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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
An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...
situated on a hill in
Greenwich Park
Greenwich Park is a former hunting park in Greenwich and one of the largest single green spaces in south-east London. One of the Royal Parks of London, and the first to be enclosed (in 1433), it covers , and is part of the Greenwich World Herita ...
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 astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
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 c ...
passes through it, it gave its name to
Greenwich Mean Time
Greenwich Mean Time (GMT) is the Local mean time, mean solar time at the Royal Observatory, Greenwich, Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, i ...
, 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 mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used ...
(UTC). The ROG has the
IAU
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
observatory code of 000, the first in the list. ROG, the
National Maritime Museum
The National Maritime Museum (NMM) is a maritime museum in Greenwich, London. It is part of Royal Museums Greenwich, a network of museums in the Maritime Greenwich World Heritage Site. Like other publicly funded national museums in the United ...
, the
Queen's House
Queen's House is a former royal residence built between 1616 and 1635 near Greenwich Palace, a few miles down-river from the City of London and now in the London Borough of Greenwich. It presently forms a central focus of what is now the Old Ro ...
and the
clipper ship
A clipper was a type of mid-19th-century Merchant ship, merchant Sailing ship, 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 ...
''
Cutty Sark
''Cutty Sark'' is a British clipper ship. Built on the River Leven, Dumbarton, Scotland in 1869 for the Jock Willis Shipping Line, she was one of the last tea clippers to be built and one of the fastest, coming at the end of a long period of ...
'' are collectively designated
Royal Museums Greenwich
Royal Museums Greenwich is an organisation comprising four museums in Greenwich, east London, illustrated below. The Royal Museums Greenwich Foundation is a Private Limited Company by guarantee without share capital use of 'Limited' exemption, co ...
.
[
The observatory was commissioned in 1675 by King Charles II, with the ]foundation stone
The cornerstone (or foundation stone or setting stone) is the first stone set in the construction of a masonry foundation. All other stones will be set in reference to this stone, thus determining the position of the entire structure.
Over time ...
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 t ...
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 churches ...
, 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 Professor of Geometry, Savilian Professorship of Geometry) by Henry Savile (Bible translator), S ...
; as Greenwich Park
Greenwich Park is a former hunting park in Greenwich and one of the largest single green spaces in south-east London. One of the Royal Parks of London, and the first to be enclosed (in 1433), it covers , and is part of the Greenwich World Herita ...
was a royal estate, no new land needed to be bought. At that time the king also created the position of Astronomer Royal
Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834.
The post ...
, 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
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called ''Atlas Coe ...
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
The Longitude Act 1714 was an Act of Parliament of Great Britain passed in July 1714 at the end of the reign of Queen Anne. It established the Board of Longitude and offered monetary rewards (Longitude rewards) for anyone who could find a simple ...
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 longitude rewards were the system of inducement prizes offered by the British government for a simple and practical method for the precise determination of a ship's longitude at sea. The rewards, established through an Act of Parliament (t ...
. 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
Nevil Maskelyne (; 6 October 1732 – 9 February 1811) was the fifth British Astronomer Royal. He held the office from 1765 to 1811. He was the first person to scientifically measure the mass of the planet Earth. He created the ''British Nau ...
began publication of ''The Nautical Almanac
''The Nautical Almanac'' has been the familiar name for a series of official British almanacs published under various titles since the first issue of ''The Nautical Almanac and Astronomical Ephemeris'', for 1767: this was the first nautical alm ...
'', 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 ...
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 modern ...
s.
*1833 Daily time signals began, marked by dropping a time ball
A time ball or timeball is a time-signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators aboard ships offshore to verify the setting of their marine chron ...
.
*1838 – Sheepshanks equatorial
Sheepshanks equatorial was a 6.7 inch (170 mm) aperture refracting telescope installed in 1838 at the Royal Observatory, Greenwich, Royal Observatory in Greenwich. The telescope was donated to the observatory by the astronomer Richard Sheep ...
, 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 (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...
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 199 ...
) 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 Su ...
.
*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
The National Maritime Museum (NMM) is a maritime museum in Greenwich, London. It is part of Royal Museums Greenwich, a network of museums in the Maritime Greenwich World Heritage Site. Like other publicly funded national museums in the United ...
.
*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
Greenwich ( , ,) is a town in south-east London, England, within the ceremonial county of Greater London. It is situated east-southeast of Charing Cross.
Greenwich is notable for its maritime history and for giving its name to the Greenwich ...
, 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
Mary I (18 February 1516 – 17 November 1558), also known as Mary Tudor, and as "Bloody Mary" by her Protestant opponents, was Queen of England and Ireland from July 1553 and Queen of Spain from January 1556 until her death in 1558. Sh ...
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".
El ...
; 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 t ...
, 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
Sir Jonas Moore, FRS (1617–1679) was an English mathematician, surveyor, ordnance officer, and patron of astronomy. He took part in two of the most ambitious English civil engineering projects of the 17th century: draining the Great Level ...
who, in his role as Surveyor-General of the Ordnance
The Surveyor-General of the Ordnance was a subordinate of the Master-General of the Ordnance and a member of the Board of Ordnance, a British government body, from its constitution in 1597. Appointments to the post were made by the crown under Le ...
, 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 churches ...
, probably assisted by Robert Hooke
Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...
, 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
Thomas Tompion, FRS (1639–1713) was an English clockmaker, watchmaker and mechanician who is still regarded to this day as the "Father of English Clockmaking". Tompion's work includes some of the most historic and important clocks and watc ...
, 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 ...
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
A nautical almanac is a publication describing the positions of a selection of celestial bodies for the purpose of enabling navigators to use celestial navigation to determine the position of their ship while at sea. The Almanac specifies for ea ...
'', 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
Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was k ...
'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
James Bradley (1692–1762) was an English astronomer and priest who served as the third Astronomer Royal from 1742. He is best known for two fundamental discoveries in astronomy, the aberration of light (1725–1728), and the nutation of the ...
, 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
Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834.
The post ...
, and his tenure started in 1742.
In the early 19th century, the main positional devices were the Troughton Transit instrument and a mural circle
A mural is any piece of graphic artwork that is painted or applied directly to a wall, ceiling or other permanent substrate. Mural techniques include fresco, mosaic, graffiti and marouflage.
Word mural in art
The word ''mural'' is a Spanish ...
, but after George Biddell Airy
Sir George Biddell Airy (; 27 July 18012 January 1892) was an English mathematician and astronomer, and the seventh Astronomer Royal from 1835 to 1881. His many achievements include work on planetary orbits, measuring the mean density of the E ...
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
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...
, nutation
Nutation () is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism. In an appropriate reference frame ...
, 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
frameless, upright=0.5
A transit of Mercury across the Sun takes place when the planet Mercury passes directly between the Sun and a superior planet. During a transit, Mercury appears as a tiny black dot moving across the Sun as the planet obs ...
. It was equipped with a filar micrometer
A filar micrometer is a specialized eyepiece used in astronomical telescopes for astrometry measurements, in microscopes for specimen measurements, and in alignment and surveying telescopes for measuring angles and distances on nearby objects. Th ...
by Peter Dollond
Peter Dollond (24 February 1731 – 2 July 1820) was an English maker of optical instruments, the son of John Dollond. He is known for his successful optics business, and for the invention of the apochromat.
Biography
Dollond was born in Kensing ...
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 letter l ...
, the meridian that passes through the Airy
Airy may refer to:
* Sir George Biddell Airy (1801–1892), British Astronomer Royal from 1835 to 1881, for whom the following features, phenomena, and theories are named:
** Airy (lunar crater)
** Airy (Martian crater)
** Airy-0, a smaller crater ...
transit circle
The meridian circle is an instrument for timing of the passage of stars across the local meridian, an event known as a culmination, while at the same time measuring their angular distance from the nadir. These are special purpose telescopes mount ...
, 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 c ...
at the International Meridian Conference
The International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States, to determine a prime meridian for international use. The conference was held at the request of U.S. President Chester A. Art ...
at Washington, DC
)
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, 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 Morgan ...
, 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 corros ...
) 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 fir ...
shining north across the London night sky.
Since the first triangulation of Great Britain in the period 1783–1853, Ordnance Survey
, nativename_a =
, nativename_r =
, logo = Ordnance Survey 2015 Logo.svg
, logo_width = 240px
, logo_caption =
, seal =
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, picture_width =
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, di ...
maps have been based on an earlier version of the Greenwich meridian, defined by the transit instrument of James Bradley
James Bradley (1692–1762) was an English astronomer and priest who served as the third Astronomer Royal from 1742. He is best known for two fundamental discoveries in astronomy, the aberration of light (1725–1728), and the nutation of the ...
. 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 circ ...
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 descri ...
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 na ...
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
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 with ...
was based on Simon Newcomb
Simon Newcomb (March 12, 1835 – July 11, 1909) was a Canadian–American astronomer, applied mathematician, and autodidactic polymath. He served as Professor of Mathematics in the United States Navy and at Johns Hopkins University. Born in Nov ...
'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 with ...
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
A time ball or timeball is a time-signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators aboard ships offshore to verify the setting of their marine chron ...
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
John Pond FRS (1767 – 7 September 1836) was a renowned English astronomer who became the sixth Astronomer Royal, serving from 1811 to 1835.
Biography
Pond was born in London and, although the year of his birth is known, the records indica ...
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 (sundial ti ...
.
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
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
dome; the old one made of papier-mâché
upright=1.3, Mardi Gras papier-mâché masks, Haiti
upright=1.3, Papier-mâché Catrinas, traditional figures for day of the dead celebrations in Mexico
Papier-mâché (, ; , literally "chewed paper") is a composite material consisting of p ...
and iron had been taken down.
The telescope was installed by 1893, with 28-inch diameter glass doublet lens
In optics, a doublet is a type of lens made up of two simple lenses paired together. Such an arrangement allows more optical surfaces, thicknesses, and formulations, especially as the space between lenses may be considered an "element". With a ...
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 neces ...
Martial Bourdin
Martial Bourdin (1868 – 15 February 1894) was a French anarchist, who died on 15 February 1894 when chemical explosives that he was carrying prematurely detonated outside the Royal Observatory in Greenwich Park, London.
Although Bourdin sus ...
in Greenwich Park
Greenwich Park is a former hunting park in Greenwich and one of the largest single green spaces in south-east London. One of the Royal Parks of London, and the first to be enclosed (in 1433), it covers , and is part of the Greenwich World Herita ...
, 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
Joseph Conrad (born Józef Teodor Konrad Korzeniowski, ; 3 December 1857 – 3 August 1924) was a Poles in the United Kingdom#19th century, Polish-British novelist and short story writer. He is regarded as one of the greatest writers in t ...
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 particle ...
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 inclu ...
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 vast majority of the world's countries—including all of the great powers—forming two opposin ...
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, s ...
, Bristol
Bristol () is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire to the north and Somerset to the south. Bristol is the most populous city in ...
, 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
Herstmonceux Castle is a brick-built castle, dating from the 15th century, near Herstmonceux, East Sussex, England. It is one of the oldest significant brick buildings still standing in England. The castle was renowned for being one of the f ...
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 Dat ...
in East Sussex, due to light pollution
Light pollution is the presence of unwanted, inappropriate, or excessive use of artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting, during the day ...
in London. The Observatory was officially known as the ''Royal Greenwich Observatory, Herstmonceux''. Although the Astronomer Royal
Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834.
The post ...
Harold Spencer Jones
Sir Harold Spencer Jones KBE FRS FRSE PRAS (29 March 1890 – 3 November 1960) was an English astronomer. He became renowned as an authority on positional astronomy and served as the tenth Astronomer Royal for 23 years. Although born "Jon ...
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
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the great ...
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
The Isaac Newton Telescope or INT is a 2.54 m (100 in) optical telescope run by the Isaac Newton Group of Telescopes at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984.
Originally the INT was situated at Her ...
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
Roque de los Muchachos Observatory ( es, Observatorio del Roque de los Muchachos, ORM) is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, Spain. The observatory site is operated ...
in Spain's Canary Islands
The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
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 States, t ...
'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 o ...
. 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 Isaac Newton Telescope or INT is a 2.54 m (100 in) optical telescope run by the Isaac Newton Group of Telescopes at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984.
Originally the INT was situated at Her ...
, 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, Sp ...
, 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 Herschel, ...
) on the Canary Islands
The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
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?''](_blank)
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&nbs ...
, the Particle Physics and Astronomy Research Council
The Particle Physics and Astronomy Research Council (PPARC) was one of a number of research councils in the United Kingdom. It directed, coordinated and funded research in particle physics and astronomy for the people of the UK. Its head office w ...
(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
His Majesty's Nautical Almanac Office (HMNAO), now part of the United Kingdom Hydrographic Office, was established in 1832 on the site of the Royal Observatory, Greenwich (ROG), where ''The Nautical Almanac'' had been published since 1767. HMNAO ...
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 Atlas ...
(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, primarily ...
), while other work went to the UK Astronomy Technology Centre
The UK Astronomy Technology Centre (UK ATC) is based at the Royal Observatory in Edinburgh, Scotland, and is part of the Science and Technology Facilities Council.
The UK ATC designs, builds, develops, tests and manages major instrumentation ...
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
The National Maritime Museum (NMM) is a maritime museum in Greenwich, London. It is part of Royal Museums Greenwich, a network of museums in the Maritime Greenwich World Heritage Site. Like other publicly funded national museums in the United ...
.
In 2002 the UK joined the European Southern Observatory
The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...
, building the VISTA infrared telescope at the Paranal Observatory
Paranal Observatory is an astronomical observatory operated by the European Southern Observatory (ESO). It is located in the Atacama Desert of northern Chile on Cerro Paranal at altitude, south of Antofagasta. By total light-collecting area, it ...
as an in-kind contribution.
The Astronomer Royal Martin Rees
Martin John Rees, Baron Rees of Ludlow One or more of the preceding sentences incorporates text from the royalsociety.org website where: (born 23 June 1942) is a British cosmologist and astrophysicist. He is the fifteenth Astronomer Royal, ...
called PPARC "irresponsible" for how it handled the RGO.
Greenwich site returns to active use
In 2018 the Annie Maunder
Annie Scott Dill Maunder (née Russell) (14 April 1868 – 15 September 1947) was an Irish-British astronomer, who recorded the first evidence of the movement of sunspot emergence from the poles toward the equator over the sun's 11-year cycle. ...
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
Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.
From an observatory he constructed on Saint Helena in 1676–77, H ...
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, p ...
took magnetic observations at Greenwich in 1822. In 1825 Arago won the Copley Gold Medal for this research (see also Arago's rotations Arago's rotations is an observable magnetic phenomenon that involves the interactions between a magnetized needle and a moving metal disk. The effect was discovered by François Arago in 1824. At the time of their discovery, Arago's rotations were s ...
).
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 Carpentry, carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of calculating longitude while at s ...
's pioneering chronometer
A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and the ...
, 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 states ...
. 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 Grubb is a family name and may refer to the following:
* Armstead Otey Grubb (1903–1968), American educator and acting president of Lincoln University
* Catharina Elisabet Grubb (1721–1788), Finnish industrialist
* Curtis Grubb (c. 1730 – ...
refracting telescope
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...
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 theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation.
A dominant feature of most planetarium ...
and additional display galleries and educational facilities was started; the ROG reopened on 25 May 2007 with the new 120-seat Peter Harrison Planetarium
The Peter Harrison Planetarium is a 120-seat digital laser planetarium, situated in Greenwich Park, London and is part of the National Maritime Museum. It opened on 25 May 2007.
The planetarium uses Digistar 3 software with blue, red and green ...
.
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 site
Online 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 Office
Aerial 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 member
The Observatory Science Centre
Isaac Newton Group of Telescopes
A 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