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48-620: Swavesey is a village lying on the Prime Meridian in Cambridgeshire, England, with a population of 2,463. The village is situated 9 miles to the north west of Cambridge and 3 miles south east of St Ives . Listed as Suauesye in the Domesday Book , the name Swavesey means "landing place (or island) of a man named Swaef". Swavesey, forming a historical parish of 3982 acres on the border with Huntingdonshire , lies on

96-456: A brass strip in the courtyard, now replaced by stainless steel, and since 16 December 1999, it has been marked by a powerful green laser shining north across the London night sky. The Global Positioning System (GPS) receivers show that the marking strip for the prime meridian at Greenwich is not exactly at zero degrees, zero minutes, and zero seconds but at approximately 5.3 seconds of arc to

144-445: A localized gravity effect due to vertical deflection ; thus, no systematic rotation of global longitudes occurred between the former astronomical system and the current geodetic system. Before the establishment of a common meridian, most maritime countries established their own prime meridian, usually passing through the country in question. In 1721, Great Britain established its own meridian passing through an early transit circle at

192-431: A narrow clay ridge rising to 18 metres above sea level at one time surrounded by fenland. The village was of importance during the early Middle Ages as the centre of a large 11th-century estate. A castle was built here in the late 11th or early 12th century, though is believed to have been derelict by 1200. Swavesey served as a port and subsequent market town and was fortified at the end of the 12th century. An alien priory

240-460: A point along the meridian at a given longitude is given by its latitude , measured in angular degrees north or south of the Equator . On a Mercator projection or on a Gall-Peters projection , each meridian is perpendicular to all circles of latitude . Assuming a spherical Earth , a meridian is a great semicircle on Earth's surface. Adopting instead a spheroidal or ellipsoid model of Earth,

288-585: A result, a Conference was held in 1884, in Washington, D.C. Twenty-six countries were present at the International Meridian Conference to vote on an international prime meridian. Ultimately the outcome was as follows: there would be only one prime meridian, the prime meridian was to cross and pass at Greenwich (which was the 0°), there would be two longitude direction up to 180° (east being plus and west being minus), there will be

336-516: A universal day, and the day begins at the mean midnight of the initial meridian. There were two main reasons for this. The first was that the USA had already chosen Greenwich as the basis for its own national time zone system. The second was that in the late 19th century, 72% of the world's commerce depended on sea-charts which used Greenwich as the Prime Meridian. The recommendation was based on

384-416: Is the magnetic declination , which is relevant for navigating with a compass. Navigators were able to use the azimuth (the horizontal angle or direction of a compass bearing) of the rising and setting Sun to measure the magnetic variation (difference between magnetic and true north). The true meridian is the chord that goes from one pole to the other, passing through the observer, and is contrasted with

432-453: Is the moment when a celestial object passes the meridian of longitude of the observer. At this point, the celestial object is at its highest point. When the Sun passes two times an altitude while rising and setting can be averaged to give the time of meridian passage. Navigators utilized the Sun's declination and the Sun's altitude at local meridian passage, in order to calculate their latitude with

480-537: Is the standard meridian for Eastern European Time . Since the adoption of time zones – as opposed to local mean time or solar time – in the late 19th century and early 20th century, most countries have adopted the standard time of one of the 24 meridians closest to their geographical position, as decided by the International Meridian Conference in 1884. Although, a few time zones are offset by an additional 30 or 45 minutes, such as in

528-519: The Equator a few degrees west of the later meridian and Accra , Ghana . The plane of the prime meridian is parallel to the local gravity vector at the Airy transit circle ( 51°28′40.1″N 0°0′5.3″W  /  51.477806°N 0.001472°W  / 51.477806; -0.001472  ( Airy Transit ) ) of the Greenwich observatory. The prime meridian was therefore long symbolised by

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576-729: The IERS Reference Meridian , is based on the Greenwich meridian, but differs slightly from it. This prime meridian (at the time, one of many ) was first established by Sir George Airy in 1851, and by 1884, over two-thirds of all ships and tonnage used it as the reference meridian on their charts and maps. In October of that year, at the invitation of the President of the United States , 41 delegates from 25 nations met in Washington, D.C. , United States, for

624-472: The International Meridian Conference . This conference selected the meridian passing through Greenwich as the world standard prime meridian due to its popularity. However, France abstained from the vote, and French maps continued to use the Paris meridian for several decades. In the 18th century, London lexicographer Malachy Postlethwayt published his African maps showing the "Meridian of London" intersecting

672-493: The Sun crosses the celestial meridian at the same time. The same Latin stem gives rise to the terms a.m. (ante meridiem) and p.m. (post meridiem) used to disambiguate hours of the day when utilizing the 12-hour clock . Because of a growing international economy, there was a demand for a set international prime meridian to make it easier for worldwide traveling which would, in turn, enhance international trading across countries. As

720-514: The Via Devana , the old Roman road, that now forms the A14 . Farming is the main industry in and around Swavesey, although most residents commute to work. There were three pubs listed in the village in 1765, and eight by the early 19th century. By the late 19th century, this number had risen to 16, but had fallen back to eight by 1912, and only three by 1960. Since then the only public house in

768-477: The apparent centre of gravity of Earth still points to (aligns with) the modern celestial meridian (the intersection of the prime meridian plane with the celestial sphere), it does not pass through Earth's rotation axis. As a result of this, the ITRF zero meridian, defined by a plane passing through Earth's rotation axis, is 102.478 metres to the east of the prime meridian. A 2015 analysis by Malys et al. shows

816-589: The "intended meridian" are based on a failure of understanding. The explanation by Malys et al . on the other hand is more studied and correct. The Greenwich meridian passes through eight countries in Europe and Africa from north to south: It also passes through Antarctica , only touching Queen Maud Land , a territorial claim of Norway , on its way from the North Pole to the South Pole . It crosses

864-509: The 19th century there were still concerns of the prime meridian. Multiple locations for the geographical meridian meant that there was inconsistency, because each country had their own guidelines for where the prime meridian was located. The term meridian comes from the Latin meridies , meaning "midday"; the subsolar point passes through a given meridian at solar noon , midway between the times of sunrise and sunset on that meridian. Likewise,

912-577: The Airy transit circle. This became the United Kingdom's meridian in 1851. For all practical purposes of the period, the changes as the meridian was moved went unnoticed. Transit instruments are installed to be perpendicular to the local level (which is a plane perpendicular to a plumb line). In 1884, the International Meridian Conference took place in Washington, D.C. to establish an internationally-recognised single meridian. The meridian chosen

960-499: The Greenwich prime meridian and the plane passing through Earth's rotation axis on the ITRF zero meridian are effectively parallel. Claims, such as that on the BBC website, that the gap between astronomical and geodetic coordinates means that any measurements of transit time across the IRTF zero meridian will occur precisely 0.352 seconds (or 0.353 sidereal seconds) before the transit across

1008-764: The Strict and Particular Baptist Church in Middle Watch, and the Bethel Baptist Church, also in Middle Watch. The railway line from Cambridge to St Ives , which passed through Swavesey, was opened in 1847 and closed in 1970, but has reopened as the Cambridgeshire Guided Busway . The parish's north border is formed by the River Great Ouse , formerly an important transport link. The parish's south west border runs along

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1056-638: The antimeridian, forms the other half of a circle with the one through Greenwich, and is at 180° longitude near the International Date Line (with land mass and island deviations for boundary reasons). The meridians from Greenwich (0°) west to the antimeridian (180°) define the Western Hemisphere and the meridians from Greenwich (0°) east to the antimeridian (180°) define the Eastern Hemisphere . Most maps show

1104-412: The argument that naming Greenwich as Longitude 0º would be of advantage to the largest number of people. Toward the ending of the 12th century there were two main locations that were acknowledged as the geographic location of the meridian, France and Britain. These two locations often conflicted and a settlement was reached only after there was an International Meridian Conference held, in which Greenwich

1152-489: The evenings and a myriad of extracurricular after school clubs. Prime Meridian (Greenwich) The Greenwich meridian is a prime meridian , a geographical reference line that passes through the Royal Observatory , Greenwich , in London , England. From 1884 to 1974, the Greenwich meridian was the international standard prime meridian, used worldwide for timekeeping and navigation. The modern standard,

1200-558: The following four centuries. A Unitarian chapel was built in 1831 on the corner of School Lane and High Street, and the congregation moved to a new Baptist chapel in 1869. The original Unitarian chapel was bought by a group of Methodists and served as their place of worship until it was converted into a bungalow in 1934. Today, there are three places of worship in Swavesey: St Andrew's parish church in Station Road,

1248-459: The formula. Latitude = (90° – noon altitude + declination) The declination of major stars are their angles north and south from the celestial equator. The meridian passage will not occur exactly at 12 hours because of the Earth orbit excentricity (see Equation of time ). A standard meridian is a meridian used for determining standard time . For instance, the 30th meridian east ( UTC+02:00 )

1296-439: The lines of longitude. The position of the prime meridian has changed a few times throughout history, mainly due to the transit observatory being built next door to the previous one (to maintain the service to shipping). Such changes had no significant practical effect. Historically, the average error in the determination of longitude was much larger than the change in position. The adoption of World Geodetic System 84 " (WGS84) as

1344-410: The magnetic south and north poles and can be taken as the horizontal component of magnetic force lines along the surface of the Earth. Therefore, a compass needle will be parallel to the magnetic meridian. However, a compass needle will not be steady in the magnetic meridian, because of the longitude from east to west being complete geodesic . The angle between the magnetic and the true meridian

1392-489: The magnetic meridian in order to have a more qualitative, intuitive, and abstract function. He used the true meridian since his compass varied by a few degrees. There were some variations. When he noted the sight line for the True Meridian from his family's house to the depot, he could check the declination of his compass before and after surveying throughout the day. He noted this variation down. The meridian passage

1440-432: The magnetic meridian, which goes through the magnetic poles and the observer. The true meridian can be found by careful astronomical observations, and the magnetic meridian is simply parallel to the compass needle. The arithmetic difference between the true and magnetic meridian is called the magnetic declination , which is important for the calibration of compasses. Henry D. Thoreau classified this true meridian versus

1488-418: The maritime exclusive economic zones of: Meridian (geography) In geography and geodesy , a meridian is the locus connecting points of equal longitude , which is the angle (in degrees or other units ) east or west of a given prime meridian (currently, the IERS Reference Meridian ). In other words, it is a coordinate line for longitudes, a line of longitude . The position of

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1536-429: The meridian is half of a north-south great ellipse . The length of a meridian is twice the length of an Earth quadrant , equal to 20,003.93 km (12,429.87 mi) on a modern ellipsoid ( WGS 84 ). The first prime meridian was set by Eratosthenes in 200 BC. This prime meridian was used to provide measurement of the earth, but had many problems because of the lack of latitude measurement. Many years later around

1584-427: The newly established Royal Observatory at Greenwich. The meridian was moved around 10 metres or so east on three occasions as transit circles with newer and better instruments were built, on each occasion next door to the existing one. This was to allow uninterrupted observation during each new construction. The final meridian was established as an imaginary line from the North Pole to the South Pole passing through

1632-416: The offset between the former and the latter can be explained by this deflection of the vertical alone; other possible sources of the offset that have been proposed in the past are smaller than the current uncertainty in the deflection of the vertical, locally. The astronomical longitude of the Greenwich prime meridian was found to be 0.19″ ± 0.47″ E, i.e. the plane defined by the local vertical on

1680-519: The positioning system has moved the geodetic prime meridian 102.478 metres east of its last astronomic position (measured at Greenwich). The position of the current geodetic prime meridian is not identified at all by any kind of sign or marking at Greenwich (as the older astronomic position was), but can be located using a GPS receiver. It was in the best interests of the nations to agree to one standard meridian to benefit their fast growing economy and production. The disorganized system they had before

1728-415: The shape of Earth, modified for a particular zone; a published ellipsoid would be a good base line for measurements. The difference between the direction of a plumb line or vertical, and a line perpendicular to the surface of the ellipsoid of revolution – a normal to said ellipsoid – at a particular observatory, is the deflection of the vertical. When the Airy transit circle

1776-540: The universal day was going to be the mean solar day. They agreed that the days would begin at midnight and the universal day would not impact the use of local time. A report was submitted to the "Transactions of the Royal Society of Canada", dated 10 May 1894; on the "Unification of the Astronomical, Civil and Nautical Days"; which stated that: The magnetic meridian is an equivalent imaginary line connecting

1824-524: The vertical on a large scale. One might expect that plumb lines set up in various locations, if extended downward, would all pass through a single point, the centre of Earth, but this is not the case, primarily due to Earth being an ellipsoid , not a sphere. The downward extended plumb lines don't even all intersect the rotation axis of Earth; this much smaller effect is due to the uneven distribution of Earth's mass. To make computations feasible, scientists defined ellipsoids of revolution, more closely emulating

1872-603: The village centre has been the White Horse Inn, open since at least 1765, and adjacent to the village post office and shop. Notable former pubs include the Rose and Crown, on the corner of Boxworth End and Rose and Crown Road, which was open by 1765 but closed in the 1880s. The Black Horse on the corner of High Street and Black Horse Lane served from around 1777 until 1910. The Swan, (later the Swan with Two Necks), on Station Road

1920-492: The village. The village contains one primary school, Swavesey Primary School, which claims to be the only school in the United Kingdom to lie on the meridian . Swavesey Village College is a secondary school , which opened in 1958. The school provides secondary education for surrounding villages, including Over , Bar Hill , Longstanton , and Fenstanton , and uses a vertical tutor system . As with other village colleges , Swavesey's institution also provides adult education in

1968-631: The west of the meridian (meaning that the meridian appears to be 102 metres east). In the past, this offset has been attributed to the establishment of reference meridians for space-based location systems such as WGS-84 (which the GPS relies on) or to the fact that errors gradually crept into the International Time Bureau timekeeping process. The actual reason for the discrepancy is that the difference between precise GNSS coordinates and astronomically determined coordinates everywhere remains

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2016-523: Was awarded to Alan la Zouche , lord of Swavesey manor, by the start of the 14th century. The present parish church in Swavesey, dedicated to St Andrew since the 11th century, has a double aisle aspect to its nave . The east window in the Lady Chapel contains a 1967 Tree of Jesse by Francis Skeat . The present building has parts dating from the 11th century, but was substantially improved over

2064-642: Was built, a mercury basin was used to align the telescope to the perpendicular. Thus the circle was aligned with the local vertical or plumb line, which is deflected slightly from the normal, or line perpendicular, to the reference ellipsoid used to define geodetic latitude and longitude in the International Terrestrial Reference Frame (which is nearly the same as the WGS84 system used by the GPS ). While Airy's local vertical, set by

2112-758: Was founded in Swavesey shortly after the Norman Conquest , possibly replacing a Saxon minster . Roman pottery has been found in the parish. The village motto is "Steadfast in Work and Play". There was already a church in Swavesey at the time of the Norman Conquest, possibly a minster , when Alan, Count of Richmond , granted it to the Abbey of St Sergius and St Bacchus in Angers , France. The Abbey founded an alien priory there by 1086, but Swavesey Priory

2160-563: Was not sufficient for their increasing mobility. The coach services in England had erratic timing before the GWT. United States and Canada were also improving their railroad system and needed a standard time as well. With a standard meridian, stage coach and trains were able to be more efficient. The argument of which meridian is more scientific was set aside in order to find the most convenient for practical reasons. They were also able to agree that

2208-557: Was open from around 1777 to 1917. The Blue Bell was active from the late 18th century until around the Second World War, and the George and Dragon also opened in the late 18th century and closed in the first years of the 20th century. The village's post office opened in the 1850s. Swavesey has a village magazine called "The Meridian", and holds a biennial village festival. The MG Owners' Club has its UK headquarters just outside

2256-409: Was recognized as the 0° location. The meridian through Greenwich (inside Greenwich Park) , England, called the Prime Meridian , was set at zero degrees of longitude, while other meridians were defined by the angle at the center of the Earth between where it and the prime meridian cross the equator. As there are 360 degrees in a circle, the meridian on the opposite side of the Earth from Greenwich,

2304-399: Was that which passed through the Airy transit circle at Greenwich, and it became the prime meridian of the world for a century. In 1984 it was superseded in that role by the IERS Reference Meridian which, at this latitude, runs about 102 metres to the east of the Greenwich meridian. At around the time of the 1884 conference, scientists were making measurements to determine the deflection of

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