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Prime Meridian
Nations that touch the Equator (red) and the Prime Meridian (blue)
.The Prime Meridian is the meridian (line of longitude) at which the longitude is defined to be 0°.^ Greenwich is now the prime meridian for longitude .
  • The Secret Voyage of Sir Francis Drake 2 February 2010 9:26 UTC www.reformation.org [Source type: FILTERED WITH BAYES]

^ Define prime meridian .

^ Latitude, longitude and the prime meridian Latitude, Longitude and the Prime Meridian .
  • Latitude, longitude and the prime meridian 2 February 2010 9:26 UTC www.uta.edu [Source type: Reference]

.The Prime Meridian and its opposite the 180th meridian (at 180° longitude), which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.^ Each longitude can be thought of as dividing the Earth in half.

^ In what 2 hemispheres dose prime meridian divides earth into?
  • WikiAnswers - The prime meridian helps to divide the earth into which two hemispheres 2 February 2010 9:26 UTC wiki.answers.com [Source type: General]

^ All meridians are great circles.
  • Maps101--Advanced Glossary 2 February 2010 9:26 UTC www.maps101.com [Source type: FILTERED WITH BAYES]

.By international convention, the modern Prime Meridian passes through the Royal Observatory, Greenwich (at 51°28′38″N 0°00′00″E / 51.47722°N 0°E / 51.47722; 0 (Greenwich Observatory)), in southeast London, United Kingdom, known as the International Meridian or Greenwich Meridian, although the Prime Meridian is ultimately arbitrary unlike the parallels of latitude, which are defined by the rotational axis of the Earth with the Poles at 90° and the Equator at 0°.^ Why does the Prime Meridian go through Greenwich, England?
  • Latitude and Longitude 2 February 2010 9:26 UTC www.windows.ucar.edu [Source type: FILTERED WITH BAYES]

^ They are known as "parallels" of latitude, because they run parallel to the equator.
  • Understanding Latitude and Longitude 2 February 2010 9:26 UTC www.learner.org [Source type: FILTERED WITH BAYES]

^ With a value of 0?, the prime meridian passes through Greenwich, England.
  • NASA's KSNN™ 2 February 2010 9:26 UTC ksnn.larc.nasa.gov [Source type: FILTERED WITH BAYES]

.Historically, various meridians have been used, including four different ones through Greenwich.^ The International Meridian Conference of 1884 adopted the Prime Meridian line passing through the Greenwich Observatory near London, England.
  • Cynthia Lanius' Lessons: Mathematics of Cartography:Map Coordinate System 2 February 2010 9:26 UTC math.rice.edu [Source type: Reference]

^ The second was that in the late 19th century, 72 per cent of the world's commerce depended on sea-charts, which used Greenwich as the Prime Meridian.
  • The Meridian Line - Ghanamma.com-Ghana News,Breaking News,Ghana Movies,Music Videos,Sports,Chat,Recipes,Business 2 February 2010 9:26 UTC www.ghanamma.com [Source type: General]

^ In 1884, a conference in Washington, D.C. settled the matter where it was agreed to establish a single "prime" meridian (0° longitude), passing through Greenwich.
  • NWS JetStream - Clouds 2 February 2010 9:26 UTC www.srh.noaa.gov [Source type: News]

Contents

Geography

Starting at the North Pole and heading south to the South Pole, the Prime Meridian passes through:
Co-ordinates
(approximate)
Country, territory or sea Notes
90°0′N 0°0′E / 90°N 0°E / 90; 0 (North Pole) Arctic Ocean The North Pole
81°39′N 0°0′E / 81.65°N 0°E / 81.65; 0 (Greenland Sea) Greenland Sea
72°53′N 0°0′E / 72.883°N 0°E / 72.883; 0 (Norwegian Sea) Norwegian Sea
61°0′N 0°0′E / 61°N 0°E / 61; 0 (North Sea) North Sea
53°45′N 0°0′E / 53.75°N 0°E / 53.75; 0 (United Kingdom)  United Kingdom The northmost piece of land on this meridian is near Tunstall in East Riding,Yorkshire.
50°47′N 0°0′E / 50.783°N 0°E / 50.783; 0 (English Channel) English Channel
49°19′N 0°0′E / 49.317°N 0°E / 49.317; 0 (France)  France
42°41′N 0°0′E / 42.683°N 0°E / 42.683; 0 (Spain)  Spain
39°56′N 0°0′E / 39.933°N 0°E / 39.933; 0 (Mediterranean Sea) Mediterranean Sea Gulf of Valencia
38°52′N 0°0′E / 38.867°N 0°E / 38.867; 0 (Spain)  Spain
38°38′N 0°0′E / 38.633°N 0°E / 38.633; 0 (Mediterranean Sea) Mediterranean Sea
35°50′N 0°0′E / 35.833°N 0°E / 35.833; 0 (Algeria)  Algeria
21°50′N 0°0′E / 21.833°N 0°E / 21.833; 0 (Mali)  Mali
14°59′N 0°0′E / 14.983°N 0°E / 14.983; 0 (Burkina Faso)  Burkina Faso
11°6′N 0°0′E / 11.1°N 0°E / 11.1; 0 (Togo)  Togo For about 600 m
11°6′N 0°0′E / 11.1°N 0°E / 11.1; 0 (Ghana)  Ghana For about 16 km
10°57′N 0°0′E / 10.95°N 0°E / 10.95; 0 (Togo)  Togo
10°36′N 0°0′E / 10.6°N 0°E / 10.6; 0 (Ghana)  Ghana Passing through Lake Volta at 7°48′N 0°0′E / 7.8°N 0°E / 7.8; 0 (Lake Volta)
5°37′N 0°0′E / 5.617°N 0°E / 5.617; 0 (Atlantic Ocean) Atlantic Ocean Passing through the Equator at 0°0′N 0°0′E / 0°N 0°E / 0; 0 (Equator)
60°0′S 0°0′E / 60°S 0°E / -60; 0 (Southern Ocean) Southern Ocean
68°54′S 0°0′E / 68.9°S 0°E / -68.9; 0 (Antarctica) Antarctica Queen Maud Land, claimed by  Norway to the South Pole at 90°0′S 0°0′E / 90°S 0°E / -90; 0 (South Pole)

History

The Royal Observatory, Greenwich (today a museum)
Prime Meridian in Greenwich
The Prime Meridian is ultimately arbitrary — a matter of convention — and various conventions have been used or advocated throughout history:
.
  • Washington, D.C. (77° 3' 2.3” W), see Washington meridian
  • Philadelphia (75° 10' 12” W)
  • Rio de Janeiro (43° 10' 19” W)[1]
  • El Hierro (Ferro), Canary Islands (18° 03' W), later redefined as 17° 39' 46”?^ Announces Return of Managing Director Marketwire News Releases Published: 01/15/10 12:04 PM EST Released By: Meridian Co., Ltd.
    • PE.com | Southern California News | News for Inland Southern California 2 February 2010 9:26 UTC markets.pe.com [Source type: News]
    • Stock Watch | RCR Wireless News 2 February 2010 9:26 UTC stocks.rcrwireless.com [Source type: News]
    • About - Business & Finance - MEDIAVIEWER 2 February 2010 9:26 UTC markets.about.com [Source type: News]
    • Business - wcbstv.com 2 February 2010 9:26 UTC business.wcbstv.com [Source type: News]
    • Meridian Co. Announces Return of Managing Director - news from Boston.com 2 February 2010 9:26 UTC finance.boston.com [Source type: News]
    • Denver Post: Stocks 2 February 2010 9:26 UTC finance.denverpost.com [Source type: General]
    • Nation's Restaurant News 2 February 2010 9:26 UTC finance.nrn.com [Source type: News]
    • Stock Portfolio Lokup Login | NewsOK.com 2 February 2010 9:26 UTC stocks.newsok.com [Source type: News]
    • Business - cbs11tv.com 2 February 2010 9:26 UTC business.cbs11tv.com [Source type: News]
    • Business - cbs4.com 2 February 2010 9:26 UTC business.cbs4.com [Source type: News]

    ^ The prime meridian in this map passes through the Canary Islands.
    • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

    ^ Only one chart in the collection has the longitude marked upon it and the prime meridian in this print passes through the Canary Islands between Gomera and Tenerife.
    • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

    .W)[2]
  • Lisbon (9° 07' 54.862” W)
  • Madrid (3° 41' 16.58” W)
  • Paris (2° 20' 14.025” E), see Paris Meridian
  • Brussels (4° 22' 4.71” E)
  • Berne (7° 26' 22.5” E)
  • Pisa, Italy (10°24' E)
  • Oslo (Kristiania) (10° 43' 22.5” E)
  • Rome (12° 27' 08.4” E), meridian of Mount Mario
  • Copenhagen (12° 34' 32.25” E) Rundetårn
  • Stockholm (18° 3' 29.8” E), at the observatory
  • Warsaw (21° 00’ 42” E), see Warsaw meridian
  • Oradea, Romania (21° 55' 16” E)
  • Alexandria (29° 53' E)[3]
  • Saint Petersburg (30° 19' 42.09” E), Pulkovo meridian
  • Great Pyramid of Giza (31° 8' 3.69” E), 1884 [4]
  • Jerusalem (35° 13' 47.1” E), for the small dome of the Church of the Holy Sepulchre
  • Mecca (39° 49' E)
  • Approximately 59° east of Greenwich [5]
  • Ujjain (75° 47' E), Used from 4th century CE Indian astronomy and calendars.
  • Kyoto (135° 74' E), Used in 18th and 19th (officially 1779-1871) century Japanese maps.^ Announces Return of Managing Director Marketwire News Releases Published: 01/15/10 12:04 PM EST Released By: Meridian Co., Ltd.
    • PE.com | Southern California News | News for Inland Southern California 2 February 2010 9:26 UTC markets.pe.com [Source type: News]
    • Finance | paidContent 2 February 2010 9:26 UTC finance.paidcontent.org [Source type: News]
    • About - Business & Finance - MEDIAVIEWER 2 February 2010 9:26 UTC markets.about.com [Source type: News]
    • Meridian Co. Announces Return of Managing Director - news from Boston.com 2 February 2010 9:26 UTC finance.boston.com [Source type: News]
    • http://markets.sltrib.com/mng-sltrib/?GUID=11494781&Page=MEDIAVIEWER 2 February 2010 9:26 UTC markets.sltrib.com [Source type: News]
    • Clusterstock Stock Pages 2 February 2010 9:26 UTC financial.businessinsider.com [Source type: General]

    ^ In the Mean Earth / Polar Axis system, Msting A is at 3°12'43.2"S, 5°12'39.6"W, not on the Equator or the Prime Meridian (Rkl 1990).
    • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

    ^ And the fact that Britain was a super power, an industrial power, a great might in the 19th century, one of the reasons why the prime meridian was fixed on this spot in Greenwich.
    • The Prime Meridian: A Climate Journey's Guide : NPR 2 February 2010 9:26 UTC www.npr.org [Source type: General]

    Exact place unknown, but in "Kairekisyo" in Nishigekkoutyou-town in Kyoto, then the capital.
Laser projected from the Royal Observatory in Greenwich marking the Prime Meridian
.The modern Greenwich Meridian, based at the Royal Observatory, Greenwich, was established by Sir George Airy in 1851. By 1884, over two-thirds of all ships and tonnage used it as the reference meridian on their maps.^ Each Meridian unit ships with a base map.
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

^ In Britain the OSGB1936 datum is used as map datum, so the prime meridian at Greenwich is based on this datum.
  • Where is the prime meridian? - PDA street forums 2 February 2010 9:26 UTC www.pdastreet.com [Source type: FILTERED WITH BAYES]

^ All three maps in his Travels used the Yale Prime Meridian.
  • http://www.cartographicarts.com/catalog.html?cat=antique_maps&id=9 2 February 2010 9:26 UTC www.cartographicarts.com [Source type: FILTERED WITH BAYES]

.In October of that year, at the behest of U.S. President Chester A. Arthur, 41 delegates from 25 nations met in Washington, D.C., USA, for the International Meridian Conference.^ In 1884 , the International Meridian Conference adopted the Greenwich meridian as the universal prime meridian or zero point of longitude .
  • Longitude | Koordinaten / Informationen / Encyclopedia of terms - Longitude 2 February 2010 9:26 UTC www.koordinaten.de [Source type: FILTERED WITH BAYES]

^ Description: In October 1884 41 delegates from 25 countries met in Washington DC for the International Meridian Conference.
  • October 21st: 125 years of the Prime Meridian at Greenwich 2 February 2010 9:26 UTC 365daysofastronomy.org [Source type: General]

^ So after years of discussion, the conference hoped that if the entire world was to accept Greenwich as the prime meridian, Great Britain might be prepared to conform to the metric system.

.This conference selected the Greenwich Meridian as the official Prime Meridian due to its popularity.^ Prime meridian Greenwich.
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]

^ The Greenwich meridian, however, remained the prime meridian.
  • Navis.gr - Latitude and Longitude 2 February 2010 9:26 UTC www.navis.gr [Source type: FILTERED WITH BAYES]

^ GREENWICH MERIDIAN see prime meridian .
  • Prime Meridian: Free Encyclopedia Articles at Questia.com Online Library 2 February 2010 9:26 UTC www.questia.com [Source type: Academic]

.However, France abstained from the vote and French maps continued to use the Paris Meridian for several decades.^ So, the Greenwich Meridian was finally passed at the International Meridian Conference held in Washington, DC, and attended by delegates for 41 nations (Santo Domingo was the sole no vote, and France and Brazil abstained).
  • Lecture: Longitude, Dr. Rodrigue 2 February 2010 9:26 UTC www.csulb.edu [Source type: FILTERED WITH BAYES]

^ The one inch map of Surrey by Andrews and Dury, 1777, uses a prime meridian through St Paul's Cathedral, London.
  • Maps, prime meridian 2 February 2010 9:26 UTC www.geog.port.ac.uk [Source type: FILTERED WITH BAYES]

^ British charts used Greenwich but French charts used Paris and some others used Cadiz and other places.
  • October 21st: 125 years of the Prime Meridian at Greenwich 2 February 2010 9:26 UTC 365daysofastronomy.org [Source type: General]

.The Greenwich Meridian is now marked at night by a laser beam emitted northwards from the observatory.^ Greenwich is now the prime meridian for longitude .
  • The Secret Voyage of Sir Francis Drake 2 February 2010 9:26 UTC www.reformation.org [Source type: FILTERED WITH BAYES]

^ By international convention, it passes through the original site of the Royal Observatory in Greenwich, England; for this reason, it is sometimes called the Greenwich meridian.
  • prime meridian Facts, information, pictures | Encyclopedia.com articles about prime meridian 2 February 2010 9:26 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

^ The 125th anniversary of the Prime Meridian will be celebrated with a talk by Graham Dolan at the Royal Observatory in Greenwich at 1900 BST on Tuesday 20 October.
  • BBC NEWS | UK | Magazine | At the centre of time 2 February 2010 9:26 UTC news.bbc.co.uk [Source type: News]
  • BBC NEWS | UK | Magazine | At the centre of time 2 February 2010 9:26 UTC news.bbc.co.uk [Source type: News]


IERS Reference Meridian

.
A GPS receiver at the Greenwich Meridian.
^ The Flamsteed Astronomy Society has explained the implications of this quite nicely: It is true that a GPS receiver held over the Meridian Line at Greenwich will NOT read longitude (0,0).
  • Greenwich Longitude off by 106m in Keyhole? - Google Earth Community 2 February 2010 9:26 UTC bbs.keyhole.com [Source type: General]

^ Difference between Magellan SporTrak and Meridian GPS receivers?
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

^ This document covers the most commonly asked questions about the Magellan Meridian line of mapping GPS receivers.
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

This does not indicate a longitude of zero because the GPS Prime Meridian is about 100 metres to the east.
.The International Earth Rotation and Reference Systems Service (IERS) maintains the IERS Reference Meridian (IRM), also called the International Reference Meridian, which is the reference meridian (Prime Meridian, 0° longitude) of the Global Positioning System operated by the United States Department of Defense, and is the reference meridian in WGS84 and in its formal versions, the ideal International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF).^ It is 5.79 metres W of the international Prime Meridian.
  • Maps, prime meridian 2 February 2010 9:26 UTC www.geog.port.ac.uk [Source type: FILTERED WITH BAYES]

^ This meridian is called the International Date Line .

^ Greenwich is now the prime meridian for longitude .
  • The Secret Voyage of Sir Francis Drake 2 February 2010 9:26 UTC www.reformation.org [Source type: FILTERED WITH BAYES]

.It is 5.31″ east of Airy's transit circle or 102.5 metres (336.3 feet) at the latitude of the Royal Observatory, Greenwich.^ By international convention, it passes through the original site of the Royal Observatory in Greenwich, England; for this reason, it is sometimes called the Greenwich meridian.
  • prime meridian Facts, information, pictures | Encyclopedia.com articles about prime meridian 2 February 2010 9:26 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

^ An international conference held in Washington, D.C., in 1884 designated “the meridian passing through the centre of the transit instrument at the Observatory of Greenwich as the initial meridian for longitude.” The observatory (renamed the Royal Greenwich Observatory ) was moved to Hailsham, East Sussex , during the 1950s, but the original site continues to serve as the location for 0° longitude.
  • Greenwich meridian (geography) -- Britannica Online Encyclopedia 2 February 2010 9:26 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ By the end of the month, after heated debate, the meridian line defined by the Airy Transit Circle telescope at the Royal Observatory in Greenwich had been selected as longitude 0 degrees.
  • October 21st: 125 years of the Prime Meridian at Greenwich 2 February 2010 9:26 UTC 365daysofastronomy.org [Source type: General]

[6] This shift is a legacy of the first satellite navigation system, the Doppler based TRANSIT system developed by the Applied Physics Laboratory of Johns Hopkins University in Howard County, Maryland. .This was the location of its first ground station, so the surveyed coordinates of that ground station in the North American Datum 1927 (NAD27), a non-Earth centered ellipsoid, became its coordinates in an Earth-centered ellipsoid, such as the World Geodetic System.^ In many places (notably North America and Austrialia) national geodetic organizations provide grid shift files for converting between different datums, such as NAD27 to NAD83.
  • GenParms - PROJ.4 - Trac 2 February 2010 9:26 UTC trac.osgeo.org [Source type: Reference]

^ Once the earth's round, three-dimensional shape was accepted, a spherical coordinate system was created to determine locations around the world.
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ Most maps allow us to specify the location of points on the Earth's surface using a coordinate system.

.This caused the coordinates of any other location on an Earth-centered ellipsoid to shift, especially those far away.^ Once the earth's round, three-dimensional shape was accepted, a spherical coordinate system was created to determine locations around the world.
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ Most maps allow us to specify the location of points on the Earth's surface using a coordinate system.

^ Geographic grid – Spherical coordinate system used for finding locations on the earth's surface.
  • Maps101--Advanced Glossary 2 February 2010 9:26 UTC www.maps101.com [Source type: FILTERED WITH BAYES]

.When the antenna of a TRANSIT ground station was mounted directly above Airy's transit instrument in June 1969, its longitude on an Earth-centered ellipsoid was 5.64″ west of TRANSIT's reference meridian.^ Longitude measures the west-east position of locations on the Earth's surface relative to a circular arc called the Prime Meridian ( Figure 2b-2 ).

^ This unit provides an overview of latitude and longitude, including: Earth rotation, the North and South Poles, and the Equator Parallels of latitude and meridians of longitude Determination of north or south position with latitude The use of longitude to determine east or west position The measurement of latitude and longitude with degrees, minutes, and seconds Learning Outcomes .
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ Greenwich, England, is now the prime meridian for longitude and Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory, Greenwich, in London.
  • The Secret Voyage of Sir Francis Drake 2 February 2010 9:26 UTC www.reformation.org [Source type: FILTERED WITH BAYES]

[7] .Further improvement in gravitational models, such as the Earth Geopotential Model 1996 (EGM96), and a dramatic increase in the number of ground stations from only four to over 500, as well as the use of time based GPS caused a small additional shift before it reached its present position.^ Remember, the meridian was laid down in a time before GPS when all they had was the stars and clocks that suffered heavy gains and losses.
  • Where is the prime meridian? - PDA street forums 2 February 2010 9:26 UTC www.pdastreet.com [Source type: FILTERED WITH BAYES]

^ When you turn on the GPS unit, it will take some time for enough information from the satellite to be processed before your position is "fixed" or known.
  • WEB-LAB Module 1 2 February 2010 9:26 UTC cas.umkc.edu [Source type: FILTERED WITH BAYES]

^ The GPS receiver uses this information to calculate the time differences and thus distance to each satellite.
  • WEB-LAB Module 1 2 February 2010 9:26 UTC cas.umkc.edu [Source type: FILTERED WITH BAYES]

.The International Hydrographic Organization adopted an early version in 1983 for all nautical charts.^ Maritime Provinces--Maps--Early works to 1800; Nautical charts--Maritime Provinces--Early works to 1800 .
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]

^ Mapsend BlueNav Charts – This provides detailed nautical charts, and is available in American and European versions.
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

^ Newfoundland and Labrador--Maps--Early works to 1800; Nautical charts--Newfoundland and Labrador--Early works to 1800 .
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]
  • Memorial University of Newfoundland DAI : Search Results 2 February 2010 9:26 UTC collections.mun.ca [Source type: FILTERED WITH BAYES]

[8] .It was adopted for air navigation by the International Civil Aviation Organization on 3 March 1989.[9] Because tectonic plates slowly move over the surface of the Earth, most countries have adopted a version of the IRM for their maps that is fixed relative to their own tectonic plate as it existed at the beginning of a specific year, such as the North American Datum 1983 (NAD83), the European Terrestrial Reference Frame 1989 (ETRF89), and the Geocentric Datum of Australia 1994 (GDA94).^ Tectonic plates don't move that fast!
  • Where is the prime meridian? - PDA street forums 2 February 2010 9:26 UTC www.pdastreet.com [Source type: FILTERED WITH BAYES]

^ Longitude measures the west-east position of locations on the Earth's surface relative to a circular arc called the Prime Meridian ( Figure 2b-2 ).

^ Most maps allow us to specify the location of points on the Earth's surface using a coordinate system.

.Versions fixed to a tectonic plate differ from the global version by at most a few centimetres.^ Railway managers desire that the time used in their service shall be either precisely the same as that used by the public, or shall differ from it at as few points as possible, and then by the most readily calculated differences.
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

.However, the IRM is not fixed to any point on Earth.^ However, these points on the Earth are located in spatially different spots from the geographic North and South Pole.

.Instead, all points on the European portion of the Eurasian plate, including the Royal Observatory, are slowly moving northeast about 2.5 cm per year relative to it.^ About 60 new plates are added every year.
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

^ But the main attraction point is, of course, the hill with the Royal Observatory, on which there is the famous starting point of the prime meridian.
  • Boat Trip to Greenwich, London Docklands, Visit of Greenwich Park, Queen's House, Prime Meridian in the Royal Observatory, Millennium Dome 2 February 2010 9:26 UTC www.urlaube.info [Source type: FILTERED WITH BAYES]

^ That is where all longitude is measured from, and historically the location of the Royal Observatory where ships would check their chronometers.
  • Greenwich and World Time Zones 2 February 2010 9:26 UTC www.coe.ilstu.edu [Source type: News]

.This IRM is the weighted average in the least squares sense of the reference meridians of the hundreds of ground stations contributing to the IERS network, including GPS stations, Satellite Laser Ranging (SLR) stations, Lunar Laser Ranging (LLR) stations, and the highly accurate Very Long Baseline Interferometry (VLBI) stations.^ Geodetic measurements using satellites requires very accurate range computations.
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ The prime meridian is in the ground lined up, with the eye piece, and it is very near the icon on the map, but the gps read W000.00.045!
  • Where is the prime meridian? - PDA street forums 2 February 2010 9:26 UTC www.pdastreet.com [Source type: FILTERED WITH BAYES]

^ These systems consist of two parts: a GPS receiver and a network of many satellites.

[10] .The coordinates of all of these stations are adjusted annually until there is no net rotation relative to the major tectonic plates.^ The fact that there's no hollywood adaptation of these guys is just criminal.
  • What would you like to see adapted into a movie, and why? | Hollywood | Cracked.com Forums 2 February 2010 9:26 UTC www.cracked.com [Source type: FILTERED WITH BAYES]

^ There are several ground stations in the US which pick up the GPS signals and calculate these correction factors.
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

^ If you can pick up a WAAS signal, are relatively close to a ground station, and are in the open (no overhead obstructions), then WAAS may improve accuracy.
  • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

.If Earth had only two hemispherical plates moving relative to each other around any axis from that intersecting their centres to one intersecting their junction, the longitudes (around any other rotation axis) of any two stations diametrically opposite each other must move in opposite directions by the same amount.^ Axis of rotation – An imaginary line around which the earth rotates.
  • Maps101--Advanced Glossary 2 February 2010 9:26 UTC www.maps101.com [Source type: FILTERED WITH BAYES]

^ The duration of one rotation of the earth on its axis, with respect to the moon.
  • Dictionary of Technical Terms for Aerospace Use - L 2 February 2010 9:26 UTC er.jsc.nasa.gov [Source type: Reference]

^ The most widely accepted prime meridian is based on the Bureau International de l'Heure (BIH) Zero Meridian : Defined by the longitudes of many BIH stations around the world..
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

.Universal Time is notionally based on the WGS84 meridian.^ The adoption of the universal day or any system of time-reckoning [Pg 138] based upon infrequent—such as the great quadrant—meridians, to be used by transportation lines collaterally with local time, is, therefore, practically impossible.
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

^ The much more famous meridian, which is now used as the base point for all the world’s time zones, was defined by George Airy.
  • Greenwich prime meridian - Google Sightseeing 2 February 2010 9:26 UTC googlesightseeing.com [Source type: General]

^ Finally, it was decided to hold an international conference to settle differences of opinion on the basic issues associated with time and a universal prime meridian.
  • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

.However, the standard international time UTC can differ from the mean observed time on the meridian by up to 0.9 second (equivalent to about 260 metres at Greenwich), because of changes in the Earth's rotation.^ Earth's Prime Meridian has changed several times.
  • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

^ Local mean time at the Greenwich meridian is called Greenwich mean time, or universal time.
  • Dictionary of Technical Terms for Aerospace Use - L 2 February 2010 9:26 UTC er.jsc.nasa.gov [Source type: Reference]

^ Standard times are the mean solar times of the closest standard meridians, which are displaced in units if 15° from Greenwich.

.Leap seconds are inserted periodically to keep UTC close to Earth's angular position relative to the Sun — mean solar time.^ Time is the same throughout each zone and differs from the international basis of legal and scientific time, Greenwich Mean Time (GMT) or Coordinated Universal Time (UTC), by an integral number of hours; minutes and seconds are the same.

^ We speak of solar, astronomical, nautical, and civil time, of apparent and mean time.
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

^ Longitude measures the west-east position of locations on the Earth's surface relative to a circular arc called the Prime Meridian ( Figure 2b-2 ).


United Kingdom Ordnance Survey Zero Meridian

.The zero meridian used by the Ordnance Survey (OSGB36 datum) is about six metres to the west of the Airy meridian marked at Greenwich.^ I suppose as time zero the meridian of Greenwich.
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

^ I believe it was one of the decieding factors in the international agreement to use Greenwich in the beginning, when we went from a meridian in every capital city to just one.
  • Greenwich prime meridian - Google Sightseeing 2 February 2010 9:26 UTC googlesightseeing.com [Source type: General]

^ "It is proper to count longitude from the meridian of Greenwich in one direction from west to east."
  • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

.When the first Ordnance Survey map was published in 1801, the official Prime Meridian of Great Britain was the one established by the third Astronomer Royal, James Bradley.^ The prime meridian is the one at which longitude is 0 degrees.
  • http://www.goworldtravel.com/ex/aspx/articleGuid.95778af3-2569-48c8-bfd3-494534bfacf0/xe/article.htm 2 February 2010 9:26 UTC www.goworldtravel.com [Source type: News]

^ Documents published by Prime Meridian Corp.

^ The prime meridian in this map passes through Toledo in Spain.
  • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

.When Airy's new Prime Meridian ('new' by virtue of Sir George Airy's instrument being placed in a room next to that housing James Bradley's instrument) superseded it fifty years later in 1851, the Ordnance Survey simply continued to use Bradley's.^ What is the prime meridian used for?
  • prime meridian Facts, information, pictures | Encyclopedia.com articles about prime meridian 2 February 2010 9:26 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

^ Here, you can stand in both hemispheres at the same time by placing your feet on either side of the prime meridian.
  • http://www.goworldtravel.com/ex/aspx/articleGuid.95778af3-2569-48c8-bfd3-494534bfacf0/xe/article.htm 2 February 2010 9:26 UTC www.goworldtravel.com [Source type: News]

^ Forbes also included two new statistics to its annual survey: job projections and the ratio of subprime mortgages to loan originations for the last three years.

[11]

Other planetary bodies

.Like on earth, Prime Meridians must be arbitrarily defined.^ The most widely accepted prime meridian is based on the Bureau International de l'Heure (BIH) Zero Meridian : Defined by the longitudes of many BIH stations around the world..
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ Longitude measures the west-east position of locations on the Earth's surface relative to a circular arc called the Prime Meridian ( Figure 2b-2 ).

^ On other bodies the prime meridian is defined with respect to a known surface feature, such as a small crater.
  • prime meridian Facts, information, pictures | Encyclopedia.com articles about prime meridian 2 February 2010 9:26 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

.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.^ Use the Define method of IPrimeMeridianEdit to set the properties of a prime meridian.
  • PrimeMeridian (ArcObjects Java API) 2 February 2010 9:26 UTC resources.esri.com [Source type: Reference]

^ Since the placement of a prime meridian is arbitrary, other countries have often used their own.
  • Unit 014 - Latitude and Longitude 2 February 2010 9:26 UTC www.ncgia.ucsb.edu [Source type: Reference]

^ At any given instant of time, any celestial object (e.g.
  • The Secret Voyage of Sir Francis Drake 2 February 2010 9:26 UTC www.reformation.org [Source type: FILTERED WITH BAYES]

The Prime Meridians of the following planetographic systems have been defined:
.
  • 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 is defined by the crater Airy-0.
  • The Prime Meridian of Venus passes through the central peak in the crater Ariadne.^ The prime meridian in this map passes through Toledo in Spain.
    • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

    ^ The prime meridian in this map passes through the Canary Islands.
    • A multitude of prime meridian. - Mercator Plancius Ortelius 2 February 2010 9:26 UTC www.findingnz.co.nz [Source type: FILTERED WITH BAYES]

    ^ The prime meridian on Earth passes through the transit circle established by G. B. Airy at Greenwich, and defines the zero of terrestrial longitude.
    • prime meridian Facts, information, pictures | Encyclopedia.com articles about prime meridian 2 February 2010 9:26 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

    [12]
  • .
  • Two different heliographic coordinate systems are used on the Sun.^ From time to time these protocols change, so at any given time different worlds may have different coordinate systems.
    • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

    ^ Two simple changes would bring the lunar coordinate system up to modern standards, improve utility, increase efficiency, and reduce errors.
    • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

    ^ Figure 2b-1 : A grid coordinate system defines the location of points from the distance traveled along two perpendicular axes from some stated origin.

    .The first is the Carrington heliographic coordinate system.^ In this coordinate system, the value associated with the X-axis is given first, following by the value assigned from the Y-axis.

    ^ According to the reference system, the bright green quadrilateral has the grid reference 29V (note that in this system west-east coordinate is given first, followed by the south-north coordinate).

    .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 Richard Christopher Carrington started his observations of sunspots.^ The prime meridian of this moon passes through the mean sub-Earth direction.

    ^ It is also the location where the prime meridian passes through.
    • http://www.goworldtravel.com/ex/aspx/articleGuid.95778af3-2569-48c8-bfd3-494534bfacf0/xe/article.htm 2 February 2010 9:26 UTC www.goworldtravel.com [Source type: News]

    ^ The starting point of this system is the meridian of Greenwich.
    • The Project Gutenberg eBook of International ConferenceHeld at Washingtonfor the Purpose of Fixinga Prime Meridiananda Universal Day. 2 February 2010 9:26 UTC www.gutenberg.org [Source type: Original source]

    [13] .The second is the Stonyhurst heliographic coordinates system.
  • Jupiter has several coordinate systems because different latitudes rotate at different rates.^ From time to time these protocols change, so at any given time different worlds may have different coordinate systems.
    • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

    ^ The meridian has several pre-programmed coordinate systems.
    • Magellan Meridian FAQ 2 February 2010 9:26 UTC www.mtgc.org [Source type: General]

    ^ Michael Stennecken of Mnster, Germany, discovered that published coordinates of lunar landing sites disagreed, because different lunar coordinate systems were used.
    • OL5 Space and Robotics 2002 - [TITLE] 2 February 2010 9:26 UTC www.oregonl5.org [Source type: FILTERED WITH BAYES]

    [14] .Scientific Astronomer uses System II coordinates, based on the mean atmospheric rotation of the north and south Equatorial belts.^ In this system, north and south are the dominant directions.

    ^ Most maps allow us to specify the location of points on the Earth's surface using a coordinate system.

    ^ Geographic grid – Spherical coordinate system used for finding locations on the earth's surface.
    • Maps101--Advanced Glossary 2 February 2010 9:26 UTC www.maps101.com [Source type: FILTERED WITH BAYES]

    System III coordinates use Jupiter's magnetic field.
  • Titan, like the Earth's moon, always has the same face towards Saturn, and so that face is 0 longitude.

See also

References

  1. ^ Atlas do Brazil, 1909, by Barão Homem de Mello e Francisco Homem de Mello, published in Rio de Janeiro by F. Briguiet & Cia.
  2. ^ 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.
  3. ^ The meridian of Ptolemy's Almagest.
  4. ^ Wilcomb E. Washburn, "The Canary Islands and the Question of the Prime Meridian: The Search for Precision in the Measurement of the Earth"
  5. ^ Maimonides, Hilchot Kiddush Hachodesh 11:17, 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.
  6. ^ History of the Prime Meridian -Past and Present
  7. ^ G. Gebel and B. Matthews, "Navigation at the Prime Meridian", Navigation: Journal of the Institute of Navigation (Washington, DC) 18/2 (Summer 1971) 141-146.
  8. ^ A manual on the technical aspects of the United Nations Convention on the Law of the Sea - 1982PDF (4.89 MB) Section 2.4.4
  9. ^ WGS 84 Implementation Manual page i, 1998
  10. ^ IERS Conventions (2003): Conventional Terrestrial Reference System and FramePDF (419 KB)
  11. ^ Charles Jennings; "Greenwich: The Place Where Days Begin and End", Little, Brown; 1999; p. 181
  12. ^ "USGS Astrogeology: Rotation and pole position for the Sun and planets (IAU WGCCRE)". http://astrogeology.usgs.gov/Projects/WGCCRE/constants/iau2000_table1.html. Retrieved 22 October 2009. 
  13. ^ "Carrington heliographic coordinates". http://www.encyclopedia.com/doc/1O80-Carringtonheligrphccrdnts.html. 
  14. ^ "Planetographic Coordinates". http://documents.wolfram.com/applications/astronomer/AdditionalInformation/PlanetographicCoordinates.html. Retrieved 2009-06-19. 

External links


Simple English

[[File:|180px|thumb|right|Location of the Prime Meridian]]

The Prime Meridian is the meridian (line of longitude) that goes through the Royal Greenwich Observatory in London it is also known as the International Meridian or Greenwich Meridian.

Other pages



Citable sentences

Up to date as of December 16, 2010

Here are sentences from other pages on Prime Meridian, which are similar to those in the above article.








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