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Prime meridian

A prime meridian is an arbitrarily-chosen meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian (the 180th meridian in a 360°-system) form a great circle. This great circle divides a spheroid, like Earth, into two hemispheres: the Eastern Hemisphere and the Western Hemisphere (for an east-west notational system). For Earth's prime meridian, various conventions have been used or advocated in different regions throughout history.[1] Earth's current international standard prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard.[2]

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Modern IERS Reference Meridian on Earth

Gerardus Mercator in his Atlas Cosmographicae (1595) used a prime meridian somewhere close to 25°W, passing just to the west of Santa Maria Island in the Azores in the Atlantic Ocean. His 180th meridian runs along the Strait of Anián (Bering Strait)

A prime meridian for a planetary body not tidally locked (or at least not in synchronous rotation) is entirely arbitrary, unlike an equator, which is determined by the axis of rotation. However, for celestial objects that are tidally locked (more specifically, synchronous), their prime meridians are determined by the face always inward of the orbit (a planet facing its star, or a moon facing its planet), just as equators are determined by rotation.

Longitudes for the Earth and Moon are measured from their prime meridian (at 0°) to 180° east and west. For all other Solar System bodies, longitude is measured from 0° (their prime meridian) to 360°. West longitudes are used if the rotation of the body is prograde (or 'direct', like Earth), meaning that its direction of rotation is the same as that of its orbit. East longitudes are used if the rotation is retrograde.[3]

History edit

 
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.[1] 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 / 28.900°N 76.633°E / 28.900; 76.633 (Rohitaka (Rohtak))), a city near the Kurukshetra.[4][better source needed]

 
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.[a] 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 deviation line did not follow a line of longitude.[8]

 
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.[9] 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.[10]

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.[11]

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 Germany 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."[12]

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.[13] 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.[14] It was adopted for air navigation by the International Civil Aviation Organization on 3 March 1989.[15]

International prime meridian edit

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 physically very close to each other.

Prime meridian at Greenwich edit

 
The line of the Greenwich meridian at the Royal Observatory, 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.[16][b]

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.[18] 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 to the west of the Airy Transit Circle, a distance equivalent to roughly 2 seconds of longitude.[19] 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.[20][21]

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 edit

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.[22] 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; 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.[23] 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 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).[24][25][c] A current convention on the Earth uses the line of longitude 180° opposite the IRM as the basis for the International Date Line.

List of places edit

On Earth, starting at the North Pole and heading south to the South Pole, the IERS Reference Meridian (as of 2016) passes through:

Co-ordinates
(approximate)
Country, territory or sea Notes
90°0′N 0°0′E / 90.000°N 0.000°E / 90.000; 0.000 (North Pole) Arctic Ocean
85°46′N 0°0′E / 85.767°N 0.000°E / 85.767; 0.000 (EEZ of Greenland (Denmark)) Exclusive Economic Zone (EEZ) of Greenland (Denmark)
81°39′N 0°0′E / 81.650°N 0.000°E / 81.650; 0.000 (Greenland Sea) Greenland Sea
80°29′N 0°0′E / 80.483°N 0.000°E / 80.483; 0.000 (EEZ of Svalbard (Norway)) EEZ of Svalbard (Norway)
76°11′N 0°0′E / 76.183°N 0.000°E / 76.183; 0.000 (International waters) International waters
73°44′N 0°0′E / 73.733°N 0.000°E / 73.733; 0.000 (EEZ of Jan Mayen) EEZ of Jan Mayen (Norway)
72°53′N 0°0′E / 72.883°N 0.000°E / 72.883; 0.000 (Norwegian Sea) Norwegian Sea
69°7′N 0°0′E / 69.117°N 0.000°E / 69.117; 0.000 (International waters) International waters
64°42′N 0°0′E / 64.700°N 0.000°E / 64.700; 0.000 (EEZ of Norway) EEZ of Norway
63°29′N 0°0′E / 63.483°N 0.000°E / 63.483; 0.000 (EEZ of Great Britain) EEZ of Great Britain
61°0′N 0°0′E / 61.000°N 0.000°E / 61.000; 0.000 (North Sea) North Sea
53°46′N 0°0′E / 53.767°N 0.000°E / 53.767; 0.000 (United Kingdom)   United Kingdom From Tunstall in East Riding to Peacehaven, passing through Greenwich
50°47′N 0°0′E / 50.783°N 0.000°E / 50.783; 0.000 (English Channel) English Channel EEZ of Great Britain
50°14′N 0°0′E / 50.233°N 0.000°E / 50.233; 0.000 (EEZ of France) English Channel EEZ of France
49°20′N 0°0′E / 49.333°N 0.000°E / 49.333; 0.000 (France)   France From Villers-sur-Mer to Gavarnie
42°41′N 0°0′E / 42.683°N 0.000°E / 42.683; 0.000 (Spain)   Spain From Cilindro de Marboré to Castellón de la Plana
39°56′N 0°0′E / 39.933°N 0.000°E / 39.933; 0.000 (Mediterranean Sea) Mediterranean Sea Gulf of Valencia; EEZ of Spain
38°52′N 0°0′E / 38.867°N 0.000°E / 38.867; 0.000 (Spain)   Spain From El Verger to Calp
38°38′N 0°0′E / 38.633°N 0.000°E / 38.633; 0.000 (Mediterranean Sea) Mediterranean Sea EEZ of Spain
37°1′N 0°0′E / 37.017°N 0.000°E / 37.017; 0.000 (EEZ of Algeria) Mediterranean Sea EEZ of Algeria
35°50′N 0°0′E / 35.833°N 0.000°E / 35.833; 0.000 (Algeria)   Algeria From Stidia to Algeria-Mali border near Bordj Badji Mokhtar
21°52′N 0°0′E / 21.867°N 0.000°E / 21.867; 0.000 (Mali)   Mali Passing through Gao
15°00′N 0°0′E / 15.000°N 0.000°E / 15.000; 0.000 (Burkina Faso)   Burkina Faso
11°7′N 0°0′E / 11.117°N 0.000°E / 11.117; 0.000 (Togo)   Togo For about 600 m
11°6′N 0°0′E / 11.100°N 0.000°E / 11.100; 0.000 (Ghana)   Ghana For about 16 km
10°58′N 0°0′E / 10.967°N 0.000°E / 10.967; 0.000 (Togo)   Togo For about 39 km
10°37′N 0°0′E / 10.617°N 0.000°E / 10.617; 0.000 (Ghana)   Ghana From the Togo-Ghana border near Bunkpurugu to Tema
Passing through Lake Volta at 7°46′N 0°0′E / 7.767°N 0.000°E / 7.767; 0.000 (Lake Volta)
5°37′N 0°0′E / 5.617°N 0.000°E / 5.617; 0.000 (EEZ of Ghana in Atlantic Ocean) Atlantic Ocean EEZ of Ghana
1°58′N 0°0′E / 1.967°N 0.000°E / 1.967; 0.000 (International waters) International waters
0°0′N 0°0′E / 0.000°N 0.000°E / 0.000; 0.000 (Equator) Passing through the Equator (see Null Island)
51°43′S 0°0′E / 51.717°S 0.000°E / -51.717; 0.000 (EEZ of Bouvet Island) EEZ of Bouvet Island (Norway)
57°13′S 0°0′E / 57.217°S 0.000°E / -57.217; 0.000 (International waters) International waters
60°0′S 0°0′E / 60.000°S 0.000°E / -60.000; 0.000 (Southern Ocean) Southern Ocean International waters
69°36′S 0°0′E / 69.600°S 0.000°E / -69.600; 0.000 (Antarctica) Antarctica Queen Maud Land, claimed by   Norway
90°0′S 0°0′E / 90.000°S 0.000°E / -90.000; 0.000 (Amundsen–Scott South Pole Station) Antarctica Amundsen–Scott South Pole Station, South Pole

Prime meridian on other planetary bodies edit

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.[26] The second is the Stonyhurst heliographic coordinates system, originated at Stonyhurst Observatory in Lancashire, England.
  • In 1975 the prime meridian of Mercury was defined[27][28] to be 20° east of the crater Hun Kal.[29]
  • Defined[30] in 1992, the prime meridian of Venus passes through the central peak in the crater Ariadne.[31]
  • 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[32] 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.[33]
  • 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.[34] 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.[35]
  • 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.[36]
  • 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.

List of historic prime meridians on Earth edit

Locality Modern longitude Meridian name Image Comment
Bering Strait 168°30 W
 
168°
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168th meridian west
Offered in 1884 as possibility for a neutral prime meridian by Pierre Janssen at the International Meridian Conference[37]
Washington, D.C. 77°0356.07″ W (1897) or 77°0402.24″ W (NAD 27)[clarification needed] or 77°0401.16″ W (NAD 83) New Naval Observatory meridian
 
77°
class=notpageimage|
77th meridian west
77°0248.0″ W, 77°0302.3″, 77°0306.119″ W or 77°0306.276″ W (both presumably NAD 27). If NAD27, the latter would be 77°0305.194″ W (NAD 83) Old Naval Observatory meridian
77°0211.56299″ W (NAD 83),[38] 77°0211.55811″ W (NAD 83),[39] 77°0211.58325″ W (NAD 83)[40] (three different monuments originally intended to be on the White House meridian) White House meridian
77°0032.6″ W (NAD 83) Capitol meridian
Philadelphia 75° 10 12″ W
 
75°
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75th meridian west
[41][42]
Rio de Janeiro 43° 10 19″ W
 
43°
class=notpageimage|
43rd meridian west
[43]
Fortunate Isles / Azores 25° 40 32″ W
 
25°
class=notpageimage|
25th meridian west
Used until the Middle Ages, proposed as one possible neutral meridian by Pierre Janssen at the International Meridian Conference[44]
El Hierro (Ferro),
Canary Islands
18° 03 W,
later redefined as
17° 39 46″ W
Ferro meridian
 
18°
class=notpageimage|
18th meridian west
[45]
Tenerife 16°3822″ W Tenerife meridian
 
16°
class=notpageimage|
16th meridian west
Rose to prominence with Dutch cartographers and navigators after they abandoned the idea of a magnetic meridian[46]
Lisbon 9° 07 54.862″ W
 
class=notpageimage|
9th meridian west
[47]
Cadiz 6° 17 35.4" W Cadiz meridian
 
class=notpageimage|
6th meridian west
Royal Observatory in southeast tower of Castillo de la Villa, used 1735–1850 by Spanish Navy.[48][49]
Madrid 3° 41 16.58″ W
 
class=notpageimage|
3rd meridian west
[47]
Kew 0° 00 19.0″ W Prime Meridian (prior to Greenwich)
 
class=notpageimage|
Prime meridian
Located at King George III's Kew Observatory
Greenwich 0° 00 05.33″ W United Kingdom Ordnance Survey Zero Meridian Bradley Meridian[19]
0° 00 05.3101″ W Greenwich meridian Airy Meridian[19]
0° 00 00.00″ IERS Reference Meridian
Paris 2° 20 14.025″ E Paris meridian
 
class=notpageimage|
2nd meridian east
Brussels 4° 22 4.71″ E
 
class=notpageimage|
4th meridian east
[47]
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[50]
Pisa 10° 24 E
 
10°
class=notpageimage|
10th meridian east
[41]
Oslo (Kristiania) 10° 43 22.5″ E [41][42]
Florence 11°15 E Florence meridian
 
11°
class=notpageimage|
11th meridian east
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|
12th meridian east
Used in Roma 40 Datum[51]
Copenhagen 12° 34 32.25″ E Rundetårn[52]
Naples 14° 15 E
 
14°
class=notpageimage|
14th meridian east
[44]
Pressburg 17° 06 03″ E Meridianus Posoniensis
 
17°
class=notpageimage|
17th meridian east
Used by Sámuel Mikoviny
Stockholm 18° 03 29.8″ E
 
18°
class=notpageimage|
18th meridian east
At the Stockholm Observatory[47]
Buda 19° 03 37″ E Meridianu(s) Budense
 
19°
class=notpageimage|
19th meridian east
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.[d]
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|
21st meridian east
[47]
Várad 21° 55 16″ E Tabulae Varadienses
 
21°
class=notpageimage|
21st meridian east
[56] Between 1464 and 1667, a prime meridian was set in the Fortress of Oradea (Varadinum at the time) by Georg von Peuerbach.[57] 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.[58]
Alexandria 29° 53 E Meridian of Alexandria
 
29°
class=notpageimage|
29th meridian east
The meridian of Ptolemy's Almagest.
Saint Petersburg 30° 19 42.09″ E Pulkovo meridian
 
30°
class=notpageimage|
30th meridian east
Great Pyramid of Giza 31° 08 03.69″ E
 
31°
class=notpageimage|
31st meridian east
1884[59]
Jerusalem 35° 13 47.1″ E
 
35°
class=notpageimage|
35th meridian east
[42]
Mecca 39° 49 34″ E
 
39°
class=notpageimage|
39th meridian east
See also Mecca Time
Approx. 59° E
 
59°
class=notpageimage|
59th meridian east
Maimonides[60] 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|
75th meridian east
Used from 4th century CE Indian astronomy and calendars(see also Time in India).[61]
Kyoto 136° 14 E
 
136°
class=notpageimage|
136th meridian east
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.[citation needed]
~ 180
 
180°
class=notpageimage|
180th meridian
Opposite of Greenwich, proposed 13 October 1884 on the International Meridian Conference by Sandford Fleming[44]

See also edit

Notes edit

  1. ^ These figures use the legua náutica (nautical league) of four Roman miles totalling 5.926 km (3.682 mi), which was used by Spain during the 15th, 16th, and 17th centuries for navigation.[5] In 1897 Henry Harrise noted that Jaime Ferrer, the expert consulted by King Ferdinand and Queen Isabella, stated that a league was four miles of six stades each.[6] Modern scholars agree that the geographic stade was the Roman or Italian stade, not any of several other Greek stades, supporting these figures.[7] Harrise is in the minority when he uses the stade of 192.27 m (630.8 ft) marked within the stadium at Olympia, Greece, resulting in a league (32 stades) of 6.153 km (3.823 mi), 3.8% larger.
  2. ^ Voting took place on 13 October and the resolutions were adopted on 22 October 1884.[17] The modern prime meridian, the IERS Reference Meridian, is placed very near this meridian.[13]
  3. ^ The astronomic latitude of the Royal Observatory is 51°2838″N whereas its latitude on the European Terrestrial Reference Frame (1989) datum is 51°2840.1247″N.
  4. ^ When Tolhopff handed over his book, titled Stellarium (1480),[53] to King Matthias Corvinus, he emphasized that he had used the meridian of Buda for his calculations. The German physician, Johannes Müntz used it the same way in his 1495 calendar. However, in the second edition, he used the Vienna meridian.[54][55]

References edit

  1. ^ a b Norgate & Norgate 2006.
  2. ^ "What is the Prime Meridian and why is it in Greenwich?". Royal Museums Greeenwich. from the original on 13 December 2021. Retrieved 13 December 2021. The IRM is the only meridian that may now be described as the prime meridian of the world, as it defines 0° longitude by international agreement. The IRM passes 102.5 metres to the east of the historic Prime Meridian of the World at the latitude of the Airy Transit Circle here. The entire Observatory and the historic Prime Meridian now lie to the west of the true prime meridian.
  3. ^ Archimal, B. A. (2015), Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015 (PDF), p. 27 of 46, (PDF) from the original on 6 August 2019, retrieved 6 August 2019, The range of longitudes shall extend from 0° to 360°. Thus, west longitudes are used when the rotation is direct, and east longitudes are used when the rotation is retrograde. ... The Earth, Sun, and Moon do not traditionally follow this definition. Their rotations are direct and longitudes run both east and west 180°, or positive to the east 360°.
  4. ^ Schmidt, Olaf H. (1944). "The Computation of the Length of Daylight in Hindu Astronomy". Isis. The University of Chicago Press. 35 (3): 205–211. doi:10.1086/358709. JSTOR 330729. S2CID 145178197. from the original on 26 January 2022.
  5. ^ Chardon, Roland (1980). "The linear league in North America". Annals of the Association of American Geographers. 70 (2): 129–153 [pp. 142, 144, 151]. doi:10.1111/j.1467-8306.1980.tb01304.x. JSTOR 2562946.
  6. ^ Harrisse, Henry (1897). The Diplomatic History of America: Its first chapter 1452—1493—1494. London: Stevens. pp. 85–97, 176–190. ISBN 9780697000071. OCLC 1101220811.
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Works cited edit

  • Burgess, Ebenezer (1860), "Translation of the Surya-Siddhanta", Journal of the American Oriental Society (e-book), vol. 6 (published 2013), p. 185
  • Dolan, Graham (2013a). "The Greenwich Meridian before the Airy Transit Circle". The Greenwich Meridian. from the original on 2 May 2012. Retrieved 6 January 2013.
  • Dolan, Graham (2013b). "WGS84 and the Greenwich Meridian". The Greenwich Meridian. from the original on 8 July 2014. Retrieved 6 January 2013.
  • Hooker, Brian (2006), , archived from the original on 26 September 2018, retrieved 28 June 2019
  • Howse, Derek (1997), Greenwich Time and the Longitude, Phillip Wilson, ISBN 978-0-85667-468-6
  • Norgate, Jean; Norgate, Martin (2006), "Prime meridian", Old Hampshire Mapped, from the original on 28 December 2021, retrieved 13 January 2013
  • NGS datasheet station name form, National Geodetic Survey, 2016, from the original on 16 February 2016, retrieved 11 December 2016
  • Sobel, Dava; Andrewes, William J. H. (1998), The Illustrated Longitude, Fourth Estate, London

External links edit

  • "Where the Earth's surface begins—and ends", Popular Mechanics, December 1930
  • scanned TIFFs of the conference proceedings

prime, meridian, prime, meridian, redirects, here, earth, prime, meridian, often, called, prime, meridian, iers, reference, meridian, historical, meridian, based, greenwich, prime, meridian, arbitrarily, chosen, meridian, line, longitude, geographic, coordinat. Prime Meridian redirects here For Earth s prime meridian often called the Prime Meridian see IERS Reference Meridian For the historical meridian it is based on see Prime meridian Greenwich A prime meridian is an arbitrarily chosen meridian a line of longitude in a geographic coordinate system at which longitude is defined to be 0 Together a prime meridian and its anti meridian the 180th meridian in a 360 system form a great circle This great circle divides a spheroid like Earth into two hemispheres the Eastern Hemisphere and the Western Hemisphere for an east west notational system For Earth s prime meridian various conventions have been used or advocated in different regions throughout history 1 Earth s current international standard prime meridian is the IERS Reference Meridian It is derived but differs slightly from the Greenwich Meridian the previous standard 2 0 class notpageimage Modern IERS Reference Meridian on Earth Gerardus Mercator in his Atlas Cosmographicae 1595 used a prime meridian somewhere close to 25 W passing just to the west of Santa Maria Island in the Azores in the Atlantic Ocean His 180th meridian runs along the Strait of Anian Bering Strait A prime meridian for a planetary body not tidally locked or at least not in synchronous rotation is entirely arbitrary unlike an equator which is determined by the axis of rotation However for celestial objects that are tidally locked more specifically synchronous their prime meridians are determined by the face always inward of the orbit a planet facing its star or a moon facing its planet just as equators are determined by rotation Longitudes for the Earth and Moon are measured from their prime meridian at 0 to 180 east and west For all other Solar System bodies longitude is measured from 0 their prime meridian to 360 West longitudes are used if the rotation of the body is prograde or direct like Earth meaning that its direction of rotation is the same as that of its orbit East longitudes are used if the rotation is retrograde 3 Contents 1 History 2 International prime meridian 2 1 Prime meridian at Greenwich 2 2 IERS Reference Meridian 2 2 1 List of places 3 Prime meridian on other planetary bodies 4 List of historic prime meridians on Earth 5 See also 6 Notes 7 References 8 Works cited 9 External linksHistory editSee also History of longitude nbsp 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 1 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 28 900 N 76 633 E 28 900 76 633 Rohitaka Rohtak a city near the Kurukshetra 4 better source needed nbsp 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 a This is shown in the copies of Spain s Padron Real made by Diogo Ribeiro in 1527 and 1529 Sao 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 deviation line did not follow a line of longitude 8 nbsp 1571 Africa map by Abraham Ortelius with Cape Verde as its prime meridian nbsp 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 9 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 10 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 11 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 Germany 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 12 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 13 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 14 It was adopted for air navigation by the International Civil Aviation Organization on 3 March 1989 15 International prime meridian editSince 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 physically very close to each other Prime meridian at Greenwich edit nbsp The line of the Greenwich meridian at the Royal Observatory GreenwichMain article 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 16 b 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 18 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 to the west of the Airy Transit Circle a distance equivalent to roughly 2 seconds of longitude 19 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 20 21 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 edit Main article 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 22 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 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 23 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 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 24 25 c A current convention on the Earth uses the line of longitude 180 opposite the IRM as the basis for the International Date Line List of places edit Map all coordinates using OpenStreetMapDownload coordinates as KML GPX all coordinates GPX primary coordinates GPX secondary coordinates On Earth starting at the North Pole and heading south to the South Pole the IERS Reference Meridian as of 2016 passes through Co ordinates approximate Country territory or sea Notes90 0 N 0 0 E 90 000 N 0 000 E 90 000 0 000 North Pole Arctic Ocean85 46 N 0 0 E 85 767 N 0 000 E 85 767 0 000 EEZ of Greenland Denmark Exclusive Economic Zone EEZ of Greenland Denmark 81 39 N 0 0 E 81 650 N 0 000 E 81 650 0 000 Greenland Sea Greenland Sea80 29 N 0 0 E 80 483 N 0 000 E 80 483 0 000 EEZ of Svalbard Norway EEZ of Svalbard Norway 76 11 N 0 0 E 76 183 N 0 000 E 76 183 0 000 International waters International waters73 44 N 0 0 E 73 733 N 0 000 E 73 733 0 000 EEZ of Jan Mayen EEZ of Jan Mayen Norway 72 53 N 0 0 E 72 883 N 0 000 E 72 883 0 000 Norwegian Sea Norwegian Sea69 7 N 0 0 E 69 117 N 0 000 E 69 117 0 000 International waters International waters64 42 N 0 0 E 64 700 N 0 000 E 64 700 0 000 EEZ of Norway EEZ of Norway63 29 N 0 0 E 63 483 N 0 000 E 63 483 0 000 EEZ of Great Britain EEZ of Great Britain61 0 N 0 0 E 61 000 N 0 000 E 61 000 0 000 North Sea North Sea53 46 N 0 0 E 53 767 N 0 000 E 53 767 0 000 United Kingdom nbsp United Kingdom From Tunstall in East Riding to Peacehaven passing through Greenwich50 47 N 0 0 E 50 783 N 0 000 E 50 783 0 000 English Channel English Channel EEZ of Great Britain50 14 N 0 0 E 50 233 N 0 000 E 50 233 0 000 EEZ of France English Channel EEZ of France49 20 N 0 0 E 49 333 N 0 000 E 49 333 0 000 France nbsp France From Villers sur Mer to Gavarnie42 41 N 0 0 E 42 683 N 0 000 E 42 683 0 000 Spain nbsp Spain From Cilindro de Marbore to Castellon de la Plana39 56 N 0 0 E 39 933 N 0 000 E 39 933 0 000 Mediterranean Sea Mediterranean Sea Gulf of Valencia EEZ of Spain38 52 N 0 0 E 38 867 N 0 000 E 38 867 0 000 Spain nbsp Spain From El Verger to Calp38 38 N 0 0 E 38 633 N 0 000 E 38 633 0 000 Mediterranean Sea Mediterranean Sea EEZ of Spain37 1 N 0 0 E 37 017 N 0 000 E 37 017 0 000 EEZ of Algeria Mediterranean Sea EEZ of Algeria35 50 N 0 0 E 35 833 N 0 000 E 35 833 0 000 Algeria nbsp Algeria From Stidia to Algeria Mali border near Bordj Badji Mokhtar21 52 N 0 0 E 21 867 N 0 000 E 21 867 0 000 Mali nbsp Mali Passing through Gao15 00 N 0 0 E 15 000 N 0 000 E 15 000 0 000 Burkina Faso nbsp Burkina Faso11 7 N 0 0 E 11 117 N 0 000 E 11 117 0 000 Togo nbsp Togo For about 600 m11 6 N 0 0 E 11 100 N 0 000 E 11 100 0 000 Ghana nbsp Ghana For about 16 km10 58 N 0 0 E 10 967 N 0 000 E 10 967 0 000 Togo nbsp Togo For about 39 km10 37 N 0 0 E 10 617 N 0 000 E 10 617 0 000 Ghana nbsp Ghana From the Togo Ghana border near Bunkpurugu to TemaPassing through Lake Volta at 7 46 N 0 0 E 7 767 N 0 000 E 7 767 0 000 Lake Volta 5 37 N 0 0 E 5 617 N 0 000 E 5 617 0 000 EEZ of Ghana in Atlantic Ocean Atlantic Ocean EEZ of Ghana1 58 N 0 0 E 1 967 N 0 000 E 1 967 0 000 International waters International waters0 0 N 0 0 E 0 000 N 0 000 E 0 000 0 000 Equator Passing through the Equator see Null Island 51 43 S 0 0 E 51 717 S 0 000 E 51 717 0 000 EEZ of Bouvet Island EEZ of Bouvet Island Norway 57 13 S 0 0 E 57 217 S 0 000 E 57 217 0 000 International waters International waters60 0 S 0 0 E 60 000 S 0 000 E 60 000 0 000 Southern Ocean Southern Ocean International waters69 36 S 0 0 E 69 600 S 0 000 E 69 600 0 000 Antarctica Antarctica Queen Maud Land claimed by nbsp Norway90 0 S 0 0 E 90 000 S 0 000 E 90 000 0 000 Amundsen Scott South Pole Station Antarctica Amundsen Scott South Pole Station South PolePrime meridian on other planetary bodies editSee also Longitude planets Prime meridian planets redirects here 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 26 The second is the Stonyhurst heliographic coordinates system originated at Stonyhurst Observatory in Lancashire England In 1975 the prime meridian of Mercury was defined 27 28 to be 20 east of the crater Hun Kal 29 Defined 30 in 1992 the prime meridian of Venus passes through the central peak in the crater Ariadne 31 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 32 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 33 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 34 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 35 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 36 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 List of historic prime meridians on Earth editLocality Modern longitude Meridian name Image CommentBering Strait 168 30 W nbsp 168 class notpageimage 168th meridian west Offered in 1884 as possibility for a neutral prime meridian by Pierre Janssen at the International Meridian Conference 37 Washington D C 77 03 56 07 W 1897 or 77 04 02 24 W NAD 27 clarification needed or 77 04 01 16 W NAD 83 New Naval Observatory meridian nbsp 77 class notpageimage 77th meridian west77 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 meridian77 02 11 56299 W NAD 83 38 77 02 11 55811 W NAD 83 39 77 02 11 58325 W NAD 83 40 three different monuments originally intended to be on the White House meridian White House meridian77 00 32 6 W NAD 83 Capitol meridianPhiladelphia 75 10 12 W nbsp 75 class notpageimage 75th meridian west 41 42 Rio de Janeiro 43 10 19 W nbsp 43 class notpageimage 43rd meridian west 43 Fortunate Isles Azores 25 40 32 W nbsp 25 class notpageimage 25th meridian west Used until the Middle Ages proposed as one possible neutral meridian by Pierre Janssen at the International Meridian Conference 44 El Hierro Ferro Canary Islands 18 03 W later redefined as 17 39 46 W Ferro meridian nbsp 18 class notpageimage 18th meridian west 45 Tenerife 16 38 22 W Tenerife meridian nbsp 16 class notpageimage 16th meridian west Rose to prominence with Dutch cartographers and navigators after they abandoned the idea of a magnetic meridian 46 Lisbon 9 07 54 862 W nbsp 9 class notpageimage 9th meridian west 47 Cadiz 6 17 35 4 W Cadiz meridian nbsp 6 class notpageimage 6th meridian west Royal Observatory in southeast tower of Castillo de la Villa used 1735 1850 by Spanish Navy 48 49 Madrid 3 41 16 58 W nbsp 3 class notpageimage 3rd meridian west 47 Kew 0 00 19 0 W Prime Meridian prior to Greenwich nbsp 0 class notpageimage Prime meridian Located at King George III s Kew ObservatoryGreenwich 0 00 05 33 W United Kingdom Ordnance Survey Zero Meridian Bradley Meridian 19 0 00 05 3101 W Greenwich meridian Airy Meridian 19 0 00 00 00 IERS Reference MeridianParis 2 20 14 025 E Paris meridian nbsp 2 class notpageimage 2nd meridian eastBrussels 4 22 4 71 E nbsp 4 class notpageimage 4th meridian east 47 Antwerp 4 24 E Antwerp meridianAmsterdam 4 53 E Through the Westerkerk in Amsterdam used to define the legal time in the Netherlands from 1909 to 1937 50 Pisa 10 24 E nbsp 10 class notpageimage 10th meridian east 41 Oslo Kristiania 10 43 22 5 E 41 42 Florence 11 15 E Florence meridian nbsp 11 class notpageimage 11th meridian east Used in the Peters projection 180 from a meridian running through the Bering StraitRome 12 27 08 4 E Meridian of Monte Mario nbsp 12 class notpageimage 12th meridian east Used in Roma 40 Datum 51 Copenhagen 12 34 32 25 E Rundetarn 52 Naples 14 15 E nbsp 14 class notpageimage 14th meridian east 44 Pressburg 17 06 03 E Meridianus Posoniensis nbsp 17 class notpageimage 17th meridian east Used by Samuel MikovinyStockholm 18 03 29 8 E nbsp 18 class notpageimage 18th meridian east At the Stockholm Observatory 47 Buda 19 03 37 E Meridianu s Budense nbsp 19 class notpageimage 19th meridian east Used between 1469 and 1495 introduced by Regiomontanus used by Marcin Bylica Galeotto Marzio Miklos Erdelyi 1423 1473 Johannes Tolhopff c 1445 1503 Johannes Muntz Set in the royal castle and observatory of Buda d Krakow 19 57 21 43 E Krakow meridian at the Old Krakow Observatory at the Sniadecki College mentioned also in Nicolaus Copernicus s work On the Revolutions of the Heavenly Spheres Warsaw 21 00 42 E Warsaw meridian nbsp 21 class notpageimage 21st meridian east 47 Varad 21 55 16 E Tabulae Varadienses nbsp 21 class notpageimage 21st meridian east 56 Between 1464 and 1667 a prime meridian was set in the Fortress of Oradea Varadinum at the time by Georg von Peuerbach 57 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 Varad Amerigo Vespucci also recalled how was he acquired the knowledge to calculate meridians by means of these tables 58 Alexandria 29 53 E Meridian of Alexandria nbsp 29 class notpageimage 29th meridian east The meridian of Ptolemy s Almagest Saint Petersburg 30 19 42 09 E Pulkovo meridian nbsp 30 class notpageimage 30th meridian eastGreat Pyramid of Giza 31 08 03 69 E nbsp 31 class notpageimage 31st meridian east 1884 59 Jerusalem 35 13 47 1 E nbsp 35 class notpageimage 35th meridian east 42 Mecca 39 49 34 E nbsp 39 class notpageimage 39th meridian east See also Mecca TimeApprox 59 E nbsp 59 class notpageimage 59th meridian east Maimonides 60 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 nbsp 75 class notpageimage 75th meridian east Used from 4th century CE Indian astronomy and calendars see also Time in India 61 Kyoto 136 14 E nbsp 136 class notpageimage 136th meridian east 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 citation needed 180 nbsp 180 class notpageimage 180th meridian Opposite of Greenwich proposed 13 October 1884 on the International Meridian Conference by Sandford Fleming 44 See also edit1st meridian east Line of longitude 1st meridian west Line of longitude 180th meridian Line of longitude Null Island Cartographical only marker at 0 N 0 E Geographical center of Earth Geometric centre of all land surfaces on EarthPages displaying short descriptions of redirect targetsNotes edit These figures use the legua nautica nautical league of four Roman miles totalling 5 926 km 3 682 mi which was used by Spain during the 15th 16th and 17th centuries for navigation 5 In 1897 Henry Harrise noted that Jaime Ferrer the expert consulted by King Ferdinand and Queen Isabella stated that a league was four miles of six stades each 6 Modern scholars agree that the geographic stade was the Roman or Italian stade not any of several other Greek stades supporting these figures 7 Harrise is in the minority when he uses the stade of 192 27 m 630 8 ft marked within the stadium at Olympia Greece resulting in a league 32 stades of 6 153 km 3 823 mi 3 8 larger Voting took place on 13 October and the resolutions were adopted on 22 October 1884 17 The modern prime meridian the IERS Reference Meridian is placed very near this meridian 13 The astronomic latitude of the Royal Observatory is 51 28 38 N whereas its latitude on the European Terrestrial Reference Frame 1989 datum is 51 28 40 1247 N When Tolhopff handed over his book titled Stellarium 1480 53 to King Matthias Corvinus he emphasized that he had used the meridian of Buda for his calculations The German physician Johannes Muntz used it the same way in his 1495 calendar However in the second edition he used the Vienna meridian 54 55 References edit a b Norgate amp Norgate 2006 What is the Prime Meridian and why is it in Greenwich Royal Museums Greeenwich Archived from the original on 13 December 2021 Retrieved 13 December 2021 The IRM is the only meridian that may now be described as the prime meridian of the world as it defines 0 longitude by international agreement The IRM passes 102 5 metres to the east of the historic Prime Meridian of the World at the latitude of the Airy Transit Circle here The entire Observatory and the historic Prime Meridian now lie to the west of the true prime meridian Archimal B A 2015 Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements 2015 PDF p 27 of 46 archived PDF from the original on 6 August 2019 retrieved 6 August 2019 The range of longitudes shall extend from 0 to 360 Thus west longitudes are used when the rotation is direct and east longitudes are used when the rotation is retrograde The Earth Sun and Moon do not traditionally follow this definition Their rotations are direct and longitudes run both east and west 180 or positive to the east 360 Schmidt Olaf H 1944 The Computation of the Length of Daylight in Hindu Astronomy Isis The University of Chicago Press 35 3 205 211 doi 10 1086 358709 JSTOR 330729 S2CID 145178197 Archived from the original on 26 January 2022 Chardon Roland 1980 The linear league in North America Annals of the Association of American Geographers 70 2 129 153 pp 142 144 151 doi 10 1111 j 1467 8306 1980 tb01304 x JSTOR 2562946 Harrisse Henry 1897 The Diplomatic History of America Its first chapter 1452 1493 1494 London Stevens pp 85 97 176 190 ISBN 9780697000071 OCLC 1101220811 Engels Donald 1985 The length of Eratosthenes stade American Journal of Philology 106 3 298 311 doi 10 2307 295030 JSTOR 295030 Hooker 2006 e g Jacob Roggeveen in 1722 reported the longitude of Easter Island as 268 45 starting from Fuerteventura in the Extract from the Official log of Jacob Roggeveen reproduced in Bolton Glanville Corney ed 1908 The voyage of Don Felipe Gonzalez to Easter Island in 1770 1 Hakluyt Society p 3 retrieved 13 January 2013 Speech by Pierre Janssen director of the Paris observatory at the first session of the Meridian Conference Archived 18 December 2021 at the Wayback Machine Sobel amp Andrewes 1998 pp 110 115 Sobel amp Andrewes 1998 pp 197 199 a b What is the Prime Meridian and why is it in Greenwich Who decided that the Prime Meridian should be in Greenwich Royal Museums Greenwich n d Archived from the original on 5 January 2022 Retrieved 28 December 2021 A manual on the technical aspects of the United Nations Convention on the Law of the Sea 1982 PDF Archived PDF from the original on 10 September 2008 Retrieved 23 July 2008 4 89 MB Section 2 4 4 WGS 84 Implementation Manual Archived 3 October 2008 at the Wayback Machine page i 1998 International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day October 1884 Protocols of the proceedings Project Gutenberg 1884 Archived from the original on 18 December 2021 Retrieved 30 November 2012 Howse 1997 pp 12 137 Forbes Eric Gray 1975 Greenwich Observatory the story of Britain s oldest scientific institution the Royal Observatory at Greenwich and Herstmonceux 1675 1975 Vol 1 Taylor amp Francis p 10 ISBN 9780850660937 a b c Dolan 2013a McCarthy Dennis Seidelmann P Kenneth 2009 TIME from Earth Rotation to Atomic Physics Weinheim Wiley VCH pp 244 5 ROG Learning Team 23 August 2002 The Prime Meridian at Greenwich Royal Museums Greenwich Archived from the original on 7 November 2015 Retrieved 14 June 2012 Malys Stephen Seago John H Palvis Nikolaos K Seidelmann P Kenneth Kaplan George H 1 August 2015 Why the Greenwich meridian moved Journal of Geodesy 89 12 1263 Bibcode 2015JGeod 89 1263M doi 10 1007 s00190 015 0844 y Dolan 2013b Greenwich Meridan Tracing its History gpsinformation net Archived from the original on 19 December 2017 Retrieved 29 November 2006 IRM on grounds of Royal Observatory from Google Earth Archived 14 October 2016 at the Wayback Machine Accessed 30 March 2012 Carrington heliographic coordinates Archived from the original on 28 June 2011 Retrieved 27 July 2009 Merton E Davies Surface Coordinates and Cartography of Mercury Journal of Geophysical Research Vol 80 No 17 10 June 1975 Merton E Davies S E Dwornik D E Gault and R G Strom NASA Atlas of Mercury NASA Scientific and Technical Information Office 1978 Archinal Brent A A Hearn Michael F Bowell Edward G Conrad Albert R Consolmagno Guy J et al 2010 Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements 2009 PDF Celestial Mechanics and Dynamical Astronomy 109 2 101 135 Bibcode 2011CeMDA 109 101A doi 10 1007 s10569 010 9320 4 S2CID 189842666 Archived from the original PDF on 4 March 2016 Retrieved 26 September 2018 Merton E Davies Colvin T R Rogers P G Chodas P G Sjogren W L Akim W L Stepanyantz E L Vlasova Z P and Zakharov A I The Rotation Period Direction of the North Pole and Geodetic Control Network of Venus Journal of Geophysical Research vol 97 no 8 1992 pp 1 14 151 USGS Astrogeology Rotation and pole position for the Sun and planets IAU WGCCRE Archived from the original on 24 October 2011 Retrieved 22 October 2009 Merton E Davies and Berg R A Preliminary Control Net of Mars Journal of Geophysical Research vol 76 no 2 10 January 1971 pp 373 393 Archinal Brent A Acton C H A Hearn Michael F Conrad Albert R et al 2018 Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements 2015 Celestial Mechanics and Dynamical Astronomy 130 22 22 Bibcode 2018CeMDA 130 22A doi 10 1007 s10569 017 9805 5 S2CID 189844155 Planetographic Coordinates Archived from the original on 15 April 2012 Retrieved 24 May 2017 Merton E Davies Thomas A Hauge et al Control Networks for the Galilean Satellites November 1979 R 2532 JPL NASA Merton E Davies P G Rogers and T R Colvin A Control Network of Triton Journal of Geophysical Research Vo l 96 E l pp 15 675 15 681 1991 International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day October 1884 Archived 18 December 2021 at the Wayback Machine pp 43 51 Project Gutenberg NGS 2016 PID HV1847 NGS 2016 PID HV1846 NGS 2016 PID AH7372 a b c Hooker 2006 introduction a b c Oct 13 1884 Greenwich Resolves Subprime Meridian Crisis Archived 1 December 2018 at the Wayback Machine WIRED 13 October 2010 Atlas do Brazil Archived 16 June 2014 at the Wayback Machine 1909 by Barao Homem de Mello e Francisco Homem de Mello published in Rio de Janeiro by F Briguiet amp Cia a b c The Project Gutenberg eBook of International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day Gutenberg org 12 February 2006 Archived from the original on 18 December 2021 Retrieved 28 March 2016 Ancient used in Ptolemy s Geographia Later redefined 17 39 46 W of Greenwich to be exactly 20 W of Paris French submarin at Washington 1884 A R T Jonkers Parallel meridians Diffusion and change in early modern oceanic reckoning Archived 26 January 2018 at the Wayback Machine in Noord Zuid in Oostindisch perspectief The Hague 2005 p 7 Retrieved 2 February 2015 a b c d e Bartky Ian R 2007 One Time Fits All The Campaigns for Global Uniformity Stanford University Press p 98 ISBN 978 0 8047 5642 6 Archived from the original on 22 January 2023 Retrieved 8 December 2018 In search of the lost meridian of Cadiz Archived 30 November 2019 at the Wayback Machine El Pais 23 December 2016 Retrieved 8 November 2018 Antonio Lafuente and Manuel Selles El Observatorio de Cadiz 1753 1831 Archived 2 June 2020 at the Wayback Machine Ministerio de Defensa 1988 p 144 ISBN 84 505 7563 X in Spanish in Dutch Eenheid van tijd in Nederland Unity of time in the Netherlands Archived 10 February 2015 at the Wayback Machine Utrecht University website retrieved 28 August 2013 Grids amp Datums Italian Republic Archived 20 November 2012 at the Wayback Machine asprs org Retrieved 10 December 2013 meridian Archived 14 March 2016 at the Wayback Machine article from Den Store Danske Encyklopaedi Tolhopff Johannes 1480 Stellarium in Latin Archived from the original on 30 December 2021 Retrieved 30 December 2021 facsimile not machine readable Zsoldos Endre 2014 Stellarium egy csillagaszati kodex Matyas konyvtaraban Stellarium an Astronomical Codex in the Library of King Matthias Orpheus Noster in Hungarian 5 4 64 87 Szathmary Laszlo 2002 Az asztrologia alkemia es misztika Matyas kiraly udvaraban Astrology alchemy and mysticism in the court of King Matthias Ponticulus Hungaricus in Hungarian VI evfolyam 5 szam Archived from the original on 18 October 2009 Retrieved 27 December 2018 Oradea Romania Tourism Archived from the original on 6 February 2015 Retrieved 3 February 2015 Romanian astronaut marks 10th anniversary of Prime Meridian Astronomy Club NineO Clock 2015 Archived from the original on 1 October 2017 Retrieved 26 June 2017 Meridian Zero csillagaszklub in Romanian Archived from the original on 12 April 2009 Retrieved 27 December 2018 Wilcomb E Washburn The Canary Islands and the Question of the Prime Meridian The Search for Precision in the Measurement of the Earth Archived 29 May 2007 at the Wayback Machine Hilchot Kiddush Hachodesh 11 17 Burgess 1860 Works cited editBurgess Ebenezer 1860 Translation of the Surya Siddhanta Journal of the American Oriental Society e book vol 6 published 2013 p 185 Dolan Graham 2013a The Greenwich Meridian before the Airy Transit Circle The Greenwich Meridian Archived from the original on 2 May 2012 Retrieved 6 January 2013 Dolan Graham 2013b WGS84 and the Greenwich Meridian The Greenwich Meridian Archived from the original on 8 July 2014 Retrieved 6 January 2013 Hooker Brian 2006 A multitude of prime meridians archived from the original on 26 September 2018 retrieved 28 June 2019 Howse Derek 1997 Greenwich Time and the Longitude Phillip Wilson ISBN 978 0 85667 468 6 Norgate Jean Norgate Martin 2006 Prime meridian Old Hampshire Mapped archived from the original on 28 December 2021 retrieved 13 January 2013 NGS datasheet station name form National Geodetic Survey 2016 archived from the original on 16 February 2016 retrieved 11 December 2016 Sobel Dava Andrewes William J H 1998 The Illustrated Longitude Fourth Estate LondonExternal links edit nbsp Wikimedia Commons has media related to Prime meridian Where the Earth s surface begins and ends Popular Mechanics December 1930 scanned TIFFs of the conference proceedings Prime meridians in use in the 1880s by country Portals nbsp Geography nbsp Earth sciences nbsp Astronomy nbsp Stars nbsp Spaceflight nbsp Outer space nbsp Solar System Retrieved from https en wikipedia org w index php title Prime meridian amp oldid 1185791913, wikipedia, wiki, book, books, library,

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