class=notpageimage| خط الطول 21st شرق	Between 1464 and 1667, a prime meridian was set in the Fortress of Oradea (Varadinum at the time) by Georg von Peuerbach. In his logbook Columbus stated, he had one copy of Tabulae Varadienses (Tabula Varadiensis or Tabulae directionum) on board to calculate the actual meridian based on the position of the Moon, in correlation to Várad. Amerigo Vespucci also recalled, how was he acquired the knowledge to calculate meridians by means of these tables.
Alexandria	29° 53′ E	Meridian of Alexandria	29° class=notpageimage| خط الطول 29 شرق	The meridian of Ptolemy's Almagest.
Saint Petersburg	30° 19′ 42.09″ E	Pulkovo meridian	30° class=notpageimage| خط الطول 30 شرق
Great Pyramid of Giza	31° 08′ 03.69″ E		31° class=notpageimage| خط الطول 31st شرق	1884
Jerusalem	35° 13′ 47.1″ E		35° class=notpageimage| خط الطول 35 شرق
Mecca	39° 49′ 34″ E		39° class=notpageimage| خط الطول 39 شرق	See also Mecca Time
	Approx. 59° E		59° class=notpageimage| خط الطول 59 شرق	Maimonides calls this point אמצע היישוב, "the middle of the habitation", i.e. the habitable hemisphere. Evidently this was a convention accepted by Arab geographers of his day.
Ujjain	75° 47′ E		75° class=notpageimage| خط الطول 75 شرق	Used from 4th century CE Indian astronomy and calendars(see also Time in India).
Kyoto	136° 14′ E		136° class=notpageimage| خط الطول 136 شرق	Used in 18th and 19th (officially 1779–1871) century Japanese maps. Exact place unknown, but in "Kairekisyo" in Nishigekkoutyou-town in Kyoto, then the capital.
	~ 180		180° class=notpageimage| خط الطول 180	Opposite of Greenwich, proposed 13 October 1884 on the International Meridian Conference by Sandford Fleming

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 انظر أيضاً

• 1st meridian east
• 1st meridian west
• 180th meridian
• Null Island
• Geographical center of Earth

 وصلات خارجية

• The prime meridian line at the The Royal Observatory in Greenwich
• International Conference Held at Washington for the Purpose of Fixing a Prime Meridian, available at Project Gutenberg.
• scanned TIFFs of the conference proceedings
• Prime meridians in use in the 1880s, by country
• Canadian Prime Meridian