Royal Observatory, Greenwich – Wikipedia

Flamsteed House in 1824 Royal Observatory, Greenwich c. 1902 as depicted on a postcard The Royal Observatory, Greenwich ( ROG ; [ 1 ] known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux ) is an observatory situated on a hill in Greenwich Park in south east London, overlooking the River Thames to the north. It played a major character in the history of astronomy and navigation, and because the Prime meridian passes through it, it gave its name to Greenwich Mean Time, the precursor to nowadays ‘s Coordinated Universal Time ( UTC ). The ROG has the IAU observatory code of 000, the beginning in the list. [ 2 ] ROG, the National Maritime Museum, the Queen ‘s House and the clipper embark Cutty Sark are jointly designated Royal Museums Greenwich. [ 1 ] The observatory was commissioned in 1675 by King Charles II, with the foundation garment stone being laid on 10 August. The web site was chosen by Sir Christopher Wren, a former Savilian Professor of Astronomy ; as Greenwich Park was a imperial estate of the realm, no fresh land needed to be bought. [ 3 ] At that clock the king besides created the place of Astronomer Royal, to serve as the conductor of the observatory and to “ apply himself with the most claim care and application to the correct of the tables of the motions of the heavens, and the places of the specify stars, so as to find out the so a lot desired longitude of places for the perfect of the art of navigation. ” He appointed John Flamsteed as the beginning Astronomer Royal. The build up was completed in the summer of 1676. [ 4 ] The build was frequently called “ Flamsteed House ”, in reference book to its beginning resident. The scientific work of the observatory was relocated elsewhere in stages in the first gear one-half of the twentieth century, and the Greenwich site is now maintained about entirely as a museum, although the AMAT telescope became operational for astronomic inquiry in 2018 .

history [edit ]

chronology [edit ]

locate [edit ]

There had been meaning buildings on this domain since the reign of William I. [ 7 ] [ page needed ] Greenwich Palace, on the site of the contemporary Maritime Museum, was the birthplace of both Henry VIII and his daughters Mary I and Elizabeth I ; the Tudors used Greenwich Castle, which stood on the hilltop that the Observatory soon occupies, as a hunt lodge. Greenwich Castle was reportedly a favored seat for Henry VIII to firm his mistresses, so that he could well travel from the Palace to see them. [ 8 ] [ page needed ] In 1676 the main building of the lookout, now known as Flamsteed House, was completed on Greenwich hill. [ 9 ]

institution [edit ]

Royal Observatory, Greenwich telescope and tree The establishment of a Royal Observatory was proposed in 1674 by Sir Jonas Moore who, in his function as Surveyor-General of the Ordnance, persuaded King Charles II to create the observatory, with John Flamsteed installed as its conductor. [ 10 ] The Ordnance Office was given duty for building the Observatory, with Moore providing the winder instruments and equipment for the lookout at his own personal cost. Flamsteed House, the original separate of the Observatory, was designed by Sir Christopher Wren, credibly assisted by Robert Hooke, and was the first base purpose-built scientific inquiry facility in Britain. It was built for a price of £520 ( £20 over budget ; equivalent to £80,000 in 2020 ) out of largely recycle materials on the foundations of Duke Humphrey ‘s Tower, the harbinger of Greenwich Castle, which resulted in the alignment being 13 degrees away from true North, slightly to Flamsteed ‘s chagrin. [ citation needed ] 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 grimace, giving a time period of four seconds and an accuracy, then unparalleled, of seven seconds per day. [ citation needed ] The original observatory housed the astronomer royal, his adjunct and his syndicate a well as the scientific instruments to be used by Flamsteed in his work on stellar tables. Over prison term the mental hospital became a more conventional institution, thanks to its links to durable politics boards ( the Board of Ordnance and Board of Longitude ) 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. [ 11 ] By the by and by eighteenth hundred it incorporated extra responsibilities such as publishing the Nautical Almanac, advising politics on technical foul matters, disseminating time, making meteorologic and magnetic observations and undertaking astrophotography and spectroscopy. The physical locate [ 12 ] and the numbers of staff [ 13 ] increased all over clock as a result .

positional astronomy and leading charts [edit ]

The Airy Transit Circle, used for over a hundred ( 1851–1953 ) as the reference point when charting the heavens and determining times, therefore earning for it the epithet “ the center of time and space ” When the lookout was founded in 1675, one of the best star catalogues was Tycho Brahe ‘s 1000-star catalogue from 1598. [ 14 ] however, this catalog was not accurate enough to determine longitudes. [ 14 ] One of Flamsteed ‘s first orders of clientele was creating more accurate charts suitable for this purpose. [ 14 ] 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. [ 14 ] Bradley was the third base Astronomer Royal, and his tenure started in 1742. [ 15 ] In the early nineteenth century, the main positional devices were the Troughton Transit instrument and a mural set, but after George Biddell Airy took over as Astronomer Royal in 1835, he embarked on a plan to have better instruments at Greenwich observatory. [ 16 ] positional astronomy was one of the primary coil functions of Greenwich for the Admiralty. [ 17 ] The Astronomer Royal Airy was an advocate of this and the theodolite encircle instrument he had installed in 1851 was used for a century for positional astronomy. [ 17 ] One of the difficulties with positional astronomy, is accounting for the deflection of light through Earth ‘s atmosphere. [ 18 ] Sources of error include the preciseness of the instrumentality, and then there has to be accounting for precession, nutation, and aberrance. [ 19 ] Sources of error in the instrument have to be tracked down and accounted for to produced more accurate results. [ 16 ] The passage circle makes two measurements ; along with a clock, the time a star passed a certain point in the flip as the Earth rotates, and the vertical angle of the location of the headliner. [ 20 ] The instrument can be used to plot the locations of stars, or alternately, with an accurate ace chart, the time at the location of the instrument. [ 20 ]

1832 Transit of Mercury [edit ]

The Shuckburgh telescope of the Royal Observatory in London was used for the 1832 transit of Mercury. [ 21 ] It was equipped with a filar micrometer by Peter Dollond and was used to provide a report of the events as seen through the little refractor. [ 21 ] By observing the transit in combination with timing it and taking measures, a diameter for the planet was taken. [ 21 ] They besides reported the peculiar effects that they compared to pressing a coin into the Sun. [ 21 ] The perceiver remarked :

I afterwards observed, that immediately around the planet there was a dusky tint, making it appear as if, in a small degree sink below the sun ‘s surface ; ”Royal Astronomical Society, Vol II, No. 13[21]

Greenwich Meridian [edit ]

Laser projected from the observatory marking the Prime Meridian argumentation laser at night british astronomers have long used the Royal Observatory as a basis for measurement. Four separate meridians have passed through the buildings, defined by consecutive instruments. [ 22 ] The basis of longitude, the meridian that passes through the Airy transit encircle, first used in 1851, was adopted as the world ‘s Prime Meridian at the International Meridian Conference at Washington, D.C. on 22 October 1884 ( voting took locate on 13 October ). [ 23 ] Subsequently, nations across the global used it as their criterion for function and timekeeping. The Prime Meridian was marked by a boldness ( late replaced by stainless steel ) strip in the Observatory ‘s court once the buildings became a museum in 1960, and, since 16 December 1999, has been marked by a brawny greens laser shining union across the London night flip. Since the first base triangulation of Great Britain in the period 1783–1853, Ordnance Survey maps have been based on an earlier version of the Greenwich prime, defined by the theodolite instrumental role of James Bradley. When the Airy circle ( 5.79 meter to the east ) became the address for the acme, the remainder 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 prime was not 0° but 0°00’00.417 ” ( about 8 meter ) East. [ 24 ] Besides the change of the reference book line, imperfections of the review 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 ). [ 25 ] This old astronomic prime acme has been replaced by a more precise prime prime. When Greenwich was an active agent observatory, geographic coordinates were referred to a local anesthetic oblate spheroid called a datum known as a geoid, whose open close matched local hateful sea level. several datums were in use around the populace, all using different spheroids, because entail sea level undulates by equally much as 100 metres cosmopolitan. Modern geodetic mention systems, such as the World Geodetic System and the International Terrestrial Reference Frame, use a unmarried oblate spheroid, fixed to the Earth ‘s gravitational concentrate. The switch from respective local spheroids to one cosmopolitan spheroid caused all geographic coordinates to shift by many metres, sometimes american samoa a lot as respective hundred metres. The Prime Meridian of these modern reference systems, called IERS ( International Earth Rotation and Reference Systems Service ) Reference Meridian ( curtly called IRM ), is 102.5 metres east of the Greenwich astronomic meridian represented by the stainless steel comic strip, which is now 5.31 arcseconds West. The modern location of the Airy Transit is as the IRM is at 0 degree in longitude nowadays. [ 26 ] International time from the end of the nineteenth 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 lap and the IERS lineage :. [ 27 ]

Greenwich Mean Time [edit ]

One of the hyper-accurate timekeepers at the lookout 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 in 1935, but is placid normally referred to as GMT, though they are not identical. It is now calculated from observations of extra-galactic radio receiver sources. The observatory is noted as the home of the flower meridian and Greenwich mean time. [ 28 ] A cardinal musical instrument for determining time was the Airy Transit Circle, which was used chiefly from 1851 to 1938. [ 29 ] It was agreed in 1884 that the “ meridian cable 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. [ 29 ] The time is determined by marking the meter a asterisk of known location would pass through the aimpoint of the telescope. [ 29 ] In a reverse character, this type of instrument was besides used for making star charts. [ 29 ] The stars whose put was known precisely enough for being used for time determination, were called “ clock stars. ” [ 29 ]

greenwich Time Ball [edit ]

The prison term musket ball is the bolshevik musket ball on a position – when it drops a sealed time is signalled. This allowed clocks to be set from afar with great accuracy, particularly the chronometers of ships on the River Thames below, prior to sailing. The lookout would inaugural determine the prison term by stellar observations. The bolshevik time musket ball of Greenwich was established in 1833, and is noted as a public time signal. [ 30 ] The meter ball in modern times is normally in a lower position, then starting at 12:55 phase modulation, the ball begins to rise, then at 12:58 it reaches the top ; at 1 phase modulation the ball drops. [ 30 ] To help mariners at the port and others in course of sight of the lookout to synchronise their clocks to GMT, Astronomer Royal John Pond installed a very visible time ball that drops precisely at 1 prime minister ( 13:00 ) every day atop the lookout in 1833. Initially it was dropped by an operator ; from 1852 it was released mechanically via an electric urge from the Shepherd Master Clock. [ 31 ] The ball is hush dropped daily at 13:00 ( GMT in winter, BST in summer ). [ 32 ] The original time ball system was built by Messrs Maudslay and Field, and cost £180. [ 33 ] The five-foot diameter ball was made of wood and leather. [ 33 ] In the original ball system, it was hoisted by a rope up from the Octagon room, and there was catch at the crown to hold it. [ 33 ] This could then be triggered by pass, while observing the time on an astronomic month clock, that was regulated to the mean solar time. [ 33 ] By dropping the ball, the public, mariners, and clock makers could then get a time bespeak by viewing it from afar. [ 33 ] The musket ball drop would be repeated at 2 autopsy besides if possible. [ 33 ] The reason why 12 noon was not chosen was because astronomers at the lookout would record when the Sun crossed the acme at that time on that day. [ 34 ] In rare occasions where the ball could get stuck due to icing or snow, and if the wind was excessively high it would not be dropped. [ 33 ] [ 35 ] In 1852, it was established to distribute a time signal by the telegraph wires besides. [ 33 ] The clock testis was highly popular with the public, chronometers, railways, mariners, and there was a petition to have another time ball established in Southampton besides. [ 33 ]

1890s [edit ]

Dome of the Great Equatorial Building overlooking Greenwich Park 21st-century horizon of the Altazimuth Pavilion

The 1890s marked the summation 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 raw dome had to be bigger ; frankincense the celebrated “ onion dome ” that expands beyond the diameter of the gun enclosure was established. For the tricentenary, it was revitalized with a fibre-glass attic ; the old one make 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 methamphetamine. [ 36 ] [ page needed ] The modern dome was made by T. Cooke and Sons. [ 36 ] [ page needed ] This replaced a smaller drum-shaped dome. [ 36 ] The Lassell two-foot reflector was a celebrated metal-mirror telescope that had been used to discover the Moons Triton and Hyperion. [ 37 ] It was donated to the lookout in the 1880s, but was taken down in the 1890s. [ 37 ] The 1890s besides saw the structure of the Altazimuth Pavilion, completed in 1896 and designed by William Crisp. [ 38 ] In 1898 the Christie Enclosure was established to firm sensitive charismatic instruments that had been disrupted by the habit of iron at the main facility. [ 39 ] The Observatory undergo an try fail on 15 February 1894. This was possibly the first “ external terrorist ” incident in Britain. [ 40 ] The bomb calorimeter was unintentionally detonated while being held by 26-year-old french anarchist Martial Bourdin in Greenwich Park, near the Observatory build. Bourdin died about 30 minutes late. It is not known why he chose the lookout, or whether the detonation was intended to occur elsewhere. The novelist Joseph Conrad used the incident in his novel The Secret Agent. [ 41 ]

early twentieth century [edit ]

[42][43] Standard lengths on the rampart of the Royal Observatory, Greenwich, London – 1 yard ( 3 feet ), 2 feet, 1 foundation, 6 inches ( 1/2-foot ), and 3 inches. The legal separation of the inwardly faces of the marks is exact at an ambient temperature of 60 °F ( 16 °C ) and a gat of the decline meter, resting on the pins, will fit snugly between them. For major parts of the twentieth century, the Royal Greenwich Observatory was not at Greenwich, because it moved to Herstmonceux 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 and Meteorological Departments, and the Magnetic Observatory moved to Abinger in Surrey. Prior to this, the lookout had had to insist that the electric tramway in the vicinity could not use an earth return for the grip current. [ 44 ] After the attack of World War II in 1939, many departments were temporarily evacuated out of range of german bombers, to Abinger, Bradford on Avon, Bristol, [ 45 ] and Bath, [ 46 ] and activities in Greenwich were reduced to the bare minimum. On 15 October 1940, during the Blitz, the Courtyard gates were destroyed by a lead fail hit. The rampart above the Gate Clock collapsed, and the clock ‘s dial was damaged. The damage was repaired after the war. [ 47 ]

The Royal Observatory at Herstmonceux [edit ]

After the second gear World War, in 1947, the decision was made to move the Royal Observatory to Herstmonceux Castle [ 48 ] and 320 adjacent acres ( 1.3 km2 ), 70 km south-southeast of Greenwich near Hailsham in East Sussex, due to light pollution 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. [ 49 ] The largest telescope at Greenwich at that time, the Yapp telescope 36-inch reflecting telescope, was moved out to Herstmonceux in 1958. [ 50 ] There it was reconstructed in Dome B of the facility. [ 50 ] There it was used for astronomy in the 1960s, 1970s, and 1980s. It was left behind at Herstmonceux in 1990 in its attic when the organization moved once again. [ 49 ] The tricentenary 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 honor of the lionize inventor of the newtonian reflecting telescope. Some two decades of exploitation led to the commission of the Isaac Newton Telescope at Herstmonceux. It proved then successful that the cloudy weather was felt to be a bottleneck to its productiveness, 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. [ 51 ] The telescope was the biggest telescope by aperture in the british Isles. [ 52 ] It was moved to Roque de los Muchachos Observatory in Spain ‘s Canary Islands in 1979. In 1990 the RGO moved to Cambridge. [ 53 ] At Herstmonceux, the castle grounds became the dwelling of the International Study Centre of Queen ‘s University, Kingston, Canada and The Observatory Science Centre, [ 54 ] which is operated by an educational charity Science Project .
Former Royal Greenwich Observatory, Herstmonceux, East Sussex The Observatory Science Centre opened in April 1995. [ 55 ] Some of the remaining telescopes, which were left behind in the move, have public observation events as share of operations of the center. [ 55 ] The centre has established itself as a notice tourist and education attraction in its own mighty, featuring many old lookout items as exhibits. [ 56 ] It was getting 60,000 visitors per class in the early twenty-first hundred. [ 55 ]

The Royal Observatory at Cambridge [edit ]

Greenwich House at Cambridge In 1990 the Royal Observatory moved from Herstmonceux to a new locate at Cambridge, adjacent to the University ‘s Institute of Astronomy, where it occupied Greenwich House just to the north of the Cambridge Observatory. 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 potent British-owned telescopes ( such as the Isaac Newton Telescope, the Anglo-Dutch Jacobus Kapteyn Telescope, and the William Herschel Telescope ) on the Canary Islands and Hawaii. [ 57 ] After abandoning a design to privatise the RGO and the Royal Observatory Edinburgh, the Particle Physics and Astronomy Research Council ( PPARC ) as the RGO ‘s fund consistency made the decision to close the mental hospital and the Cambridge web site by 1998. [ 57 ] When the RGO was closed as an initiation, the HM Nautical Almanac Office transferred to the Rutherford Appleton Laboratory ( Harwell Science and Innovation Campus, Chilton, Oxfordshire ), while other work went to the UK Astronomy Technology Centre in Edinburgh. The old observatory site at Greenwich returned to its original identify – 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. [ 58 ]

Greenwich locate returns to active use [edit ]

The Queen ‘s House ( center left ) at Greenwich, with the Royal Observatory on the horizon behind, in 2017. In 2018 the Annie Maunder Astrographic Telescope ( AMAT ) was installed at the ROG in Greenwich. [ 59 ] [ 60 ] AMAT is a bunch of four separate instruments, to be used for astronomic research ; it had achieved inaugural light by June 2018, and contains : [ 61 ]

• 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 nebulae at different optical wavelengths.
• A general-purpose telescope.

The telescopes and the works at the web 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, [ 62 ] from which the multi-purpose telescope is controlled by a computer organization. [ 62 ]

magnetic observations [edit ]

The Magnetic Pavilion, 1900 The first magnetic observation was taken in 1680 by the first Astronomer Royal, John Flamsteed, using a charismatic needle from the Royal Society. [ 63 ] The irregular and third base Astronomers Royal, Edmond Halley and then James Bradley, besides took some magnetic measurements during their tenure. [ 63 ] In the nineteenth hundred George Airy established the Magnetical and Meteorological Department. [ 63 ] The first Magnetic House was built adjacent to the lookout but by 1900 a second, about 300–400 metres from the main observatory, was built to reduce magnetic interference. [ 64 ] Both houses were made of non-magnetic materials. [ 64 ] The older build 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. [ 64 ] A new Magnetograph House was besides completed by 1914. [ 64 ] One of the extra events that occurred in the cogitation of magnetism was when François Arago and Alexander von Humboldt took magnetic observations at Greenwich in 1822. [ 65 ] In 1825 Arago won the Copley Gold Medal for this research [ 65 ] ( see besides Arago ‘s rotations ) .

Observatory museum [edit ]

Tourists flock to the Observatory museum, 2009 The lookout buildings at Greenwich became a museum of astronomic and navigational tools, which is separate of the Royal Museums Greenwich. [ 66 ] celebrated exhibits include John Harrison ‘s initiate chronometer, known as H4, for which he received a big reward from the Board of Longitude, and his three earlier marine timekeepers ; all four are the property of the Ministry of Defence. many extra horological artefacts are displayed, documenting the history of preciseness timekeeping for navigational and astronomic purposes, including the mid-20th-century Russian-made F.M. Fedchenko clock ( the most accurate pendulum clock ever built in multiple copies ). It besides houses the astronomic instruments used to make meridian observations and the 28-inch equatorial Grubb refracting telescope of 1893, the largest of its kind in the UK. The Shepherd Clock outside the lookout gate is an early on model of an electric slave clock. [ citation needed ] In 1997 the lookout site was getting 400,000 visitors per year. [ 67 ] In February 2005 a £16 million renovation comprising a modern planetarium and extra display galleries and educational facilities was started ; the ROG reopened on 25 May 2007 with the newfangled 120-seat Peter Harrison Planetarium. [ 68 ] For a year between 2016 and 2017 the Museum reported 2.41 million visitors. [ 69 ]

locate [edit ]

See besides [edit ]

References [edit ]

further read [edit ]

• 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. ISBN 0-85066-093-9; Vol. 2. Recent history (1836–1975), by A.J. Meadows. ISBN 0-85066-094-7; Vol. 3. The buildings and instruments by Derek Howse. ISBN 0-85066-095-5)