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The FAA gradually assumed additional functions. The hijacking epidemic of the 1960s had already brought the agency into the field of civil aviation security. In response to the hijackings on September 11, 2001, this responsibility is now primarily taken by the Department of Homeland Security. The FAA became more involved with the environmental aspects of aviation in 1968 when it received the power to set aircraft noise standards. Legislation in 1970 gave the agency management of a new airport aid program and certain added responsibilities for airport safety. During the 1960s and 1970s, the FAA also started to regulate high altitude (over 500 feet) kite and balloon flying.
On the eve of America's entry into World War II, CAA began to extend its ATC responsibilities to takeoff and landing operations at airports. This expanded role eventually became permanent after the war. The application of radar to ATC helped controllers in their drive to keep abreast of the postwar boom in commercial air transportation. In 1946, meanwhile, Congress gave CAA the added task of administering the federal-aid airport program, the first peacetime program of financial assistance aimed exclusively at promoting development of the nation's civil airports.
By the mid-1970s, the agency had achieved a semi-automated air traffic control system using both radar and computer technology. This system required enhancement to keep pace with air traffic growth, however, especially after the Airline Deregulation Act of 1978 phased out the CAB's economic regulation of the airlines. A nationwide strike by the air traffic controllers union in 1981 forced temporary flight restrictions but failed to shut down the airspace system. During the following year, the agency unveiled a new plan for further automating its air traffic control facilities, but progress proved disappointing. In 1994, the FAA shifted to a more step-by-step approach that has provided controllers with advanced equipment.
The Air Commerce Act of May 20, 1926, is the cornerstone of the federal government's regulation of civil aviation. This landmark legislation was passed at the urging of the aviation industry, whose leaders believed the airplane could not reach its full commercial potential without federal action to improve and maintain safety standards. The Act charged the Secretary of Commerce with fostering air commerce, issuing and enforcing air traffic rules, licensing pilots, certifying aircraft, establishing airways, and operating and maintaining aids to air navigation. The newly created Aeronautics Branch, operating under the Department of Commerce assumed primary responsibility for aviation oversight.
The approaching era of jet travel, and a series of midair collisions (most notable was the 1956 Grand Canyon mid-air collision), prompted passage of the Federal Aviation Act of 1958. This legislation gave the CAA's functions to a new independent body, the Federal Aviation Agency. The act transferred air safety regulation from the CAB to the new FAA, and also gave the FAA sole responsibility for a common civil-military system of air navigation and air traffic control. The FAA's first administrator, Elwood R. Quesada, was a former Air Force general and adviser to President Eisenhower.
On October 31, 2013, after outcry from media outlets, including heavy criticism from Nick Bilton of The New York Times, the FAA announced it will allow airlines to expand the passengers use of portable electronic devices during all phases of flight, but mobile phone calls will still be prohibited. Implementation will vary among airlines. The FAA expects many carriers to show that their planes allow passengers to safely use their devices in airplane mode, gate-to-gate, by the end of 2013. Devices must be held or put in the seat-back pocket during the actual takeoff and landing. Mobile phones must be in airplane mode or with mobile service disabled, with no signal bars displayed, and cannot be used for voice communications due to Federal Communications Commission regulations that prohibit any airborne calls using mobile phones. If an air carrier provides Wi-Fi service during flight, passengers may use it. Short-range Bluetooth accessories, like wireless keyboards, can also be used.
In 1967, a new U.S. Department of Transportation (DOT) combined major federal responsibilities for air and surface transport. The Federal Aviation Agency's name changed to the Federal Aviation Administration as it became one of several agencies (e.g., Federal Highway Administration, Federal Railroad Administration, the Coast Guard, and the Saint Lawrence Seaway Commission) within DOT (albeit the largest). The FAA administrator would no longer report directly to the president but would instead report to the Secretary of Transportation. New programs and budget requests would have to be approved by DOT, which would then include these requests in the overall budget and submit it to the president.
The Aeronautics Branch was renamed the Bureau of Air Commerce in 1934 to reflect its enhanced status within the Department. As commercial flying increased, the Bureau encouraged a group of airlines to establish the first three centers for providing air traffic control (ATC) along the airways. In 1936, the Bureau itself took over the centers and began to expand the ATC system. The pioneer air traffic controllers used maps, blackboards, and mental calculations to ensure the safe separation of aircraft traveling along designated routes between cities.
In 2014, the FAA changed a long-standing approach to air traffic control candidates that eliminated preferences based on training and experience at flight schools in favor of a personality test open to anyone irrespective of experience. The move was made to increase flight traffic controller racial diversity. Before the change, candidates who had completed coursework at participating colleges and universities could be "fast-tracked" for consideration. The agency eliminated that program and instead switched to an open system to the general public, with no need for any experience or even a college degree. Instead, applicants could take "a biographical questionnaire" that many applicants found baffling.
The FAA has been cited as an example of regulatory capture, "in which the airline industry openly dictates to its regulators its governing rules, arranging for not only beneficial regulation, but placing key people to head these regulators." Retired NASA Office of Inspector General Senior Special Agent Joseph Gutheinz, who used to be a Special Agent with the Office of Inspector General for the Department of Transportation and with FAA Security, is one of the most outspoken critics of FAA. Rather than commend the agency for proposing a $10.2 million fine against Southwest Airlines for its failure to conduct mandatory inspections in 2008, he was quoted as saying the following in an Associated Press story: "Penalties against airlines that violate FAA directives should be stiffer. At $25,000 per violation, Gutheinz said, airlines can justify rolling the dice and taking the chance on getting caught. He also said the FAA is often too quick to bend to pressure from airlines and pilots." Other experts have been critical of the constraints and expectations under which the FAA is expected to operate. The dual role of encouraging aerospace travel and regulating aerospace travel are contradictory. For example, to levy a heavy penalty upon an airline for violating an FAA regulation which would impact their ability to continue operating would not be considered encouraging aerospace travel.
The boroughs of Liverpool, Knowsley, St Helens and Sefton were included in Merseyside. In Greater Manchester the successor boroughs were Bury, Bolton, Manchester, Oldham (part), Rochdale, Salford, Tameside (part), Trafford (part) and Wigan. Warrington and Widnes, south of the new Merseyside/Greater Manchester border were added to the new non-metropolitan county of Cheshire. The urban districts of Barnoldswick and Earby, Bowland Rural District and the parishes of Bracewell and Brogden and Salterforth from Skipton Rural District in the West Riding of Yorkshire became part of the new Lancashire. One parish, Simonswood, was transferred from the borough of Knowsley in Merseyside to the district of West Lancashire in 1994. In 1998 Blackpool and Blackburn with Darwen became independent unitary authorities.
The Duchy of Lancaster is one of two royal duchies in England. It has landholdings throughout the region and elsewhere, operating as a property company, but also exercising the right of the Crown in the County Palatine of Lancaster. While the administrative boundaries changed in the 1970s, the county palatine boundaries remain the same as the historic boundaries. As a result, the High Sheriffs for Lancashire, Greater Manchester and Merseyside are appointed "within the Duchy and County Palatine of Lancaster".
Lancashire has a mostly comprehensive system with four state grammar schools. Not including sixth form colleges, there are 77 state schools (not including Burnley's new schools) and 24 independent schools. The Clitheroe area has secondary modern schools. Sixth form provision is limited at most schools in most districts, with only Fylde and Lancaster districts having mostly sixth forms at schools. The rest depend on FE colleges and sixth form colleges, where they exist. South Ribble has the largest school population and Fylde the smallest (only three schools). Burnley's schools have had a new broom and have essentially been knocked down and started again in 2006. There are many Church of England and Catholic faith schools in Lancashire.
Lancashire produced well known teams in super league such as St Helens, Wigan, and Warrington. The county was once the focal point for many of the sport's professional competitions including the Lancashire League competition which ran from 1895 to 1970, and the Lancashire County Cup which was abandoned in 1993. Rugby League has also seen a representative fixture between Lancashire and Yorkshire contested 89 times since its inception in 1895. Currently there are several rugby league teams that are based within the ceremonial county which include Blackpool Panthers, East Lancashire Lions, Blackpool Sea Eagles, Bamber Bridge, Leyland Warriors, Chorley Panthers, Blackpool Stanley, Blackpool Scorpions and Adlington Rangers.
Lancashire had a lively culture of choral and classical music, with very large numbers of local church choirs from the 17th century, leading to the foundation of local choral societies from the mid-18th century, often particularly focused on performances of the music of Handel and his contemporaries. It also played a major part in the development of brass bands which emerged in the county, particularly in the textile and coalfield areas, in the 19th century. The first open competition for brass bands was held at Manchester in 1853, and continued annually until the 1980s. The vibrant brass band culture of the area made an important contribution to the foundation and staffing of the Hallé Orchestra from 1857, the oldest extant professional orchestra in the United Kingdom. The same local musical tradition produced eminent figures such as Sir William Walton (1902–88), son of an Oldham choirmaster and music teacher, Sir Thomas Beecham (1879–1961), born in St. Helens, who began his career by conducting local orchestras and Alan Rawsthorne (1905–71) born in Haslingden. The conductor David Atherton, co-founder of the London Sinfonietta, was born in Blackpool in 1944. Lancashire also produced more populist figures, such as early musical theatre composer Leslie Stuart (1863–1928), born in Southport, who began his musical career as organist of Salford Cathedral.
Lancashire emerged as a major commercial and industrial region during the Industrial Revolution. Manchester and Liverpool grew into its largest cities, dominating global trade and the birth of modern capitalism. The county contained several mill towns and the collieries of the Lancashire Coalfield. By the 1830s, approximately 85% of all cotton manufactured worldwide was processed in Lancashire. Accrington, Blackburn, Bolton, Burnley, Bury, Chorley, Colne, Darwen, Nelson, Oldham, Preston, Rochdale and Wigan were major cotton mill towns during this time. Blackpool was a centre for tourism for the inhabitants of Lancashire's mill towns, particularly during wakes week.
The county was subject to significant boundary reform in 1974 that removed Liverpool and Manchester and most of their surrounding conurbations to form the metropolitan counties of Merseyside and Greater Manchester. The detached northern part of Lancashire in the Lake District, including the Furness Peninsula and Cartmel, was merged with Cumberland and Westmorland to form Cumbria. Lancashire lost 709 square miles of land to other counties, about two fifths of its original area, although it did gain some land from the West Riding of Yorkshire. Today the county borders Cumbria to the north, Greater Manchester and Merseyside to the south and North and West Yorkshire to the east; with a coastline on the Irish Sea to the west. The county palatine boundaries remain the same[clarification needed] with the Duke of Lancaster exercising sovereignty rights, including the appointment of lords lieutenant in Greater Manchester and Merseyside.
Lancashire is smaller than its historical extent following a major reform of local government. In 1889, the administrative county of Lancashire was created, covering the historical county except for the county boroughs such as Blackburn, Burnley, Barrow-in-Furness, Preston, Wigan, Liverpool and Manchester. The area served by the Lord-Lieutenant (termed now a ceremonial county) covered the entirety of the administrative county and the county boroughs, and was expanded whenever boroughs annexed areas in neighbouring counties such as Wythenshawe in Manchester south of the River Mersey and historically in Cheshire, and southern Warrington. It did not cover the western part of Todmorden, where the ancient border between Lancashire and Yorkshire passes through the middle of the town.
During the 20th century, the county became increasingly urbanised, particularly the southern part. To the existing county boroughs of Barrow-in-Furness, Blackburn, Bolton, Bootle, Burnley, Bury, Liverpool, Manchester, Oldham, Preston, Rochdale, Salford, St Helens and Wigan were added Blackpool (1904), Southport (1905), and Warrington (1900). The county boroughs also had many boundary extensions. The borders around the Manchester area were particularly complicated, with narrow protrusions of the administrative county between the county boroughs – Lees urban district formed a detached part of the administrative county, between Oldham county borough and the West Riding of Yorkshire.
To the east of the county are upland areas leading to the Pennines. North of the Ribble is Beacon Fell Country Park and the Forest of Bowland, another AONB. Much of the lowland in this area is devoted to dairy farming and cheesemaking, whereas the higher ground is more suitable for sheep, and the highest ground is uncultivated moorland. The valleys of the River Ribble and its tributary the Calder form a large gap to the west of the Pennines, overlooked by Pendle Hill. Most of the larger Lancashire towns are in these valleys South of the Ribble are the West Pennine Moors and the Forest of Rossendale where former cotton mill towns are in deep valleys. The Lancashire Coalfield, largely in modern-day Greater Manchester, extended into Merseyside and to Ormskirk, Chorley, Burnley and Colne in Lancashire.
The Duchy administers bona vacantia within the County Palatine, receiving the property of persons who die intestate and where the legal ownership cannot be ascertained. There is no separate Duke of Lancaster, the title merged into the Crown many centuries ago – but the Duchy is administered by the Queen in Right of the Duchy of Lancaster. A separate court system for the county palatine was abolished by Courts Act 1971. A particular form of The Loyal Toast, 'The Queen, Duke of Lancaster' is in regular use in the county palatine. Lancaster serves as the county town of the county palatine.
The Lancashire economy relies strongly on the M6 motorway which runs from north to south, past Lancaster and Preston. The M55 connects Preston to Blackpool and is 11.5 miles (18.3 km) long. The M65 motorway from Colne, connects Burnley, Accrington, Blackburn to Preston. The M61 from Preston via Chorley and the M66 starting 500 metres (0.3 mi) inside the county boundary near Edenfield, provide links between Lancashire and Manchester] and the trans-Pennine M62. The M58 crosses the southernmost part of the county from the M6 near Wigan to Liverpool via Skelmersdale.
The major settlements in the ceremonial county are concentrated on the Fylde coast (the Blackpool Urban Area), and a belt of towns running west-east along the M65: Preston, Blackburn, Accrington, Burnley, Nelson and Colne. South of Preston are the towns of Leyland and Chorley; the three formed part of the Central Lancashire New Town designated in 1970. The north of the county is predominantly rural and sparsely populated, except for the towns of Lancaster and Morecambe which form a large conurbation of almost 100,000 people. Lancashire is home to a significant Asian population, numbering over 70,000 and 6% of the county's population, and concentrated largely in the former cotton mill towns in the south east.
Liverpool produced a number of nationally and internationally successful popular singers in the 1950s, including traditional pop stars Frankie Vaughan and Lita Roza, and one of the most successful British rock and roll stars in Billy Fury. Many Lancashire towns had vibrant skiffle scenes in the late 1950s, out of which by the early 1960s a flourishing culture of beat groups began to emerge, particularly around Liverpool and Manchester. It has been estimated that there were around 350 bands active in and around Liverpool in this era, often playing ballrooms, concert halls and clubs, among them the Beatles. After their national success from 1962, a number of Liverpool performers were able to follow them into the charts, including Gerry & the Pacemakers, the Searchers and Cilla Black. The first act to break through in the UK who were not from Liverpool, or managed by Brian Epstein, were Freddie and the Dreamers, who were based in Manchester, as were Herman's Hermits and the Hollies. Led by the Beatles, beat groups from the region spearheaded the British Invasion of the US, which made a major contribution to the development of rock music. After the decline of beat groups in the late 1960s the centre of rock culture shifted to London and there were relatively few local bands who achieved national prominence until the growth of a disco funk scene and the punk rock revolution in the mid and late 1970s.
Lancashire has a long and highly productive tradition of music making. In the early modern era the county shared in the national tradition of balladry, including perhaps the finest border ballad, "The Ballad of Chevy Chase", thought to have been composed by the Lancashire-born minstrel Richard Sheale. The county was also a common location for folk songs, including "The Lancashire Miller", "Warrington Ale" and "The soldier's farewell to Manchester", while Liverpool, as a major seaport, was the subject of many sea shanties, including "The Leaving of Liverpool" and "Maggie May", beside several local Wassailing songs. In the Industrial Revolution changing social and economic patterns helped create new traditions and styles of folk song, often linked to migration and patterns of work. These included processional dances, often associated with rushbearing or the Wakes Week festivities, and types of step dance, most famously clog dancing.
The county was established in 1182, later than many other counties. During Roman times the area was part of the Brigantes tribal area in the military zone of Roman Britain. The towns of Manchester, Lancaster, Ribchester, Burrow, Elslack and Castleshaw grew around Roman forts. In the centuries after the Roman withdrawal in 410AD the northern parts of the county probably formed part of the Brythonic kingdom of Rheged, a successor entity to the Brigantes tribe. During the mid-8th century, the area was incorporated into the Anglo-Saxon Kingdom of Northumbria, which became a part of England in the 10th century.
By the census of 1971, the population of Lancashire and its county boroughs had reached 5,129,416, making it the most populous geographic county in the UK. The administrative county was also the most populous of its type outside London, with a population of 2,280,359 in 1961. On 1 April 1974, under the Local Government Act 1972, the administrative county was abolished, as were the county boroughs. The urbanised southern part largely became part of two metropolitan counties, Merseyside and Greater Manchester. The new county of Cumbria incorporates the Furness exclave.
A local pioneer of folk song collection in the first half of the 19th century was Shakespearean scholar James Orchard Halliwell, but it was not until the second folk revival in the 20th century that the full range of song from the county, including industrial folk song, began to gain attention. The county produced one of the major figures of the revival in Ewan MacColl, but also a local champion in Harry Boardman, who from 1965 onwards probably did more than anyone to popularise and record the folk song of the county. Perhaps the most influential folk artists to emerge from the region in the late 20th century were Liverpool folk group The Spinners, and from Manchester folk troubadour Roy Harper and musician, comedian and broadcaster Mike Harding. The region is home to numerous folk clubs, many of them catering to Irish and Scottish folk music. Regular folk festivals include the Fylde Folk Festival at Fleetwood.
The Red Rose of Lancaster is the county flower found on the county's heraldic badge and flag. The rose was a symbol of the House of Lancaster, immortalised in the verse "In the battle for England's head/York was white, Lancaster red" (referring to the 15th-century Wars of the Roses). The traditional Lancashire flag, a red rose on a white field, was not officially registered. When an attempt was made to register it with the Flag Institute it was found that it was officially registered by Montrose in Scotland, several hundred years earlier with the Lyon Office. Lancashire's official flag is registered as a red rose on a gold field.
More recent Lancashire-born composers include Hugh Wood (1932- Parbold), Sir Peter Maxwell Davies (1934-, Salford), Sir Harrison Birtwistle (1934-, Accrington), Gordon Crosse (1937-, Bury),John McCabe (1939-2015, Huyton), Roger Smalley (1943-2015, Swinton), Nigel Osborne (1948-, Manchester), Steve Martland (1954-2013, Liverpool), Simon Holt (1958-, Bolton) and Philip Cashian (1963-, Manchester). The Royal Manchester College of Music was founded in 1893 to provide a northern counterpart to the London musical colleges. It merged with the Northern College of Music (formed in 1920) to form the Royal Northern College of Music in 1972.
The Early Triassic was between 250 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing but arid. The Earth had just witnessed a massive die-off in which 95% of all life went extinct. The most common life on earth were Lystrosaurus, Labyrinthodont, and Euparkeria along with many other creatures that managed to survive the Great Dying. Temnospondyli evolved during this time and would be the dominant predator for much of the Triassic.
The climatic changes of the late Jurassic and Cretaceous provided for further adaptive radiation. The Jurassic was the height of archosaur diversity, and the first birds and eutherian mammals also appeared. Angiosperms radiated sometime in the early Cretaceous, first in the tropics, but the even temperature gradient allowed them to spread toward the poles throughout the period. By the end of the Cretaceous, angiosperms dominated tree floras in many areas, although some evidence suggests that biomass was still dominated by cycad and ferns until after the Cretaceous–Paleogene extinction.
The lower (Triassic) boundary is set by the Permian–Triassic extinction event, during which approximately 90% to 96% of marine species and 70% of terrestrial vertebrates became extinct. It is also known as the "Great Dying" because it is considered the largest mass extinction in the Earth's history. The upper (Cretaceous) boundary is set at the Cretaceous–Tertiary (KT) extinction event (now more accurately called the Cretaceous–Paleogene (or K–Pg) extinction event), which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are also believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs.
The Late Cretaceous spans from 100 million to 65 million years ago. The Late Cretaceous featured a cooling trend that would continue on in the Cenozoic period. Eventually, tropics were restricted to the equator and areas beyond the tropic lines featured extreme seasonal changes in weather. Dinosaurs still thrived as new species such as Tyrannosaurus, Ankylosaurus, Triceratops and Hadrosaurs dominated the food web. In the oceans, Mosasaurs ruled the seas to fill the role of the Ichthyosaurs, and huge plesiosaurs, such as Elasmosaurus, evolved. Also, the first flowering plants evolved. At the end of the Cretaceous, the Deccan traps and other volcanic eruptions were poisoning the atmosphere. As this was continuing, it is thought that a large meteor smashed into earth, creating the Chicxulub Crater in an event known as the K-T Extinction, the fifth and most recent mass extinction event, in which 75% of life on earth went extinct, including all non-avian dinosaurs. Everything over 10 kilograms went extinct. The age of the dinosaurs was over.
The climate of the Cretaceous is less certain and more widely disputed. Higher levels of carbon dioxide in the atmosphere are thought to have caused the world temperature gradient from north to south to become almost flat: temperatures were about the same across the planet. Average temperatures were also higher than today by about 10°C. In fact, by the middle Cretaceous, equatorial ocean waters (perhaps as warm as 20 °C in the deep ocean) may have been too warm for sea life,[dubious – discuss][citation needed] and land areas near the equator may have been deserts despite their proximity to water. The circulation of oxygen to the deep ocean may also have been disrupted.[dubious – discuss] For this reason, large volumes of organic matter that was unable to decompose accumulated, eventually being deposited as "black shale".
The Late Triassic spans from 237 million to 200 million years ago. Following the bloom of the Middle Triassic, the Late Triassic featured frequent heat spells, as well as moderate precipitation (10-20 inches per year). The recent warming led to a boom of reptilian evolution on land as the first true dinosaurs evolve, as well as pterosaurs. All this climatic change, however, resulted in a large die-out known as the Triassic-Jurassic extinction event, in which all archosaurs (excluding ancient crocodiles), most synapsids, and almost all large amphibians went extinct, as well as 34% of marine life in the fourth mass extinction event of the world. The cause is debatable.
The Early Cretaceous spans from 145 million to 100 million years ago. The Early Cretaceous saw the expansion of seaways, and as a result, the decline and extinction of sauropods (except in South America). Many coastal shallows were created, and that caused Ichthyosaurs to die out. Mosasaurs evolved to replace them as head of the seas. Some island-hopping dinosaurs, like Eustreptospondylus, evolved to cope with the coastal shallows and small islands of ancient Europe. Other dinosaurs rose up to fill the empty space that the Jurassic-Cretaceous extinction left behind, such as Carcharodontosaurus and Spinosaurus. Of the most successful would be the Iguanodon which spread to every continent. Seasons came back into effect and the poles got seasonally colder, but dinosaurs still inhabited this area like the Leaellynasaura which inhabited the polar forests year-round, and many dinosaurs migrated there during summer like Muttaburrasaurus. Since it was too cold for crocodiles, it was the last stronghold for large amphibians, like Koolasuchus. Pterosaurs got larger as species like Tapejara and Ornithocheirus evolved.
Sea levels began to rise during the Jurassic, which was probably caused by an increase in seafloor spreading. The formation of new crust beneath the surface displaced ocean waters by as much as 200 m (656 ft) more than today, which flooded coastal areas. Furthermore, Pangaea began to rift into smaller divisions, bringing more land area in contact with the ocean by forming the Tethys Sea. Temperatures continued to increase and began to stabilize. Humidity also increased with the proximity of water, and deserts retreated.
The Early Jurassic spans from 200 million years to 175 million years ago. The climate was much more humid than the Triassic, and as a result, the world was very tropical. In the oceans, Plesiosaurs, Ichthyosaurs and Ammonites fill waters as the dominant races of the seas. On land, dinosaurs and other reptiles stake their claim as the dominant race of the land, with species such as Dilophosaurus at the top. The first true crocodiles evolved, pushing out the large amphibians to near extinction. All-in-all, reptiles rise to rule the world. Meanwhile, the first true mammals evolve, but remained relatively small sized.
Compared to the vigorous convergent plate mountain-building of the late Paleozoic, Mesozoic tectonic deformation was comparatively mild. The sole major Mesozoic orogeny occurred in what is now the Arctic, creating the Innuitian orogeny, the Brooks Range, the Verkhoyansk and Cherskiy Ranges in Siberia, and the Khingan Mountains in Manchuria. This orogeny was related to the opening of the Arctic Ocean and subduction of the North China and Siberian cratons under the Pacific Ocean. Nevertheless, the era featured the dramatic rifting of the supercontinent Pangaea. Pangaea gradually split into a northern continent, Laurasia, and a southern continent, Gondwana. This created the passive continental margin that characterizes most of the Atlantic coastline (such as along the U.S. East Coast) today.
Recent research indicates that the specialized animals that formed complex ecosystems, with high biodiversity, complex food webs and a variety of niches, took much longer to reestablish, recovery did not begin until the start of the mid-Triassic, 4M to 6M years after the extinction and was not complete until 30M years after the Permian–Triassic extinction event. Animal life was then dominated by various archosaurian reptiles: dinosaurs, pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs.
The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction which is known for having killed off non-avian dinosaurs, as well as other plant and animal species. The Mesozoic was a time of significant tectonic, climate and evolutionary activity. The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today. Non-avian dinosaurs appeared in the Late Triassic and became the dominant terrestrial vertebrates early in the Jurassic, occupying this position for about 135 million years until their demise at the end of the Cretaceous. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs. The first mammals also appeared during the Mesozoic, but would remain small—less than 15 kg (33 lb)—until the Cenozoic.
The Middle Triassic spans from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, and the beginning of the Tethys Sea. The ecosystem had recovered from the devastation that was the Great Dying. Phytoplankton, coral, and crustaceans all had recovered, and the reptiles began to get bigger and bigger. New aquatic reptiles evolved such as Ichthyosaurs and Nothosaurs. Meanwhile, on land, Pine forests flourished, bringing along mosquitoes and fruit flies. The first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world.
The Late Jurassic spans from 163 million to 145 million years ago. The Late Jurassic featured a massive extinction of sauropods and Ichthyosaurs due to the separation of Pangaea into Laurasia and Gondwana in an extinction known as the Jurassic-Cretaceous extinction. Sea levels rose, destroying fern prairies and creating shallows in its wake. Ichthyosaurs went extinct whereas sauropods, as a whole, did not die out in the Jurassic; in fact, some species, like the Titanosaurus, lived up to the K-T extinction. The increase in sea-levels opened up the Atlantic sea way which would continue to get larger over time. The divided world would give opportunity for the diversification of new dinosaurs.
The Triassic was generally dry, a trend that began in the late Carboniferous, and highly seasonal, especially in the interior of Pangaea. Low sea levels may have also exacerbated temperature extremes. With its high specific heat capacity, water acts as a temperature-stabilizing heat reservoir, and land areas near large bodies of water—especially the oceans—experience less variation in temperature. Because much of the land that constituted Pangaea was distant from the oceans, temperatures fluctuated greatly, and the interior of Pangaea probably included expansive areas of desert. Abundant red beds and evaporites such as halite support these conclusions, but evidence exists that the generally dry climate of the Triassic was punctuated by episodes of increased rainfall. Most important humid episodes were the Carnian Pluvial Event and one in the Rhaetian, few million years before the Triassic–Jurassic extinction event.
The dominant land plant species of the time were gymnosperms, which are vascular, cone-bearing, non-flowering plants such as conifers that produce seeds without a coating. This is opposed to the earth's current flora, in which the dominant land plants in terms of number of species are angiosperms. One particular plant genus, Ginkgo, is thought to have evolved at this time and is represented today by a single species, Ginkgo biloba. As well, the extant genus Sequoia is believed to have evolved in the Mesozoic.
It was only in the 1980s that digital telephony transmission networks became possible, such as with ISDN networks, assuring a minimum bit rate (usually 128 kilobits/s) for compressed video and audio transmission. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research. The first dedicated systems started to appear in the market as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984.
The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls. This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference.
High speed Internet connectivity has become more widely available at a reasonable cost and the cost of video capture and display technology has decreased. Consequently, personal videoconferencing systems based on a webcam, personal computer system, software compression and broadband Internet connectivity have become affordable to the general public. Also, the hardware used for this technology has continued to improve in quality, and prices have dropped dramatically. The availability of freeware (often as part of chat programs) has made software based videoconferencing accessible to many.
Videophone calls (also: videocalls, video chat as well as Skype and Skyping in verb form), differ from videoconferencing in that they expect to serve individuals, not groups. However that distinction has become increasingly blurred with technology improvements such as increased bandwidth and sophisticated software clients that can allow for multiple parties on a call. In general everyday usage the term videoconferencing is now frequently used instead of videocall for point-to-point calls between two units. Both videophone calls and videoconferencing are also now commonly referred to as a video link.
Technological developments by videoconferencing developers in the 2010s have extended the capabilities of video conferencing systems beyond the boardroom for use with hand-held mobile devices that combine the use of video, audio and on-screen drawing capabilities broadcasting in real-time over secure networks, independent of location. Mobile collaboration systems now allow multiple people in previously unreachable locations, such as workers on an off-shore oil rig, the ability to view and discuss issues with colleagues thousands of miles away. Traditional videoconferencing system manufacturers have begun providing mobile applications as well, such as those that allow for live and still image streaming.
Videoconferencing provides students with the opportunity to learn by participating in two-way communication forums. Furthermore, teachers and lecturers worldwide can be brought to remote or otherwise isolated educational facilities. Students from diverse communities and backgrounds can come together to learn about one another, although language barriers will continue to persist. Such students are able to explore, communicate, analyze and share information and ideas with one another. Through videoconferencing, students can visit other parts of the world to speak with their peers, and visit museums and educational facilities. Such virtual field trips can provide enriched learning opportunities to students, especially those in geographically isolated locations, and to the economically disadvantaged. Small schools can use these technologies to pool resources and provide courses, such as in foreign languages, which could not otherwise be offered.
One of the first demonstrations of the ability for telecommunications to help sign language users communicate with each other occurred when AT&T's videophone (trademarked as the "Picturephone") was introduced to the public at the 1964 New York World's Fair –two deaf users were able to communicate freely with each other between the fair and another city. Various universities and other organizations, including British Telecom's Martlesham facility, have also conducted extensive research on signing via videotelephony. The use of sign language via videotelephony was hampered for many years due to the difficulty of its use over slow analogue copper phone lines, coupled with the high cost of better quality ISDN (data) phone lines. Those factors largely disappeared with the introduction of more efficient video codecs and the advent of lower cost high-speed ISDN data and IP (Internet) services in the 1990s.
In the increasingly globalized film industry, videoconferencing has become useful as a method by which creative talent in many different locations can collaborate closely on the complex details of film production. For example, for the 2013 award-winning animated film Frozen, Burbank-based Walt Disney Animation Studios hired the New York City-based husband-and-wife songwriting team of Robert Lopez and Kristen Anderson-Lopez to write the songs, which required two-hour-long transcontinental videoconferences nearly every weekday for about 14 months.
A videoconference system is generally higher cost than a videophone and deploys greater capabilities. A videoconference (also known as a videoteleconference) allows two or more locations to communicate via live, simultaneous two-way video and audio transmissions. This is often accomplished by the use of a multipoint control unit (a centralized distribution and call management system) or by a similar non-centralized multipoint capability embedded in each videoconferencing unit. Again, technology improvements have circumvented traditional definitions by allowing multiple party videoconferencing via web-based applications.
This technique was very expensive, though, and could not be used for applications such as telemedicine, distance education, and business meetings. Attempts at using normal telephony networks to transmit slow-scan video, such as the first systems developed by AT&T Corporation, first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient video compression techniques. The greater 1 MHz bandwidth and 6 Mbit/s bit rate of the Picturephone in the 1970s also did not achieve commercial success, mostly due to its high cost, but also due to a lack of network effect —with only a few hundred Picturephones in the world, users had extremely few contacts they could actually call to, and interoperability with other videophone systems would not exist for decades.
While videoconferencing technology was initially used primarily within internal corporate communication networks, one of the first community service usages of the technology started in 1992 through a unique partnership with PictureTel and IBM Corporations which at the time were promoting a jointly developed desktop based videoconferencing product known as the PCS/1. Over the next 15 years, Project DIANE (Diversified Information and Assistance Network) grew to utilize a variety of videoconferencing platforms to create a multi-state cooperative public service and distance education network consisting of several hundred schools, neighborhood centers, libraries, science museums, zoos and parks, public assistance centers, and other community oriented organizations.
Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a similar way to the audio conference call). All parties call the MCU, or the MCU can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCUs which are pure software, and others which are a combination of hardware and software. An MCU is characterised according to the number of simultaneous calls it can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-alone hardware devices, or they can be embedded into dedicated videoconferencing units.
Videoconferencing can enable individuals in distant locations to participate in meetings on short notice, with time and money savings. Technology such as VoIP can be used in conjunction with desktop videoconferencing to enable low-cost face-to-face business meetings without leaving the desk, especially for businesses with widespread offices. The technology is also used for telecommuting, in which employees work from home. One research report based on a sampling of 1,800 corporate employees showed that, as of June 2010, 54% of the respondents with access to video conferencing used it “all of the time” or “frequently”.
Finally, in the 1990s, Internet Protocol-based videoconferencing became possible, and more efficient video compression technologies were developed, permitting desktop, or personal computer (PC)-based videoconferencing. In 1992 CU-SeeMe was developed at Cornell by Tim Dorcey et al. In 1995 the first public videoconference between North America and Africa took place, linking a technofair in San Francisco with a techno-rave and cyberdeli in Cape Town. At the Winter Olympics opening ceremony in Nagano, Japan, Seiji Ozawa conducted the Ode to Joy from Beethoven's Ninth Symphony simultaneously across five continents in near-real time.
The core technology used in a videoconferencing system is digital compression of audio and video streams in real time. The hardware or software that performs compression is called a codec (coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1s and 0s is subdivided into labeled packets, which are then transmitted through a digital network of some kind (usually ISDN or IP). The use of audio modems in the transmission line allow for the use of POTS, or the Plain Old Telephone System, in some low-speed applications, such as videotelephony, because they convert the digital pulses to/from analog waves in the audio spectrum range.
Typical use of the various technologies described above include calling or conferencing on a one-on-one, one-to-many or many-to-many basis for personal, business, educational, deaf Video Relay Service and tele-medical, diagnostic and rehabilitative use or services. New services utilizing videocalling and videoconferencing, such as teachers and psychologists conducting online sessions, personal videocalls to inmates incarcerated in penitentiaries, and videoconferencing to resolve airline engineering issues at maintenance facilities, are being created or evolving on an ongoing basis.
Videoconferencing is a highly useful technology for real-time telemedicine and telenursing applications, such as diagnosis, consulting, transmission of medical images, etc... With videoconferencing, patients may contact nurses and physicians in emergency or routine situations; physicians and other paramedical professionals can discuss cases across large distances. Rural areas can use this technology for diagnostic purposes, thus saving lives and making more efficient use of health care money. For example, a rural medical center in Ohio, United States, used videoconferencing to successfully cut the number of transfers of sick infants to a hospital 70 miles (110 km) away. This had previously cost nearly $10,000 per transfer.
VRS services have become well developed nationally in Sweden since 1997 and also in the United States since the first decade of the 2000s. With the exception of Sweden, VRS has been provided in Europe for only a few years since the mid-2000s, and as of 2010 has not been made available in many European Union countries, with most European countries still lacking the legislation or the financing for large-scale VRS services, and to provide the necessary telecommunication equipment to deaf users. Germany and the Nordic countries are among the other leaders in Europe, while the United States is another world leader in the provisioning of VRS services.
In May 2005, the first high definition video conferencing systems, produced by LifeSize Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide video at 30 frames per second with a 1280 by 720 display resolution. Polycom introduced its first high definition video conferencing system to the market in 2006. As of the 2010s, high definition resolution for videoconferencing became a popular feature, with most major suppliers in the videoconferencing market offering it.
Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or otherwise. These use a standards-based H.323 technique known as "decentralized multipoint", where each station in a multipoint call exchanges video and audio directly with the other stations with no central "manager" or other bottleneck. The advantages of this technique are that the video and audio will generally be of higher quality because they don't have to be relayed through a central point. Also, users can make ad-hoc multipoint calls without any concern for the availability or control of an MCU. This added convenience and quality comes at the expense of some increased network bandwidth, because every station must transmit to every other station directly.
The U.S. Social Security Administration (SSA), which oversees the world's largest administrative judicial system under its Office of Disability Adjudication and Review (ODAR), has made extensive use of videoconferencing to conduct hearings at remote locations. In Fiscal Year (FY) 2009, the U.S. Social Security Administration (SSA) conducted 86,320 videoconferenced hearings, a 55% increase over FY 2008. In August 2010, the SSA opened its fifth and largest videoconferencing-only National Hearing Center (NHC), in St. Louis, Missouri. This continues the SSA's effort to use video hearings as a means to clear its substantial hearing backlog. Since 2007, the SSA has also established NHCs in Albuquerque, New Mexico, Baltimore, Maryland, Falls Church, Virginia, and Chicago, Illinois.
To unambiguously specify the date, dual dating or Old Style (O.S.) and New Style (N.S.) are sometimes used with dates. Dual dating uses two consecutive years because of differences in the starting date of the year, or includes both the Julian and Gregorian dates. Old Style and New Style (N.S.) indicate either whether the start of the Julian year has been adjusted to start on 1 January (N.S.) even though documents written at the time use a different start of year (O.S.), or whether a date conforms to the Julian calendar (O.S.) rather than the Gregorian (N.S.).
The Gregorian calendar was a reform of the Julian calendar instituted in 1582 by Pope Gregory XIII, after whom the calendar was named, by papal bull Inter gravissimas dated 24 February 1582. The motivation for the adjustment was to bring the date for the celebration of Easter to the time of year in which it was celebrated when it was introduced by the early Church. Although a recommendation of the First Council of Nicaea in 325 specified that all Christians should celebrate Easter on the same day, it took almost five centuries before virtually all Christians achieved that objective by adopting the rules of the Church of Alexandria (see Easter for the issues which arose).
Philip II of Spain decreed the change from the Julian to the Gregorian calendar, which affected much of Roman Catholic Europe, as Philip was at the time ruler over Spain and Portugal as well as much of Italy. In these territories, as well as in the Polish–Lithuanian Commonwealth (ruled by Anna Jagiellon) and in the Papal States, the new calendar was implemented on the date specified by the bull, with Julian Thursday, 4 October 1582, being followed by Gregorian Friday, 15 October 1582. The Spanish and Portuguese colonies followed somewhat later de facto because of delay in communication.
During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their numbered year on 1 January while others were still using some other date. Even before 1582, the year sometimes had to be double dated because of the different beginnings of the year in various countries. Woolley, writing in his biography of John Dee (1527–1608/9), notes that immediately after 1582 English letter writers "customarily" used "two dates" on their letters, one OS and one NS.
The calendar was a refinement to the Julian calendar amounting to a 0.002% correction in the length of the year. The motivation for the reform was to bring the date for the celebration of Easter to the time of the year in which it was celebrated when it was introduced by the early Church. Because the celebration of Easter was tied to the spring equinox, the Roman Catholic Church considered the steady drift in the date of Easter caused by the year being slightly too long to be undesirable. The reform was adopted initially by the Catholic countries of Europe. Protestants and Eastern Orthodox countries continued to use the traditional Julian calendar and adopted the Gregorian reform after a time, for the sake of convenience in international trade. The last European country to adopt the reform was Greece, in 1923.
The Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days, but as in the Julian calendar, in a leap year, a leap day is added to February. In the Julian calendar a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years. In the Julian calendar, this leap day was inserted by doubling 24 February, and the Gregorian reform did not change the date of the leap day. In the modern period, it has become customary to number the days from the beginning of the month, and February 29th is often considered as the leap day. Some churches, notably the Roman Catholic Church, delay February festivals after the 23rd by one day in leap years.
Easter was the Sunday after the 15th day of this moon, whose 14th day was allowed to precede the equinox. Where the two systems produced different dates there was generally a compromise so that both churches were able to celebrate on the same day. By the 10th century all churches (except some on the eastern border of the Byzantine Empire) had adopted the Alexandrian Easter, which still placed the vernal equinox on 21 March, although Bede had already noted its drift in 725—it had drifted even further by the 16th century.
Lilius's proposals had two components. Firstly, he proposed a correction to the length of the year. The mean tropical year is 365.24219 days long. As the average length of a Julian year is 365.25 days, the Julian year is almost 11 minutes longer than the mean tropical year. The discrepancy results in a drift of about three days every 400 years. Lilius's proposal resulted in an average year of 365.2425 days (see Accuracy). At the time of Gregory's reform there had already been a drift of 10 days since the Council of Nicaea, resulting in the vernal equinox falling on 10 or 11 March instead of the ecclesiastically fixed date of 21 March, and if unreformed it would drift further. Lilius proposed that the 10-day drift should be corrected by deleting the Julian leap day on each of its ten occurrences over a period of forty years, thereby providing for a gradual return of the equinox to 21 March.
Most Western European countries changed the start of the year to 1 January before they adopted the Gregorian calendar. For example, Scotland changed the start of the Scottish New Year to 1 January in 1600 (this means that 1599 was a short year). England, Ireland and the British colonies changed the start of the year to 1 January in 1752 (so 1751 was a short year with only 282 days) though in England the start of the tax year remained at 25 March (O.S.), 5 April (N.S.) till 1800, when it moved to 6 April. Later in 1752 in September the Gregorian calendar was introduced throughout Britain and the British colonies (see the section Adoption). These two reforms were implemented by the Calendar (New Style) Act 1750.
Extending the Gregorian calendar backwards to dates preceding its official introduction produces a proleptic calendar, which should be used with some caution. For ordinary purposes, the dates of events occurring prior to 15 October 1582 are generally shown as they appeared in the Julian calendar, with the year starting on 1 January, and no conversion to their Gregorian equivalents. For example, the Battle of Agincourt is universally considered to have been fought on 25 October 1415 which is Saint Crispin's Day.
A language-independent alternative used in many countries is to hold up one's two fists with the index knuckle of the left hand against the index knuckle of the right hand. Then, starting with January from the little knuckle of the left hand, count knuckle, space, knuckle, space through the months. A knuckle represents a month of 31 days, and a space represents a short month (a 28- or 29-day February or any 30-day month). The junction between the hands is not counted, so the two index knuckles represent July and August.
The Gregorian reform contained two parts: a reform of the Julian calendar as used prior to Pope Gregory XIII's time and a reform of the lunar cycle used by the Church, with the Julian calendar, to calculate the date of Easter. The reform was a modification of a proposal made by Aloysius Lilius. His proposal included reducing the number of leap years in four centuries from 100 to 97, by making 3 out of 4 centurial years common instead of leap years. Lilius also produced an original and practical scheme for adjusting the epacts of the moon when calculating the annual date of Easter, solving a long-standing obstacle to calendar reform.
Prior to 1917, Turkey used the lunar Islamic calendar with the Hegira era for general purposes and the Julian calendar for fiscal purposes. The start of the fiscal year was eventually fixed at 1 March and the year number was roughly equivalent to the Hegira year (see Rumi calendar). As the solar year is longer than the lunar year this originally entailed the use of "escape years" every so often when the number of the fiscal year would jump. From 1 March 1917 the fiscal year became Gregorian, rather than Julian. On 1 January 1926 the use of the Gregorian calendar was extended to include use for general purposes and the number of the year became the same as in other countries.
Up to February 28 in the calendar you are converting from add one day less or subtract one day more than the calculated value. Remember to give February the appropriate number of days for the calendar you are converting into. When you are subtracting days to move from Julian to Gregorian be careful, when calculating the Gregorian equivalent of February 29 (Julian), to remember that February 29 is discounted. Thus if the calculated value is -4 the Gregorian equivalent of this date is February 24.
In addition to the change in the mean length of the calendar year from 365.25 days (365 days 6 hours) to 365.2425 days (365 days 5 hours 49 minutes 12 seconds), a reduction of 10 minutes 48 seconds per year, the Gregorian calendar reform also dealt with the accumulated difference between these lengths. The canonical Easter tables were devised at the end of the third century, when the vernal equinox fell either on 20 March or 21 March depending on the year's position in the leap year cycle. As the rule was that the full moon preceding Easter was not to precede the equinox the equinox was fixed at 21 March for computational purposes and the earliest date for Easter was fixed at 22 March. The Gregorian calendar reproduced these conditions by removing ten days.
The Council of Trent approved a plan in 1563 for correcting the calendrical errors, requiring that the date of the vernal equinox be restored to that which it held at the time of the First Council of Nicaea in 325 and that an alteration to the calendar be designed to prevent future drift. This would allow for a more consistent and accurate scheduling of the feast of Easter. In 1577, a Compendium was sent to expert mathematicians outside the reform commission for comments. Some of these experts, including Giambattista Benedetti and Giuseppe Moleto, believed Easter should be computed from the true motions of the sun and moon, rather than using a tabular method, but these recommendations were not adopted. The reform adopted was a modification of a proposal made by the Calabrian doctor Aloysius Lilius (or Lilio).
A month after having decreed the reform, the pope with a brief of 3 April 1582 granted to Antonio Lilio, the brother of Luigi Lilio, the exclusive right to publish the calendar for a period of ten years. The Lunario Novo secondo la nuova riforma printed by Vincenzo Accolti, one of the first calendars printed in Rome after the reform, notes at the bottom that it was signed with papal authorization and by Lilio (Con licentia delli Superiori... et permissu Ant(onii) Lilij). The papal brief was later revoked, on 20 September 1582, because Antonio Lilio proved unable to keep up with the demand for copies.
The year used in dates during the Roman Republic and the Roman Empire was the consular year, which began on the day when consuls first entered office—probably 1 May before 222 BC, 15 March from 222 BC and 1 January from 153 BC. The Julian calendar, which began in 45 BC, continued to use 1 January as the first day of the new year. Even though the year used for dates changed, the civil year always displayed its months in the order January to December from the Roman Republican period until the present.
In conjunction with the system of months there is a system of weeks. A physical or electronic calendar provides conversion from a given date to the weekday, and shows multiple dates for a given weekday and month. Calculating the day of the week is not very simple, because of the irregularities in the Gregorian system. When the Gregorian calendar was adopted by each country, the weekly cycle continued uninterrupted. For example, in the case of the few countries that adopted the reformed calendar on the date proposed by Gregory XIII for the calendar's adoption, Friday, 15 October 1582, the preceding date was Thursday, 4 October 1582 (Julian calendar).
Because the spring equinox was tied to the date of Easter, the Roman Catholic Church considered the seasonal drift in the date of Easter undesirable. The Church of Alexandria celebrated Easter on the Sunday after the 14th day of the moon (computed using the Metonic cycle) that falls on or after the vernal equinox, which they placed on 21 March. However, the Church of Rome still regarded 25 March as the equinox (until 342) and used a different cycle to compute the day of the moon. In the Alexandrian system, since the 14th day of the Easter moon could fall at earliest on 21 March its first day could fall no earlier than 8 March and no later than 5 April. This meant that Easter varied between 22 March and 25 April. In Rome, Easter was not allowed to fall later than 21 April, that being the day of the Parilia or birthday of Rome and a pagan festival.The first day of the Easter moon could fall no earlier than 5 March and no later than 2 April.
Ancient tables provided the sun's mean longitude. Christopher Clavius, the architect of the Gregorian calendar, noted that the tables agreed neither on the time when the sun passed through the vernal equinox nor on the length of the mean tropical year. Tycho Brahe also noticed discrepancies. The Gregorian leap year rule (97 leap years in 400 years) was put forward by Petrus Pitatus of Verona in 1560. He noted that it is consistent with the tropical year of the Alfonsine tables and with the mean tropical year of Copernicus (De revolutionibus) and Reinhold (Prutenic tables). The three mean tropical years in Babylonian sexagesimals as the excess over 365 days (the way they would have been extracted from the tables of mean longitude) were 14,33,9,57 (Alphonsine), 14,33,11,12 (Copernicus) and 14,33,9,24 (Reinhold). All values are the same to two places (14:33) and this is also the mean length of the Gregorian year. Thus Pitatus' solution would have commended itself to the astronomers.
"Old Style" (OS) and "New Style" (NS) are sometimes added to dates to identify which system is used in the British Empire and other countries that did not immediately change. Because the Calendar Act of 1750 altered the start of the year, and also aligned the British calendar with the Gregorian calendar, there is some confusion as to what these terms mean. They can indicate that the start of the Julian year has been adjusted to start on 1 January (NS) even though contemporary documents use a different start of year (OS); or to indicate that a date conforms to the Julian calendar (OS), formerly in use in many countries, rather than the Gregorian calendar (NS).
The Gregorian calendar improves the approximation made by the Julian calendar by skipping three Julian leap days in every 400 years, giving an average year of 365.2425 mean solar days long. This approximation has an error of about one day per 3,300 years with respect to the mean tropical year. However, because of the precession of the equinoxes, the error with respect to the vernal equinox (which occurs, on average, 365.24237 days apart near 2000) is 1 day every 7,700 years, assuming a constant time interval between vernal equinoxes, which is not true. By any criterion, the Gregorian calendar is substantially more accurate than the 1 day in 128 years error of the Julian calendar (average year 365.25 days).
Known during development as Xbox Next, Xenon, Xbox 2, Xbox FS or NextBox, the Xbox 360 was conceived in early 2003. In February 2003, planning for the Xenon software platform began, and was headed by Microsoft's Vice President J Allard. That month, Microsoft held an event for 400 developers in Bellevue, Washington to recruit support for the system. Also that month, Peter Moore, former president of Sega of America, joined Microsoft. On August 12, 2003, ATI signed on to produce the graphic processing unit for the new console, a deal which was publicly announced two days later. Before the launch of the Xbox 360, several Alpha development kits were spotted using Apple's Power Mac G5 hardware. This was because the system's PowerPC 970 processor running the same PowerPC architecture that the Xbox 360 would eventually run under IBM's Xenon processor. The cores of the Xenon processor were developed using a slightly modified version of the PlayStation 3's Cell Processor PPE architecture. According to David Shippy and Mickie Phipps, the IBM employees were "hiding" their work from Sony and Toshiba, IBM's partners in developing the Cell Processor. Jeff Minter created the music visualization program Neon which is included with the Xbox 360.
At launch, the Xbox 360 was available in two configurations: the "Xbox 360" package (unofficially known as the 20 GB Pro or Premium), priced at US$399 or GB£279.99, and the "Xbox 360 Core", priced at US$299 and GB£209.99. The original shipment of the Xbox 360 version included a cut-down version of the Media Remote as a promotion. The Elite package was launched later at US$479. The "Xbox 360 Core" was replaced by the "Xbox 360 Arcade" in October 2007 and a 60 GB version of the Xbox 360 Pro was released on August 1, 2008. The Pro package was discontinued and marked down to US$249 on August 28, 2009 to be sold until stock ran out, while the Elite was also marked down in price to US$299.
The Xbox 360 launched with 14 games in North America and 13 in Europe. The console's best-selling game for 2005, Call of Duty 2, sold over a million copies. Five other games sold over a million copies in the console's first year on the market: Ghost Recon Advanced Warfighter, The Elder Scrolls IV: Oblivion, Dead or Alive 4, Saints Row, and Gears of War. Gears of War would become the best-selling game on the console with 3 million copies in 2006, before being surpassed in 2007 by Halo 3 with over 8 million copies.
The Xbox 360 supports videos in Windows Media Video (WMV) format (including high-definition and PlaysForSure videos), as well as H.264 and MPEG-4 media. The December 2007 dashboard update added support for the playback of MPEG-4 ASP format videos. The console can also display pictures and perform slideshows of photo collections with various transition effects, and supports audio playback, with music player controls accessible through the Xbox 360 Guide button. Users may play back their own music while playing games or using the dashboard, and can play music with an interactive visual synthesizer.
When the Xbox 360 was released, Microsoft's online gaming service Xbox Live was shut down for 24 hours and underwent a major upgrade, adding a basic non-subscription service called Xbox Live Silver (later renamed Xbox Live Free) to its already established premium subscription-based service (which was renamed Gold). Xbox Live Free is included with all SKUs of the console. It allows users to create a user profile, join on message boards, and access Microsoft's Xbox Live Arcade and Marketplace and talk to other members. A Live Free account does not generally support multiplayer gaming; however, some games that have rather limited online functions already, (such as Viva Piñata) or games that feature their own subscription service (e.g. EA Sports games) can be played with a Free account. Xbox Live also supports voice the latter a feature possible with the Xbox Live Vision.
The Xbox 360 features an online service, Xbox Live, which was expanded from its previous iteration on the original Xbox and received regular updates during the console's lifetime. Available in free and subscription-based varieties, Xbox Live allows users to: play games online; download games (through Xbox Live Arcade) and game demos; purchase and stream music, television programs, and films through the Xbox Music and Xbox Video portals; and access third-party content services through media streaming applications. In addition to online multimedia features, the Xbox 360 allows users to stream media from local PCs. Several peripherals have been released, including wireless controllers, expanded hard drive storage, and the Kinect motion sensing camera. The release of these additional services and peripherals helped the Xbox brand grow from gaming-only to encompassing all multimedia, turning it into a hub for living-room computing entertainment.
The Xbox 360's advantage over its competitors was due to the release of high profile titles from both first party and third party developers. The 2007 Game Critics Awards honored the platform with 38 nominations and 12 wins – more than any other platform. By March 2008, the Xbox 360 had reached a software attach rate of 7.5 games per console in the US; the rate was 7.0 in Europe, while its competitors were 3.8 (PS3) and 3.5 (Wii), according to Microsoft. At the 2008 Game Developers Conference, Microsoft announced that it expected over 1,000 games available for Xbox 360 by the end of the year. As well as enjoying exclusives such as additions to the Halo franchise and Gears of War, the Xbox 360 has managed to gain a simultaneous release of titles that were initially planned to be PS3 exclusives, including Devil May Cry, Ace Combat, Virtua Fighter, Grand Theft Auto IV, Final Fantasy XIII, Tekken 6, Metal Gear Solid : Rising, and L.A. Noire. In addition, Xbox 360 versions of cross-platform games were generally considered superior to their PS3 counterparts in 2006 and 2007, due in part to the difficulties of programming for the PS3.
To aid customers with defective consoles, Microsoft extended the Xbox 360's manufacturer's warranty to three years for hardware failure problems that generate a "General Hardware Failure" error report. A "General Hardware Failure" is recognized on all models released before the Xbox 360 S by three quadrants of the ring around the power button flashing red. This error is often known as the "Red Ring of Death". In April 2009 the warranty was extended to also cover failures related to the E74 error code. The warranty extension is not granted for any other types of failures that do not generate these specific error codes.
In 2009, IGN named the Xbox 360 the sixth-greatest video game console of all time, out of a field of 25. Although not the best-selling console of the seventh-generation, the Xbox 360 was deemed by TechRadar to be the most influential, by emphasizing digital media distribution and online gaming through Xbox Live, and by popularizing game achievement awards. PC Magazine considered the Xbox 360 the prototype for online gaming as it "proved that online gaming communities could thrive in the console space". Five years after the Xbox 360's original debut, the well-received Kinect motion capture camera was released, which set the record of being the fastest selling consumer electronic device in history, and extended the life of the console. Edge ranked Xbox 360 the second-best console of the 1993–2013 period, stating "It had its own social network, cross-game chat, new indie games every week, and the best version of just about every multiformat game...Killzone is no Halo and nowadays Gran Turismo is no Forza, but it's not about the exclusives—there's nothing to trump Naughty Dog's PS3 output, after all. Rather, it's about the choices Microsoft made back in the original Xbox's lifetime. The PC-like architecture meant those early EA Sports titles ran at 60fps compared to only 30 on PS3, Xbox Live meant every dedicated player had an existing friends list, and Halo meant Microsoft had the killer next-generation exclusive. And when developers demo games on PC now they do it with a 360 pad—another industry benchmark, and a critical one."
The Xbox 360 sold much better than its predecessor, and although not the best-selling console of the seventh-generation, it is regarded as a success since it strengthened Microsoft as a major force in the console market at the expense of well-established rivals. The inexpensive Nintendo Wii did sell the most console units but eventually saw a collapse of third-party software support in its later years, and it has been viewed by some as a fad since the succeeding Wii U had a poor debut in 2012. The PlayStation 3 struggled for a time due to being too expensive and initially lacking quality titles, making it far less dominant than its predecessor, the PlayStation 2, and it took until late in the PlayStation 3's lifespan for its sales and game titles to reach parity with the Xbox 360. TechRadar proclaimed that "Xbox 360 passes the baton as the king of the hill – a position that puts all the more pressure on its successor, Xbox One".

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