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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 consequence, it cannot be used to specify a particular time unless a context is given. The term 'GMT' is also used as one of the names for the time zone UTC+00:00 and, in UK law, is the basis for civil time in the United Kingdom. English speakers often use GMT as a synonym for Coordinated Universal Time (UTC). For navigation, it is considered equivalent to UT1 (the modern form of mean solar time at 0° longitude); but this meaning can differ from UTC by up to 0.9s. The term GMT should thus not be used for purposes that require precision. Because of Earth's uneven angular velocity in its elliptical orbit and its axial tilt, noon (12:00:00) GMT is rarely the exact moment the Sun crosses the Greenwich Meridian and reaches its highest point in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Mean Time
Local mean time (LMT) is a form of solar time that corrects the variations of Solar time#Apparent solar time, local apparent time, forming a uniform time scale at a specific longitude. This measurement of time was used for everyday use during the 19th century before time zones were introduced beginning in the late 19th century; it still has some uses in astronomy and navigation. Past use Local mean time was used from the early 19th century, when local solar time or sundial time was last used until standard time was adopted on various dates in the several countries. Each town or city kept its own Meridian (geography), meridian. This led to a situation where locations one degree of longitude apart had times four minutes apart. This became a problem in the mid 19th century when railways needed clocks that were synchronized between stations, at the same time as people needed to match their clock (or the church clock) to the time tables. Standard time means that the same time is used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenwich Meridian
The historic prime meridian or Greenwich meridian is a geographical reference line that passes through the Royal Observatory, Greenwich, Royal Observatory, Greenwich, in London, England. The modern IERS Reference Meridian widely used today is based on the Greenwich meridian, but differs slightly from it. This prime meridian (at the time, one of prime meridian, many) was first established by George Biddell Airy, Sir George Airy in 1851, and by 1884, over two-thirds of all ships and tonnage used it as the reference Meridian (geography), meridian on their Nautical chart, charts and maps. In October of that year, at the behest of President of the United States, US President Chester A. Arthur, 41 delegates from 25 nations met in Washington, D.C., United States, for the International Meridian Conference. This conference selected the meridian passing through Greenwich as the world standard prime meridian due to its popularity. However, France abstained from the vote, and French maps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 lambda (λ). Meridians are semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, England on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west. Because of the Earth's rotation, there is a close connection between longitude and time measurement. Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absolute measure of time allows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 world its successor Coordinated Universal Time (UTC), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval (and later aerial) navigation and enabling the Age of Discovery and Colonialism to accelerate. The term ''chronometer'' was coined from the Greek words '' χρόνος (chronos)'' (meaning time) and ''meter'' (meaning measure) in 1713 by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maritime Nation
A maritime nation is any nation that borders the sea and is dependent on its use for the majority of the following state activities: commerce and transport, war, to define a territorial boundary, or for any maritime activity (activities using the sea to convey or produce an end result). Historically, the term has been used to refer to a thalassocracy such as Carthage and Phoenicia but during the medieval period increasingly became associated with the Maritime Republics of Venice, Pisa, Genoa, Amalfi, Gaeta, Ancona and Ragusa Ragusa is the historical name of Dubrovnik. It may also refer to: Places Croatia * the Republic of Ragusa (or Republic of Dubrovnik), the maritime city-state of Ragusa * Cavtat (historically ' in Italian), a town in Dubrovnik-Neretva County, Cro ...G. Benvenuti - Le Repubbliche Marinare. Amalfi, Pisa, Genova, Manusia Kontlo Venezia - Newton & Compton editori, Roma 1989; Armando Lodolini, ''Le repubbliche del mare'', Biblioteca di storia patria, 1967, Roma. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenwich Clock
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 Meridian (0° longitude) and Greenwich Mean Time. The town became the site of a royal palace, the Palace of Placentia from the 15th century, and was the birthplace of many Tudors, including Henry VIII and Elizabeth I. The palace fell into disrepair during the English Civil War and was demolished to be replaced by the Royal Naval Hospital for Sailors, designed by Sir Christopher Wren and his assistant Nicholas Hawksmoor. These buildings became the Royal Naval College in 1873, and they remained a military education establishment until 1998 when they passed into the hands of the Greenwich Foundation. The historic rooms within these buildings remain open to the public; other buildings are used by University of Greenwich and Trinity Laban Con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle East Broadcasting Centre
MBC Group ( ar, مجموعة إم بي سي), is a Saudi media conglomerate based in the Middle East and North Africa region. Launched in London in 1991, the company moved to its headquarters to Dubai in 2002 then moved to Riyadh in 2022. MBC Group operates over 17 free-to-air satellite TV channels, and a video on demand service (Shahid). MBC was the first broadcaster to provide a satellite-based free-to-air 24-hour television broadcasting network across the Arab world. The Group's current chairman is Waleed bin Ibrahim Al Ibrahim. Sam Barnett returned as MBC Group CEO in December 2020 after a one-year departure. MBC's television arm, MBC TV, broadcasts via Eutelsat, Arabsat and Nilesat satellites. MBC has more than 1,800 staff. In recent years MBC has been hit with major rounds of financial cuts, leading to 150 layoffs and major production cuts. These cuts were driven in part due to advertising not covering production costs and the failure to acquire exclusive rights to the Sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Met Office
The Meteorological Office, abbreviated as the Met Office, is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy and is led by CEO Penelope Endersby, who took on the role as Chief Executive in December 2018 and is the first woman to do so. The Met Office makes meteorological predictions across all timescales from weather forecasts to climate change. History The Met Office was established on 1 August 1854 as a small department within the Board of Trade under Vice Admiral (Royal Navy), Vice Admiral Robert FitzRoy as a service to sailor, mariners. The loss of the passenger vessel, the Royal Charter (ship), ''Royal Charter'', and 459 lives off the coast of Anglesey in a violent storm in October 1859 led to the first gale warning service. FitzRoy established a network of 15 coastal stations from which visual gale warnings could be provided for ships at sea. The new electric tele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against France. The modern Royal Navy traces its origins to the early 16th century; the oldest of the UK's armed services, it is consequently known as the Senior Service. From the middle decades of the 17th century, and through the 18th century, the Royal Navy vied with the Dutch Navy and later with the French Navy for maritime supremacy. From the mid 18th century, it was the world's most powerful navy until the Second World War. The Royal Navy played a key part in establishing and defending the British Empire, and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superiority globally. Owing to this historical prominence, it is common, even among non-Britons, to ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BBC World Service
The BBC World Service is an international broadcasting, international broadcaster owned and operated by the BBC, with funding from the Government of the United Kingdom, British Government through the Foreign Secretary, Foreign Secretary's office. It is the world's largest external broadcaster in terms of reception area, language selection and audience reach. It broadcasts radio news, speech and discussions in more than 40 languages to many parts of the world on Analogue signal, analogue and Shortwave listening, digital shortwave platforms, internet streaming, podcasting, Satellite radio, satellite, Digital Audio Broadcasting, DAB, FM broadcasting, FM and Medium wave, MW relays. In 2015, the World Service reached an average of 210 million people a week (via TV, radio and online). In November 2016, the BBC announced that it would start broadcasting in additional languages including Amharic and Igbo language, Igbo, in its biggest expansion since the 1940s. "BBC World Servic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands within the British Isles. Northern Ireland shares a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is , with an estimated 2020 population of more than 67 million people. The United Kingdom has evolved from a series of annexations, unions and separations of constituent countries over several hundred years. The Treaty of Union between the Kingdom of England (which included Wales, annexed in 1542) and the Kingdom of Scotland in 170 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle (ERA, which serves as a modern replacement for Greenwich Mean Sidereal Time). UT1 is the same everywhere on Earth. UT1 is required to follow the relationship :ERA = 2π(0.7790572732640 + 1.00273781191135448'' · Tu'') radians where ''Tu'' = ( Julian UT1 date - 2451545.0). History Prior to the introduction of standard time, each municipality throughout the clock-using world set its official clock, if it had one, according to the local position of the Sun (see solar time). This served adequately until the introduction of rail travel in Britain, which made it possible to travel fast enough over long distances to require continuous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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