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The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to
Herstmonceux Herstmonceux ( , ; ) is a village and civil parish in the Wealden District of East Sussex, England, which includes Herstmonceux Castle. The Herstmonceux Medieval Festival is held annually in August. History The name comes from Anglo-Saxon ...
) is an observatory situated on a hill in Greenwich Park in south east London, overlooking the
River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, se ...
to the north. It played a major role in the history of
astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
and
navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation ...
, and because the
Prime Meridian A prime meridian is an arbitrary 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 ...
passes through it, it gave its name to
Greenwich Mean Time Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a c ...
, the precursor to today's
Coordinated Universal Time Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of Solar time#Mean solar time, mean solar time (such as Universal Time, UT1) at 0° longitude (at the I ...
(UTC). The ROG has the IAU observatory code of 000, the first in the list. ROG, the National Maritime Museum, the Queen's House and the
clipper ship A clipper was a type of mid-19th-century merchant sailing vessel, designed for speed. Clippers were generally narrow for their length, small by later 19th century standards, could carry limited bulk freight, and had a large total sail area. "Cl ...
'' Cutty Sark'' are collectively designated Royal Museums Greenwich. The observatory was commissioned in 1675 by King Charles II, with the foundation stone being laid on 10 August. The old hilltop site of
Greenwich Castle Greenwich Castle was a hunting lodge used during the reign of Henry VIII, located in Greenwich Park, in Greenwich, England. The Royal Observatory, Greenwich now stands on the site. Greenwich Castle was apparently a favourite place for Henry VIII ...
was chosen by
Sir Christopher Wren Sir Christopher Wren PRS FRS (; – ) was one of the most highly acclaimed English architects in history, as well as an anatomist, astronomer, geometer, and mathematician-physicist. He was accorded responsibility for rebuilding 52 churche ...
, a former
Savilian Professor of Astronomy The position of Savilian Professor of Astronomy was established at the University of Oxford in 1619. It was founded (at the same time as the Savilian Professorship of Geometry) by Sir Henry Savile, a mathematician and classical scholar who was ...
; as Greenwich Park was a royal estate, no new land needed to be bought. At that time the king also created the position of Astronomer Royal, to serve as the director of the observatory and to "apply himself with the most exact care and diligence to the rectifying of the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so much desired longitude of places for the perfecting of the art of navigation." He appointed John Flamsteed as the first Astronomer Royal. The building was completed in the summer of 1676. The building was often called "Flamsteed House", in reference to its first occupant. The scientific work of the observatory was relocated elsewhere in stages in the first half of the 20th century, and the Greenwich site is now maintained almost exclusively as a museum, although the AMAT telescope became operational for astronomical research in 2018.


History


Chronology

*1675 – 22 June, Royal Observatory founded by King Charles II. *1675 – 10 August, construction began. *1714 Longitude Act established the
Board of Longitude The Commissioners for the Discovery of the Longitude at Sea, or more popularly Board of Longitude, was a British government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding lon ...
and Longitude rewards. The Astronomer Royal was, until the Board was dissolved in 1828, always an ex officio Commissioner of Longitude. *1767 The fifth Astronomer Royal Nevil Maskelyne began publication of '' The Nautical Almanac'', based on observations made at the Observatory. *1818 Oversight of the Royal Observatory was transferred from the
Board of Ordnance The Board of Ordnance was a British government body. Established in the Tudor period, it had its headquarters in the Tower of London. Its primary responsibilities were 'to act as custodian of the lands, depots and forts required for the defence o ...
to the Board of Admiralty; at that time the observatory was charged with maintaining the Royal Navy's
marine chronometer A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation. It is used to determine longitude by comparing Greenwich Mean Time (GMT), or in the mode ...
s. *1833 Daily time signals began, marked by dropping a time ball. *1838 –
Sheepshanks equatorial Sheepshanks equatorial was a 6.7 inch (170 mm) aperture refracting telescope installed in 1838 at the Royal Observatory in Greenwich. The telescope was donated to the observatory by the astronomer Richard Sheepshanks. The telescope had a ...
, a 6.7 inch (170 mm) aperture
refracting telescope A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses an ...
installed. *1893 – The 28-inch Great refractor installed. *1899 The New Physical Observatory (now known as the South Building) was completed. *1924 Hourly time signals (
Greenwich Time Signal The Greenwich Time Signal (GTS), popularly known as the pips, is a series of six short tones (or "pips") broadcast at one-second intervals by many BBC Radio stations. The pips were introduced in 1924 and have been generated by the BBC since 1990 ...
) from the Royal Observatory were first broadcast on 5 February. *1931 Yapp telescope ordered. *1948 Office of the Astronomer Royal was moved to
Herstmonceux Herstmonceux ( , ; ) is a village and civil parish in the Wealden District of East Sussex, England, which includes Herstmonceux Castle. The Herstmonceux Medieval Festival is held annually in August. History The name comes from Anglo-Saxon ...
in
East Sussex East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
. *1957 Royal Observatory completed its move to Herstmonceux, becoming the Royal Greenwich Observatory (RGO). The Greenwich site was renamed the Old Royal Observatory. *1990 RGO moved to
Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...
. *1998 RGO closed. Greenwich site was returned to its original name, the Royal Observatory, Greenwich, and was made part of the National Maritime Museum. *2011 The Greenwich museums, including the ROG, became collectively the Royal Museums Greenwich.


Site

There had been significant buildings on this land since the reign of William I. Greenwich Palace, on the site of the present-day Maritime Museum, was the birthplace of both
Henry VIII Henry VIII (28 June 149128 January 1547) was King of England from 22 April 1509 until his death in 1547. Henry is best known for his six marriages, and for his efforts to have his first marriage (to Catherine of Aragon) annulled. His disa ...
and his daughters Mary I and
Elizabeth I Elizabeth I (7 September 153324 March 1603) was Queen of England and Ireland from 17 November 1558 until her death in 1603. Elizabeth was the last of the five House of Tudor monarchs and is sometimes referred to as the "Virgin Queen". Eli ...
;
the Tudors ''The Tudors'' is a historical fiction television series set primarily in 16th-century England, created and written by Michael Hirst and produced for the American premium cable television channel Showtime. The series was a collaboration among ...
used
Greenwich Castle Greenwich Castle was a hunting lodge used during the reign of Henry VIII, located in Greenwich Park, in Greenwich, England. The Royal Observatory, Greenwich now stands on the site. Greenwich Castle was apparently a favourite place for Henry VIII ...
, which stood on the hilltop that the Observatory presently occupies, as a hunting lodge. Greenwich Castle was reportedly a favourite place for Henry VIII to house his mistresses, so that he could easily travel from the Palace to see them. In 1676 the main building of the observatory, now known as Flamsteed House, was completed on Greenwich hill.


Establishment

The establishment of a Royal Observatory was proposed in 1674 by Sir Jonas Moore who, in his role as Surveyor-General of the Ordnance, persuaded King Charles II to create the observatory, with John Flamsteed installed as its director. The Ordnance Office was given responsibility for building the Observatory, with Moore providing the key instruments and equipment for the observatory at his own personal cost. Flamsteed House, the original part of the Observatory, was designed by Sir
Christopher Wren Sir Christopher Wren PRS FRS (; – ) was one of the most highly acclaimed English architects in history, as well as an anatomist, astronomer, geometer, and mathematician-physicist. He was accorded responsibility for rebuilding 52 church ...
, probably assisted by Robert Hooke, and was the first purpose-built scientific research facility in Britain. It was built for a cost of £520 (£20 over budget; ) out of largely recycled materials on the foundations of Duke Humphrey's Tower, the forerunner of Greenwich Castle, which resulted in the alignment being 13 degrees away from true North, somewhat to Flamsteed's chagrin. Moore donated two clocks, built by Thomas Tompion, which were installed in the 20 foot high Octagon Room, the principal room of the building. They were of unusual design, each with a pendulum 13 feet (3.96 metres) in length mounted above the clock face, giving a period of four seconds and an accuracy, then unparalleled, of seven seconds per day. The original observatory housed the astronomer royal, his assistant and his family as well as the scientific instruments to be used by Flamsteed in his work on stellar tables. Over time the institution became a more established institution, thanks to its links to long-lasting government boards (the
Board of Ordnance The Board of Ordnance was a British government body. Established in the Tudor period, it had its headquarters in the Tower of London. Its primary responsibilities were 'to act as custodian of the lands, depots and forts required for the defence o ...
and
Board of Longitude The Commissioners for the Discovery of the Longitude at Sea, or more popularly Board of Longitude, was a British government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding lon ...
) and oversight by a Board of Visitors, founded in 1710 and made up of the President and Members of the council of the Royal Society. By the later 18th century it incorporated additional responsibilities such as publishing the '' Nautical Almanac'', advising government on technical matters, disseminating time, making meteorological and magnetic observations and undertaking astrophotography and spectroscopy. The physical site and the numbers of staff increased over time as a result.


Positional astronomy and star charts

When the observatory was founded in 1675, one of the best star catalogues was Tycho Brahe's 1000-star catalogue from 1598. However, this catalogue was not accurate enough to determine longitudes. One of Flamsteed's first orders of business was creating more accurate charts suitable for this purpose. One of the noted charts made at Greenwich was by the Astronomer Royal James Bradley, who between 1750 and 1762 charted sixty thousand stars, so accurately his catalogues were used even in the 1940s. Bradley was the third Astronomer Royal, and his tenure started in 1742. In the early 19th century, the main positional devices were the Troughton Transit instrument and a mural circle, but after George Biddell Airy took over as Astronomer Royal in 1835, he embarked on a plan to have better instruments at Greenwich observatory.
Positional astronomy Spherical astronomy, or positional astronomy, is a branch of observational astronomy used to locate astronomical objects on the celestial sphere, as seen at a particular date, time, and location on Earth. It relies on the mathematical methods of ...
was one of the primary functions of Greenwich for the Admiralty. The Astronomer Royal Airy was an advocate of this and the transit circle instrument he had installed in 1851 was used for a century for positional astronomy. One of the difficulties with positional astronomy, is accounting for the refraction of light through Earth's atmosphere. Sources of error include the precision of the instrumentation, and then there has to be accounting for precession, nutation, and aberration. Sources of error in the instrument have to be tracked down and accounted for to produced more accurate results. The transit circle makes two measurements; along with a clock, the time a star passed a certain point in the sky as the Earth rotates, and the vertical angle of the location of the star. The instrument can be used to plot the locations of stars, or alternately, with an accurate star chart, the time at the location of the instrument.


1832 Transit of Mercury

The
Shuckburgh telescope The Shuckburgh telescope or Shuckburgh equatorial refracting telescope was a diameter aperture telescope on an equatorial mount completed in 1791 for Sir George Shuckburgh (1751–1804) in Warwickshire, England, and built by British instrument ...
of the Royal Observatory in London was used for the 1832 transit of Mercury. It was equipped with a filar micrometer by Peter Dollond and was used to provide a report of the events as seen through the small refractor. By observing the transit in combination with timing it and taking measures, a diameter for the planet was taken. They also reported the peculiar effects that they compared to pressing a coin into the Sun. The observer remarked:


Greenwich Meridian

British astronomers have long used the Royal Observatory as a basis for measurement. Four separate meridians have passed through the buildings, defined by successive instruments. The basis of
longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...
, the meridian that passes through the Airy transit circle, first used in 1851, was adopted as the world's
Prime Meridian A prime meridian is an arbitrary 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 ...
at the International Meridian Conference at
Washington, DC ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morg ...
, on 22 October 1884 (voting took place on 13 October). Subsequently, nations across the world used it as their standard for mapping and timekeeping. The Prime Meridian was marked by a brass (later replaced by
stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's r ...
) strip in the Observatory's courtyard once the buildings became a museum in 1960, and, since 16 December 1999, has been marked by a powerful green
laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The ...
shining north across the London night sky. Since the first triangulation of Great Britain in the period 1783–1853,
Ordnance Survey Ordnance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose (see ordnance and surveying), which was to map Scotland in the wake of the Jacobite rising of 1745. There was a ...
maps have been based on an earlier version of the Greenwich meridian, defined by the transit instrument of James Bradley. When the Airy circle (5.79 m to the east) became the reference for the meridian, the difference resulting from the change was considered small enough to be neglected. When a new triangulation was done between 1936 and 1962, scientists determined that in the Ordnance Survey system the longitude of the international Greenwich meridian was not 0° but 0°00'00.417" (about 8 m) East. Besides the change of the reference line, imperfections of the surveying system added another discrepancy to the definition of the origin, so that the Bradley line itself is now 0°00'00.12" East of the Ordnance Survey Zero Meridian (about 2.3m). This old astronomical prime meridian has been replaced by a more precise prime meridian. When Greenwich was an active observatory, geographical coordinates were referred to a local
oblate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has ci ...
called a datum known as a geoid, whose surface closely matched local mean sea level. Several datums were in use around the world, all using different spheroids, because mean sea level undulates by as much as 100 metres worldwide. Modern geodetic reference systems, such as the
World Geodetic System The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also descr ...
and the
International Terrestrial Reference Frame The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface. This is done in much the same way that a physical standard might be descri ...
, use a single oblate spheroid, fixed to the Earth's gravitational centre. The shift from several local spheroids to one worldwide spheroid caused all geographical coordinates to shift by many metres, sometimes as much as several hundred metres. The Prime Meridian of these modern reference systems, called IERS (International Earth Rotation and Reference Systems Service) Reference Meridian (shortly called IRM), is 102.5 metres east of the Greenwich astronomical meridian represented by the stainless steel strip, which is now 5.31 
arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...
s West. The modern location of the Airy Transit is as the IRM is at 0 degree in longitude nowadays. International time from the end of the 19th century until UT1 was based on Simon Newcomb's equations, giving a mean sun about 0.18 seconds behind UT1 (the equivalent of 2.7 arcseconds) as of 2013; it coincided in 2013 with a meridian halfway between Airy's circle and the IERS origin: .


Greenwich Mean Time

Greenwich Mean Time (GMT) was until 1954 based on celestial observations made at Greenwich, and later on observations made at other observatories. GMT was formally renamed as
Universal Time Universal Time (UT or UT1) is a time standard based on Earth's rotation. While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle wit ...
in 1935, but is still commonly referred to as GMT, though they are not identical. It is now calculated from observations of extra-galactic radio sources. The observatory is noted as the home of the prime meridian and Greenwich mean time. A key instrument for determining time was the Airy Transit Circle, which was used primarily from 1851 to 1938. It was agreed in 1884 that the "meridian line marked by the cross-hairs in the Airy Transit Circle eyepiece would indicate 0° longitude and the start of the Universal Day" according to RMG. The time is determined by marking the time a star of known location would pass through the aimpoint of the telescope. In a reverse case, this type of instrument was also used for making star charts. The stars whose position was known precisely enough for being used for time determination, were called "clock stars."


Greenwich Time Ball

The red time ball of Greenwich was established in 1833, and is noted as a public time signal. The time ball in modern times is normally in a lowered position, then starting at 12:55pm, the ball begins to rise, then at 12:58 it reaches the top; at 1pm the ball drops. To help mariners at the port and others in line of sight of the observatory to synchronise their clocks to GMT, Astronomer Royal John Pond installed a very visible time ball that drops precisely at 1pm (13:00) every day atop the observatory in 1833. Initially it was dropped by an operator; from 1852 it was released automatically via an electric impulse from the Shepherd Master Clock. The ball is still dropped daily at 13:00 (GMT in winter, BST in summer). The original time ball system was built by Messrs Maudslay and Field, and cost £180. The five-foot diameter ball was made of wood and leather. In the original ball system, it was hoisted by a rope up from the Octagon room, and there was catch at the top to hold it. This could then be triggered by hand, while observing the time on an astronomical month clock, that was regulated to the
mean solar time Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day, based on the synodic rotation period. Two types of solar time are apparent solar time ( sundia ...
. By dropping the ball, the public, mariners, and clock makers could then get a time signal by viewing it from afar. The ball drop would be repeated at 2pm also if possible. The reason why 12 noon was not chosen was because astronomers at the observatory would record when the Sun crossed the meridian at that time on that day. In rare occasions where the ball could get stuck due to icing or snow, and if the wind was too high it would not be dropped. In 1852, it was established to distribute a time signal by the telegraph wires also. The time ball was extremely popular with the public, chronometers, railways, mariners, and there was a petition to have another time ball established in
Southampton Southampton () is a port city in the ceremonial county of Hampshire in southern England. It is located approximately south-west of London and west of Portsmouth. The city forms part of the South Hampshire built-up area, which also covers Po ...
also.


1890s

The 1890s marked the addition of a new larger refractor, the 28-inch Grubb in the Great Equatorial Dome. Because the new telescope was longer than the old Great refractor, the new dome had to be bigger; thus the famous "onion dome" that expands beyond the diameter of the turret was established. For the tricentennial, it was revitalized with a fibre-glass dome; the old one made of papier-mâché and iron had been taken down. The telescope was installed by 1893, with 28-inch diameter glass doublet lens made by Grubb from Chance of Birmingham glass. The new dome was made by T. Cooke and Sons. This replaced a smaller drum-shaped dome. The Lassell two-foot reflector was a famous metal-mirror telescope that had been used to discover the Moons
Triton Triton commonly refers to: * Triton (mythology), a Greek god * Triton (moon), a satellite of Neptune Triton may also refer to: Biology * Triton cockatoo, a parrot * Triton (gastropod), a group of sea snails * ''Triton'', a synonym of ''Triturus'' ...
and Hyperion. It was donated to the observatory in the 1880s, but was taken down in the 1890s. The 1890s also saw the construction of the Altazimuth Pavilion, completed in 1896 and designed by William Crisp. In 1898 the Christie Enclosure was established to house sensitive magnetic instruments that had been disrupted by the use of iron at the main facility. The Observatory underwent an attempted bombing on 15 February 1894. This was possibly the first "international terrorist" incident in Britain. The bomb was accidentally detonated while being held by 26-year-old French
anarchist Anarchism is a political philosophy and movement that is skeptical of all justifications for authority and seeks to abolish the institutions it claims maintain unnecessary coercion and hierarchy, typically including, though not necessar ...
Martial Bourdin in Greenwich Park, near the Observatory building. Bourdin died about 30 minutes later. It is not known why he chose the observatory, or whether the detonation was intended to occur elsewhere. The novelist Joseph Conrad used the incident in his 1907 novel ''
The Secret Agent ''The Secret Agent: A Simple Tale'' is a novel by Joseph Conrad, first published in 1907.. The story is set in London in 1886 and deals with Mr. Adolf Verloc and his work as a spy for an unnamed country (presumably Russia). ''The Secret Agent ...
''.


Early 20th century

For major parts of the twentieth century, the Royal Greenwich Observatory was not at Greenwich, because it moved to
Herstmonceux Herstmonceux ( , ; ) is a village and civil parish in the Wealden District of East Sussex, England, which includes Herstmonceux Castle. The Herstmonceux Medieval Festival is held annually in August. History The name comes from Anglo-Saxon ...
in Sussex in 1957. The last time that all departments were in Greenwich was 1924: in that year electrification of the railways affected the readings of the
Magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particl ...
and
Meteorological Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...
Departments, and the Magnetic Observatory moved to
Abinger Abinger is a large, well-wooded and mostly rural civil parish that lies between the settlements of Dorking, Shere and Ewhurst in the district of Mole Valley, Surrey, England. It adjoins Wotton Common on the same side of Leith Hill and incl ...
in Surrey. Prior to this, the observatory had had to insist that the electric trams in the vicinity could not use an earth return for the traction current. After the onset of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
in 1939, many departments were temporarily evacuated out of range of German bombers, to Abinger,
Bradford on Avon Bradford-on-Avon (sometimes Bradford on Avon or Bradford upon Avon) is a town and civil parish in west Wiltshire, England, near the border with Somerset, which had a population of 9,402 at the 2011 census. The town's canal, historic buildings, ...
,
Bristol Bristol () is a City status in the United Kingdom, city, Ceremonial counties of England, ceremonial county and unitary authority in England. Situated on the River Avon, Bristol, River Avon, it is bordered by the ceremonial counties of Glouces ...
, and
Bath Bath may refer to: * Bathing, immersion in a fluid ** Bathtub, a large open container for water, in which a person may wash their body ** Public bathing, a public place where people bathe * Thermae, ancient Roman public bathing facilities Plac ...
, and activities in Greenwich were reduced to the bare minimum. On 15 October 1940, during
the Blitz The Blitz was a German bombing campaign against the United Kingdom in 1940 and 1941, during the Second World War. The term was first used by the British press and originated from the term , the German word meaning 'lightning war'. The Germa ...
, the Courtyard gates were destroyed by a direct bomb hit. The wall above the Gate Clock collapsed, and the clock's dial was damaged. The damage was repaired after the war.


The Royal Observatory at Herstmonceux

After the Second World War, in 1947, the decision was made to move the Royal Observatory to Herstmonceux Castle and 320 adjacent acres (1.3 km2), 70 km south-southeast of Greenwich near
Hailsham Hailsham is a town, a civil parish and the administrative centre of the Wealden district of East Sussex, England.OS Explorer map Eastbourne and Beachy Head Scale: 1:25 000. Publisher:Ordnance Survey – Southampton B2 edition. Publishing Da ...
in East Sussex, due to
light pollution Light pollution is the presence of unwanted, inappropriate, or excessive use of artificial lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting, during the day or night. Light po ...
in London. The Observatory was officially known as the ''Royal Greenwich Observatory, Herstmonceux''. Although the Astronomer Royal Harold Spencer Jones moved to the castle in 1948, the scientific staff did not move until the observatory buildings were completed, in 1957. Shortly thereafter, other previously dispersed departments were reintegrated at Herstmonceux, such as the Nautical Almanac Office, Chronometer Department, the library, and observing equipment. The largest telescope at Greenwich at that time, the Yapp telescope 36-inch reflector, was moved out to Herstmonceux in 1958. There it was reconstructed in Dome B of the facility. There it was used for astronomy in the 1960s, 1970s, and 1980s. It was left behind at Herstmonceux in 1990 in its dome when the organization moved once again. The tricentennial of Sir Isaac Newton had passed during the Second World War, delaying festivities. One of the ground-swells was to build a 'big better' telescope in honour of the celebrated inventor of the Newtonian reflecting telescope. Some two decades of development led to the commissioning of the Isaac Newton Telescope at Herstmonceux. It proved so successful that the cloudy weather was felt to be a bottleneck to its productivity, and plans were made to get it to a higher spot with better weather. On 1 December 1967, the Isaac Newton Telescope of the Royal Greenwich Observatory at Herstmonceux was inaugurated by Queen Elizabeth II. The telescope was the biggest telescope by aperture in the British Isles. It was moved to Roque de los Muchachos Observatory in Spain's
Canary Islands The Canary Islands (; es, :es:Canarias, Canarias, ), also known informally as the Canaries, are a Spanish Autonomous communities of Spain, autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to ...
in 1979. In 1990 the RGO moved to
Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...
. At Herstmonceux, the castle grounds became the home of the International Study Centre of Queen's University, Kingston, Canada, and The Observatory Science Centre, which is operated by an educational charity Science Project. The Observatory Science Centre opened in April 1995. Some of the remaining telescopes, which were left behind in the move, have public observation events as part of operations of the centre. The centre has established itself as a noted tourist and education attraction in its own right, featuring many old observatory items as exhibits. It was getting 60,000 visitors per year in the early 21st century.


The Royal Observatory at Cambridge

In 1990 the Royal Observatory moved from Herstmonceux to a new site at
Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...
, adjacent to the
University A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United Stat ...
's Institute of Astronomy, where it occupied Greenwich House just to the north of the
Cambridge Observatory Cambridge Observatory is an astronomical observatory at the University of Cambridge in the East of England. It was established in 1823 and is now part of the site of the Institute of Astronomy. The old Observatory building houses the Institute ...
. By now, the RGO's focus had moved from carrying out observations from the British Isles to providing technical support, acting as a conduit between scientists in British universities and the powerful British-owned telescopes (such as the Isaac Newton Telescope, the Anglo-Dutch
Jacobus Kapteyn Telescope The Jacobus Kapteyn Telescope or JKT is a 1-metre optical telescope named for the Dutch astronomer Jacobus Kapteyn (1851-1922) of the Isaac Newton Group of Telescopes at the Roque de los Muchachos Observatory on La Palma in the Canary Islands, ...
, and the
William Herschel Telescope The William Herschel Telescope (WHT) is a optical/near-infrared reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands, Spain. The telescope, which is named after William Hersc ...
) on the
Canary Islands The Canary Islands (; es, :es:Canarias, Canarias, ), also known informally as the Canaries, are a Spanish Autonomous communities of Spain, autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to ...
and
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
.Charles Arthur, ''A closed subject?''
The Independent, 10 June 1997 (accessed 12 November 2019)
After abandoning a plan to privatise the RGO and the
Royal Observatory Edinburgh The Royal Observatory, Edinburgh (ROE) is an astronomical institution located on Blackford Hill in Edinburgh. The site is owned by the Science and Technology Facilities Council (STFC). The ROE comprises the UK Astronomy Technology Centre (UK& ...
, the Particle Physics and Astronomy Research Council (PPARC) as the RGO's funding body made the decision to close the institution and the Cambridge site by 1998. When the RGO was closed as an institution, the HM Nautical Almanac Office transferred to the
Rutherford Appleton Laboratory The Rutherford Appleton Laboratory (RAL) is one of the national scientific research laboratories in the UK operated by the Science and Technology Facilities Council (STFC). It began as the Rutherford High Energy Laboratory, merged with the Atla ...
(
Harwell Science and Innovation Campus The Harwell Science and Innovation Campus is a 700-acre science and technology campus in Oxfordshire, England. Over 6,000 people work there in over 240 public and private sector organisations, working across sectors including Space, Clean Ener ...
, Chilton,
Oxfordshire Oxfordshire is a ceremonial and non-metropolitan county in the north west of South East England. It is a mainly rural county, with its largest settlement being the city of Oxford. The county is a centre of research and development, primaril ...
), while other work went to the UK Astronomy Technology Centre in Edinburgh. The old observatory site at Greenwich returned to its original name – the Royal Observatory, Greenwich – and was made part of the National Maritime Museum. In 2002 the UK joined the European Southern Observatory, building the VISTA infrared telescope at the Paranal Observatory as an in-kind contribution. The Astronomer Royal Martin Rees called PPARC "irresponsible" for how it handled the RGO.


Greenwich site returns to active use

In 2018 the Annie Maunder Astrographic Telescope (AMAT) was installed at the ROG in Greenwich. AMAT is a cluster of four separate instruments, to be used for astronomical research; it had achieved first light by June 2018, and contains: * A 14-inch reflector that can take high-resolution images of the sun, moon and planets. * An instrument dedicated to observing the sun. * An instrument with interchangeable filters to view distant
nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...
e at different optical wavelengths. * A general-purpose telescope. The telescopes and the works at the site required to operate them cost about £150,000, from grants, museum members and patrons, and public donations. The telescope was installed in the Altazimuth Pavilion, from which the multi-purpose telescope is controlled by a computer system.


Magnetic observations

The first magnetic observation was taken in 1680 by the first Astronomer Royal, John Flamsteed, using a magnetic needle from the Royal Society. The second and third Astronomers Royal, Edmond Halley and then James Bradley, also took some magnetic measurements during their tenure. In the 19th century George Airy established the Magnetical and Meteorological Department. The first Magnetic House was built next to the observatory but by 1900 a second, about 300–400 metres from the main observatory, was built to reduce magnetic interference. Both houses were made of non-magnetic materials. The older building was called the Magnet House, but iron added to buildings in the 1890s at the observatory was throwing off measurements, so the instruments were moved to the Magnetic Pavilion. A new Magnetograph House was also completed by 1914. One of the special events that occurred in the study of magnetism was when
François Arago Dominique François Jean Arago ( ca, Domènec Francesc Joan Aragó), known simply as François Arago (; Catalan: ''Francesc Aragó'', ; 26 February 17862 October 1853), was a French mathematician, physicist, astronomer, freemason, supporter of t ...
and
Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister ...
took magnetic observations at Greenwich in 1822. In 1825 Arago won the Copley Gold Medal for this research (see also Arago's rotations).


Observatory museum

The observatory buildings at Greenwich became a museum of astronomical and navigational tools, which is part of the Royal Museums Greenwich. Notable exhibits include
John Harrison John Harrison ( – 24 March 1776) was a self-educated English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea. Harrison's solution revo ...
's pioneering chronometer, known as H4, for which he received a large reward from the
Board of Longitude The Commissioners for the Discovery of the Longitude at Sea, or more popularly Board of Longitude, was a British government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding lon ...
, and his three earlier marine timekeepers; all four are the property of the
Ministry of Defence {{unsourced, date=February 2021 A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is an often-used name for the part of a government responsible for matters of defence, found in state ...
. Many additional horological artefacts are displayed, documenting the history of precision timekeeping for navigational and astronomical purposes, including the mid-20th-century Russian-made F.M. Fedchenko clock (the most accurate pendulum clock ever built in multiple copies). It also houses the astronomical instruments used to make meridian observations and the 28-inch equatorial Grubb
refracting telescope A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses an ...
of 1893, the largest of its kind in the UK. The Shepherd Clock outside the observatory gate is an early example of an electric slave clock. In 1997 the observatory site was getting 400,000 visitors per year. In February 2005 a £16 million redevelopment comprising a new
planetarium A planetarium ( planetariums or ''planetaria'') is a Theater (structure), theatre built primarily for presenting educational entertainment, educational and entertaining shows about astronomy and the night sky, or for training in celestial navi ...
and additional display galleries and educational facilities was started; the ROG reopened on 25 May 2007 with the new 120-seat Peter Harrison Planetarium. For a year between 2016 and 2017 the Museum reported 2.41 million visitors.


Site


See also

*
List of astronomical observatories This is a list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no longer in ...


References


Further reading

*''Greenwich Observatory: ... the Royal Observatory at Greenwich and Herstmonceux, 1675–1975''. London: Taylor & Francis, 1975 3v. (Vol. 1. ''Origins and early history (1675–1835)'', by Eric G. Forbes. ; Vol. 2. ''Recent history (1836–1975)'', by A.J. Meadows. ; Vol. 3. ''The buildings and instruments'' by Derek Howse. )


External links


Royal Museums Greenwich (RMG) Web site
– includes section on Royal Observatory Greenwich (ROG)
ROG on RMG Web siteOnline catalogue of the Royal Greenwich Observatory Archives (held at Cambridge University Library)"Where the Earth's surface begins—and ends"
''Popular Mechanics'', December 1930
HM Nautical Almanac OfficeAerial View of The Royal Observatory, Greenwich at Google Maps
* ttp://www.royalobservatorygreenwich.org/devblog/wp-content/uploads/2015/05/RGO-Herstmonceux-site-plan-c.1967.jpg Map of the Royal Greenwich Observatory at Herstmonceuxbr> A Personal History of the Royal Greenwich Observatory at Herstmonceux Castle, 1948–1990 by George Wilkins, a former staff memberThe Observatory Science CentreIsaac Newton Group of TelescopesA pictorial catalogue of meridian markers
{{Authority control Buildings and structures completed in 1676 Christopher Wren buildings in London Astronomical observatories in England Cultural and educational buildings in London Buildings and structures in the Royal Borough of Greenwich Education in the Royal Borough of Greenwich History of the Royal Borough of Greenwich Grade I listed buildings in the Royal Borough of Greenwich Grade I listed museum buildings Tourist attractions in London Horological museums in the United Kingdom Museums in the Royal Borough of Greenwich Science and technology in London 1676 establishments in England Greenwich Park Time balls