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Communion

Communion may refer to:

Religion

 * Eucharist (also called Holy Communion or the Lord's Supper), the Christian rite involving the eating of bread and drinking of wine, reenacting the Last Supper
 * Communion (chant), the Gregorian chant that accompanies this rite
 * First Communion, a ceremony in some Christian traditions during which a person receives the Eucharist for the first time
 * Koinonia (communion or fellowship), the relationship between Christians as individuals and as churches
 * Communion of Saints, a doctrine of Christianity mentioned in the Apostles' Creed
 * Full communion, recognition between churches

Films and literature

 * Communion (2016 film), a documentary
 * Communion (book), a book by Whitley Strieber about his purported abductions by aliens
 * Communion (1989 film), a film based on the book
 * Alice, Sweet Alice or Communion, a 1976 horror film starring Brooke Shields

Music

 * Communion (Roy Campbell album) (1995)
 * Communion (John Patitucci album) (2001)
 * Communion (Septicflesh album) (2008)
 * Communion (The Soundtrack of Our Lives album) (2008)
 * Communion (Years & Years album) (2015)
 * Communion (Park Jiha album) (2016)
 * "Communion", a Raffi album (2009)
 * "Communion", a song by Debbie Harry from Debravation
 * "Communion", a song by Third Day from Wherever You Are
 * Communion Music, an artist-led music community

title: Communion


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Calorie

The calorie is a unit of energy that originated from the caloric theory of heat. The large calorie, food calorie, dietary calorie, or kilogram calorie is defined as the amount of heat needed to raise the temperature of one liter of water by one degree Celsius (or one kelvin). The small calorie or gram calorie is defined as the amount of heat needed to cause the same increase in one milliliter of water. Thus, 1 large calorie is equal to 1000 small calories.

In nutrition and food science, the term calorie and the symbol cal may refer to the large unit or to the small unit in different regions of the world. It is generally used in publications and package labels to express the energy value of foods in per serving or per weight, recommended dietary caloric intake, metabolic rates, etc. Some authors recommend the spelling Calorie and the symbol Cal (both with a capital C) if the large calorie is meant, to avoid confusion; however, this convention is often ignored.

In physics and chemistry, the word calorie and its symbol usually refer to the small unit, the large one being called kilocalorie (kcal). However, the kcal is not officially part of the International System of Units (SI), and is regarded as obsolete, having been replaced in many uses by the SI derived unit of energy, the joule (J), or the kilojoule (kJ) for 1000 joules.

The precise equivalence between calories and joules has varied over the years, but in thermochemistry and nutrition it is now generally assumed that one (small) calorie (thermochemical calorie) is equal to exactly 4.184 J, and therefore one kilocalorie (one large calorie) is 4184 J or 4.184 kJ.

History
The term "calorie" comes. It was first introduced by Nicolas Clément, as a unit of heat energy, in lectures on experimental calorimetry during the years 1819–1824. This was the "large" calorie. The term (written with lowercase "c") entered French and English dictionaries between 1841 and 1867.

The same term was used for the "small" unit by Pierre Antoine Favre (chemist) and Johann T. Silbermann (physicist) in 1852. This unit was used by U.S. physician Joseph Howard Raymond, in his classic 1894 textbook A Manual of Human Physiology. He proposed calling the "large" unit "kilocalorie", but the term did not catch on until some years later.

In 1879, Marcellin Berthelot distinguished between gram-calorie and kilogram-calorie, and proposed using "Calorie", with capital "C", for the large unit. This usage was adopted by Wilbur Olin Atwater, a professor at Wesleyan University, in 1887, in an influential article on the energy content of food.

The small calorie (cal) was recognized as a unit of the CGS system in 1896, alongside the already-existing CGS unit of energy, the erg (first suggested by Clausius in 1864, under the name ergon, and officially adopted in 1882).

In 1928, there were already serious complaints about the possible confusion arising from the two main definitions of the calorie and whether the notion of using the capital letter to distinguish them was sound.

The joule was the officially adopted SI unit of energy at the ninth General Conference on Weights and Measures in 1948. The calorie was mentioned in the 7th edition of the SI brochure as an example of a non-SI unit.

The alternate spelling is a less-common, non-standard variant.

Definitions
The "small" calorie is broadly defined as the amount of energy needed to increase the temperature of 1 gram of water by 1 °C (or 1 K, which is the same increment, a gradation of one percent of the interval between the melting point and the boiling point of water). The actual amount of energy required to accomplish this temperature increase depends on the atmospheric pressure and the starting temperature; different choices of these parameters have resulted in several different precise definitions of the unit.

The two definitions most common in older literature appear to be the 15 °C calorie and the thermochemical calorie. Until 1948, the latter was defined as 4.1833 international joules; the current standard of 4.184 J was chosen to have the new thermochemical calorie represent the same quantity of energy as before.

Nutrition
In the United States, in a nutritional context, the "large" unit is used almost exclusively. It is generally written "calorie" with lowercase "c" and symbol "cal", even in government publications. The SI unit kilojoule (kJ) may be used instead, in legal or scientific contexts. Most American nutritionists prefer the unit kilocalorie to the unit kilojoules, whereas most physiologists prefer to use kilojoules. In the majority of other countries, nutritionists prefer the kilojoule to the kilocalorie.

In the European Union, on nutrition facts labels, energy is expressed in both kilojoules and kilocalories, abbreviated as "kJ" and "kcal" respectively.

In China, only kilojoules are given.

Food energy
The unit is most commonly used to express food energy, namely the specific energy (energy per mass) of metabolizing different types of food. For example, fat (triglyceride lipids) contains 9 kilocalories per gram (kcal/g), while carbohydrates (sugar and starch) and protein contain approximately 4 kcal/g. Alcohol in food contains 7 kcal/g. The "large" unit is also used to express recommended nutritional intake or consumption, as in "calories per day".

Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on reducing caloric intake, different kinds of calorie-reduced diets have been shown to be generally effective.

Chemistry and physics
In other scientific contexts, the term "calorie" and the symbol "cal" almost always refers to the small unit; the "large" unit being generally called "kilocalorie" with symbol "kcal". It is mostly used to express the amount of energy released in a chemical reaction or phase change, typically per mole of substance, as in kilocalories per mole. It is also occasionally used to specify other energy quantities that relate to reaction energy, such as enthalpy of formation and the size of activation barriers. However, it is increasingly being superseded by the SI unit, the joule (J); and metric multiples thereof, such as the kilojoule (kJ).

The lingering use in chemistry is largely due to the fact that the energy released by a reaction in aqueous solution, expressed in kilocalories per mole of reagent, is numerically close to the concentration of the reagent, in moles per liter, multiplied by the change in the temperature of the solution, in kelvin or degrees Celsius. However, this estimate assumes that the volumetric heat capacity of the solution is 1 kcal/L/K, which is not exact even for pure water.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Calorie


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Corona Australis

Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax.

Although fainter than its northern counterpart, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1. Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Lying alongside the Milky Way, Corona Australis contains one of the closest star-forming regions to the Solar System—a dusty dark nebula known as the Corona Australis Molecular Cloud, lying about 430 light years away. Within it are stars at the earliest stages of their lifespan. The variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly.

Name
The name of the constellation was entered as "Corona Australis" when the International Astronomical Union (IAU) established the 88 modern constellations in 1922. In 1932, the name was instead recorded as "Corona Austrina" when the IAU's commission on notation approved a list of four-letter abbreviations for the constellations. The four-letter abbreviations were repealed in 1955. The IAU presently uses "Corona Australis" exclusively.

Characteristics
Corona Australis is a small constellation bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CrA". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of four segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 17:58.3:0 and 19:19.0:0, while the declination coordinates are between −36.77° and −45.52°. Covering 128 square degrees, Corona Australis culminates at midnight around the 30th of June and ranks 80th in area. Only visible at latitudes south of 53° north, Corona Australis cannot be seen from the British Isles as it lies too far south, but it can be seen from southern Europe and readily from the southern United States.

Features
While not a bright constellation, Corona Australis is nonetheless distinctive due to its easily identifiable pattern of stars, which has been described as horseshoe- or oval-shaped. Though it has no stars brighter than 4th magnitude, it still has 21 stars visible to the unaided eye (brighter than magnitude 5.5). Nicolas Louis de Lacaille used the Greek letters Alpha through to Lambda to label the most prominent eleven stars in the constellation, designating two stars as Eta and omitting Iota altogether. Mu Coronae Australis, a yellow star of spectral type G5.5III and apparent magnitude 5.21, was labelled by Johann Elert Bode and retained by Benjamin Gould, who deemed it bright enough to warrant naming.

Stars
The only star in the constellation to have received a name is Alfecca Meridiana or Alpha CrA. The name combines the Arabic name of the constellation with the Latin for "southern". In Arabic, Alfecca means "break", and refers to the shape of both Corona Australis and Corona Borealis. Also called simply "Meridiana", it is a white main sequence star located 125 light years away from Earth, with an apparent magnitude of 4.10 and spectral type A2Va. A rapidly rotating star, it spins at almost 200 km per second at its equator, making a complete revolution in around 14 hours. Like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It is currently a main-sequence star, but will eventually evolve into a white dwarf; currently, it has a luminosity 31 times greater, and a radius and mass of 2.3 times that of the Sun. Beta Coronae Australis is an orange giant 474 light years from Earth. Its spectral type is K0II, and it is of apparent magnitude 4.11. Since its formation, it has evolved from a B-type star to a K-type star. Its luminosity class places it as a bright giant; its luminosity is 730 times that of the Sun, designating it one of the highest-luminosity K0-type stars visible to the naked eye. 100 million years old, it has a radius of 43 solar radii and a mass of between 4.5 and 5 solar masses. Alpha and Beta are so similar as to be indistinguishable in brightness to the naked eye.

Some of the more prominent double stars include Gamma Coronae Australis—a pair of yellowish white stars 58 light years away from Earth, which orbit each other every 122 years. Widening since 1990, the two stars can be seen as separate with a 100 mm aperture telescope; they are separated by 1.3 arcseconds at an angle of 61 degrees. They have a combined visual magnitude of 4.2; each component is an F8V dwarf star with a magnitude of 5.01. Epsilon Coronae Australis is an eclipsing binary belonging to a class of stars known as W Ursae Majoris variables. These star systems are known as contact binaries as the component stars are so close together they touch. Varying by a quarter of a magnitude around an average apparent magnitude of 4.83 every seven hours, the star system lies 98 light years away. Its spectral type is F4VFe-0.8+. At the southern end of the crown asterism are the stars Eta1 and Eta2 CrA, which form an optical double. Of magnitude 5.1 and 5.5, they are separable with the naked eye and are both white. Kappa Coronae Australis is an easily resolved optical double—the components are of apparent magnitudes 6.3 and 5.6 and are about 1000 and 150 light years away respectively. They appear at an angle of 359 degrees, separated by 21.6 arcseconds. Kappa2 is actually the brighter of the pair and is more bluish white, with a spectral type of B9V, while Kappa1 is of spectral type A0III. Lying 202 light years away, Lambda Coronae Australis is a double splittable in small telescopes. The primary is a white star of spectral type A2Vn and magnitude of 5.1, while the companion star has a magnitude of 9.7. The two components are separated by 29.2 arcseconds at an angle of 214 degrees.

Zeta Coronae Australis is a rapidly rotating main sequence star with an apparent magnitude of 4.8, 221.7 light years from Earth. The star has blurred lines in its hydrogen spectrum due to its rotation. Its spectral type is B9V. Theta Coronae Australis lies further to the west, a yellow giant of spectral type G8III and apparent magnitude 4.62. Corona Australis harbours RX J1856.5-3754, an isolated neutron star that is thought to lie 140 (±40) parsecs, or 460 (±130) light years, away, with a diameter of 14 km. It was once suspected to be a strange star, but this has been discounted.

Corona Australis Molecular Cloud
The Corona Australis Molecular Cloud is a dark molecular cloud just north of Beta Coronae Australis. Illuminated by a number of embedded reflection nebulae the cloud fans out from Epsilon Coronae Australis eastward along the constellation border with Sagittarius. It contains, Herbig–Haro objects (protostars) and some very young stars, being one of the closest star-forming regions, 430 light years (130 parsecs) to the Solar System, at the surface of the Local Bubble. The first nebulae of the cloud were recorded in 1865 by Johann Friedrich Julius Schmidt.

Between Epsilon and Gamma Coronae Australis the cloud consists of the particular dark nebula and star forming region Bernes 157. It is 55 by 18 arcminutes wide and possesses several stars around magnitude 13. These stars are dimmed by up to 8 magnitudes because of the obscuring dust clouds. At the center of the active star-forming region lies the Coronet cluster (also called R CrA Cluster), which is used in studying star and protoplanetary disk formation. R Coronae Australis (R CrA) is an irregular variable star ranging from magnitudes 9.7 to 13.9. Blue-white, it is of spectral type B5IIIpe. A very young star, it is still accumulating interstellar material. It is obscured by, and illuminates, the surrounding nebula, NGC 6729, which brightens and darkens with it. The nebula is often compared to a comet for its appearance in a telescope, as its length is five times its width. Other stars of the cluster include S Coronae Australis, a G-class dwarf and T Tauri star.

Nearby north, another young variable star, TY Coronae Australis, illuminates another nebula: reflection nebula NGC 6726/NGC 6727. TY Coronae Australis ranges irregularly between magnitudes 8.7 and 12.4, and the brightness of the nebula varies with it. Blue-white, it is of spectral type B8e. The largest young stars in the region, R, S, T, TY and VV Coronae Australis, are all ejecting jets of material which cause surrounding dust and gas to coalesce and form Herbig–Haro objects, many of which have been identified nearby.

Not part of it is the globular cluster known as NGC 6723, which can be seen adjacent to the nebulosity in the neighbouring constellation of Sagittarius, but is much much further away.

Deep sky objects
IC 1297 is a planetary nebula of apparent magnitude 10.7, which appears as a green-hued roundish object in higher-powered amateur instruments. The nebula surrounds the variable star RU Coronae Australis, which has an average apparent magnitude of 12.9 and is a WC class Wolf–Rayet star. IC 1297 is small, at only 7 arcseconds in diameter; it has been described as "a square with rounded edges" in the eyepiece, elongated in the north–south direction. Descriptions of its color encompass blue, blue-tinged green, and green-tinged blue.

Corona Australis' location near the Milky Way means that galaxies are uncommonly seen. NGC 6768 is a magnitude 11.2 object 35′ south of IC 1297. It is made up of two galaxies merging, one of which is an elongated elliptical galaxy of classification E4 and the other a lenticular galaxy of classification S0. IC 4808 is a galaxy of apparent magnitude 12.9 located on the border of Corona Australis with the neighbouring constellation of Telescopium and 3.9 degrees west-southwest of Beta Sagittarii. However, amateur telescopes will only show a suggestion of its spiral structure. It is 1.9 arcminutes by 0.8 arcminutes. The central area of the galaxy does appear brighter in an amateur instrument, which shows it to be tilted northeast–southwest.

Southeast of Theta and southwest of Eta lies the open cluster ESO 281-SC24, which is composed of the yellow 9th magnitude star GSC 7914 178 1 and five 10th to 11th magnitude stars. Halfway between Theta Coronae Australis and Theta Scorpii is the dense globular cluster NGC 6541. Described as between magnitude 6.3 and magnitude 6.6, it is visible in binoculars and small telescopes. Around 22000 light years away, it is around 100 light years in diameter. It is estimated to be around 14 billion years old. NGC 6541 appears 13.1 arcminutes in diameter and is somewhat resolvable in large amateur instruments; a 12-inch telescope reveals approximately 100 stars but the core remains unresolved.

Meteor showers
The Corona Australids are a meteor shower that takes place between 14 and 18 March each year, peaking around 16 March. This meteor shower does not have a high peak hourly rate. In 1953 and 1956, observers noted a maximum of 6 meteors per hour and 4 meteors per hour respectively; in 1955 the shower was "barely resolved". However, in 1992, astronomers detected a peak rate of 45 meteors per hour. The Corona Australids' rate varies from year to year. At only six days, the shower's duration is particularly short, and its meteoroids are small; the stream is devoid of large meteoroids. The Corona Australids were first seen with the unaided eye in 1935 and first observed with radar in 1955. Corona Australid meteors have an entry velocity of 45 kilometers per second. In 2006, a shower originating near Beta Coronae Australis was designated as the Beta Coronae Australids. They appear in May, the same month as a nearby shower known as the May Microscopids, but the two showers have different trajectories and are unlikely to be related.

History

Corona Australis may have been recorded by ancient Mesopotamians in the MUL.APIN, as a constellation called MA.GUR ("The Bark"). However, this constellation, adjacent to SUHUR.MASH ("The Goat-Fish", modern Capricornus), may instead have been modern Epsilon Sagittarii. As a part of the southern sky, MA.GUR was one of the fifteen "stars of Ea".

In the 3rd century BC, the Greek didactic poet Aratus wrote of, but did not name the constellation, instead calling the two crowns Στεφάνοι (Stephanoi). The Greek astronomer Ptolemy described the constellation in the 2nd century AD, though with the inclusion of Alpha Telescopii, since transferred to Telescopium. Ascribing 13 stars to the constellation, he named it Στεφάνος νοτιος (Stephanos notios), "Southern Wreath", while other authors associated it with either Sagittarius (having fallen off his head) or Centaurus; with the former, it was called Corona Sagittarii. Similarly, the Romans called Corona Australis the "Golden Crown of Sagittarius". It was known as Parvum Coelum ("Canopy", "Little Sky") in the 5th century. The 18th-century French astronomer Jérôme Lalande gave it the names Sertum Australe ("Southern Garland") and Orbiculus Capitis, while German poet and author Philippus Caesius called it Corolla ("Little Crown") or Spira Australis ("Southern Coil"), and linked it with the Crown of Eternal Life from the New Testament. Seventeenth-century celestial cartographer Julius Schiller linked it to the Diadem of Solomon. Sometimes, Corona Australis was not the wreath of Sagittarius but arrows held in his hand.

Corona Australis has been associated with the myth of Bacchus and Stimula. Jupiter had impregnated Stimula, causing Juno to become jealous. Juno convinced Stimula to ask Jupiter to appear in his full splendor, which the mortal woman could not handle, causing her to burn. After Bacchus, Stimula's unborn child, became an adult and the god of wine, he honored his deceased mother by placing a wreath in the sky.

In Chinese astronomy, the stars of Corona Australis are located within the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ). The constellation itself was known as ti'en pieh ("Heavenly Turtle") and during the Western Zhou period, marked the beginning of winter. However, precession over time has meant that the "Heavenly River" (Milky Way) became the more accurate marker to the ancient Chinese and hence supplanted the turtle in this role. Arabic names for Corona Australis include Al Ķubbah "the Tortoise", Al Ĥibā "the Tent" or Al Udḥā al Na'ām "the Ostrich Nest". It was later given the name Al Iklīl al Janūbiyyah, which the European authors Chilmead, Riccioli and Caesius transliterated as Alachil Elgenubi, Elkleil Elgenubi and Aladil Algenubi respectively.

The ǀXam speaking San people of South Africa knew the constellation as ≠nabbe ta !nu "house of branches"—owned originally by the Dassie (rock hyrax), and the star pattern depicting people sitting in a semicircle around a fire.

The indigenous Boorong people of northwestern Victoria saw it as Won, a boomerang thrown by Totyarguil (Altair). The Aranda people of Central Australia saw Corona Australis as a coolamon carrying a baby, which was accidentally dropped to earth by a group of sky-women dancing in the Milky Way. The impact of the coolamon created Gosses Bluff crater, 175 km west of Alice Springs. The Torres Strait Islanders saw Corona Australis as part of a larger constellation encompassing part of Sagittarius and the tip of Scorpius's tail; the Pleiades and Orion were also associated. This constellation was Tagai's canoe, crewed by the Pleiades, called the Usiam, and Orion, called the Seg. The myth of Tagai says that he was in charge of this canoe, but his crewmen consumed all of the supplies onboard without asking permission. Enraged, Tagai bound the Usiam with a rope and tied them to the side of the boat, then threw them overboard. Scorpius's tail represents a suckerfish, while Eta Sagittarii and Theta Corona Australis mark the bottom of the canoe. On the island of Futuna, the figure of Corona Australis was called Tanuma and in the Tuamotus, it was called Na Kaua-ki-Tonga.

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Corcovado

Corcovado which means "hunchback" in Portuguese, is a mountain in central Rio de Janeiro, Brazil. It is a 710 m granite peak located in the Tijuca Forest, a national park.

Corcovado hill lies just west of the city center but is wholly within the city limits and visible from great distances. It is known worldwide for the statue of Jesus atop its peak, entitled Christ the Redeemer.

Access
The peak and statue can be reached via a narrow road, by the 3.8 km Corcovado Rack Railway, which was opened in 1884 and refurbished in 1980, or by the walking trail on the south side of the mountain that starts from Parque Lage. The railway uses three electrically powered trains, with a capacity of 540 passengers per hour. The rail trip takes approximately 20 minutes and departs every 20 minutes. Due to its limited passenger capacity, the wait to board at the entry station can take several hours. The year-round schedule is 8:30 to 18:30.

From the train terminus and road, the observation deck at the foot of the statue is reached by 223 steps, or by elevators and escalators. Among the most popular year-round tourist attractions in Rio de Janeiro, the Corcovado railway, access roads, and statue platform are commonly crowded.

Attractions
Corcovado's most popular attraction is the 38 m statue depicting Jesus at its peak, entitled Christ the Redeemer (Cristo Redentor), and the viewing platform at its peak, drawing over 300,000 visitors per year. The statue was constructed from 1922 to 1931. From the peak's platform the panoramic view includes downtown Rio de Janeiro, Sugarloaf Mountain, the Rodrigo de Freitas lagoon, Copacabana and Ipanema beaches, Maracanã Stadium, and several of Rio de Janeiro's favelas. Cloud cover is common in Rio and the view from the platform is often obscured. Sunny days are recommended for optimal viewing.

Notable past visitors to the mountain peak include Charles Darwin, Pope Pius XII, Pope John Paul II, Alberto Santos-Dumont, Albert Einstein, Diana, Princess of Wales, and General Sherman, among others. An additional attraction of the mountain is rock climbing. The south face had 54 climbing routes in 1992. The easiest way starts from Parque Lage.

Geology
The peak of Corcovado is a big granite dome, which describes a generally vertical rocky formation. It is claimed to be the highest such formation in Brazil, the second highest being Pedra Agulha, situated near the town of Pancas in Espírito Santo.

References in Brazilian culture
Corcovado is considered an icon of Brazilian culture. Corcovado is a 1960 bossa nova song and jazz standard by Antônio Carlos Jobim whose lyrics draw on images of the hill. Corcovado has also been referenced in other artistic works (e.g. the lyrics of Ben Harper, literary works, films, etc.).

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Cheddar, Somerset

Cheddar is a large village and civil parish in the English county of Somerset. It is situated on the southern edge of the Mendip Hills, 9 mi north-west of Wells, 11 mi south-east of Weston-super-Mare and 18 mi south-west of Bristol. The civil parish includes the hamlets of Nyland and Bradley Cross. The parish had a population of 5,755 in 2011 and an acreage of 8592 acres as of 1961.

Cheddar Gorge, on the northern edge of the village, is the largest gorge in the United Kingdom and includes several show caves, including Gough's Cave. The gorge has been a centre of human settlement since Neolithic times, including a Saxon palace. It has a temperate climate and provides a unique geological and biological environment that has been recognised by the designation of several Sites of Special Scientific Interest. It is also the site of several limestone quarries. The village gave its name to Cheddar cheese and has been a centre for strawberry growing. The crop was formerly transported on the Cheddar Valley rail line, which closed in the late 1960s and is now a cycle path. The village is now a major tourist destination with several cultural and community facilities, including the Cheddar Show Caves Museum.

The village supports a variety of community groups including religious, sporting and cultural organisations. Several of these are based on the site of the Kings of Wessex Academy, which is the largest educational establishment.

History
The name Cheddar comes from the Old English word ceodor, meaning deep dark cavity or pouch.

There is evidence of occupation from the Neolithic period in Cheddar. Britain's oldest complete human skeleton, Cheddar Man, estimated to be 9,000 years old, was found in Cheddar Gorge in 1903. Older remains from the Upper Late Palaeolithic era (12,000–13,000 years ago) have been found. There is some evidence of a Bronze Age field system at the Batts Combe quarry site. There is also evidence of Bronze Age barrows at the mound in the Longwood valley, which if man-made it is likely to be a field system. The remains of a Roman villa have been excavated in the grounds of the current vicarage.

The village of Cheddar had been important during the Roman and Saxon eras. There was a royal palace at Cheddar during the Saxon period, which was used on three occasions in the 10th century to host the Witenagemot. The ruins of the palace were excavated in the 1960s. They are located on the grounds of the Kings of Wessex Academy, together with a 14th-century chapel dedicated to St. Columbanus. Roman remains have also been uncovered at the site. Cheddar was listed in the Domesday Book of 1086 as Ceder, meaning "Shear Water", from the Old English scear and Old Welsh dŵr. An alternative spelling in earlier documents, common through the 1850s is Chedder.

As early as 1130 AD, the Cheddar Gorge was recognised as one of the "Four wonders of England". Historically, Cheddar's source of wealth was farming and cheese making for which it was famous as early as 1170 AD. The parish was part of the Winterstoke Hundred.

The manor of Cheddar was deforested in 1337 and Bishop Ralph was granted a licence by the King to create a hunting forest.

As early as 1527 there are records of watermills on the river. In the 17th and 18th centuries, there were several watermills which ground corn and made paper, with 13 mills on the Yeo at the peak, declining to seven by 1791 and just three by 1915. In the Victorian era it also became a centre for the production of clothing. The last mill, used as a shirt factory, closed in the early 1950s.

William Wilberforce saw the poor conditions of the locals when he visited Cheddar in 1789. He inspired Hannah More in her work to improve the conditions of the Mendip miners and agricultural workers. In 1801, 4400 acre of common land were enclosed under the Inclosure Acts.

Tourism of the Cheddar gorge and caves began with the opening of the Cheddar Valley Railway in 1869.

Cheddar, its surrounding villages and specifically the gorge has been subject to flooding. In the Chew Stoke flood of 1968 the flow of water washed large boulders down the gorge, washed away cars, and damaged the cafe and the entrance to Gough's Cave.

Government
Cheddar is recognised as a village. The adjacent settlement of Axbridge, although only about a third the population of Cheddar, is a town. This apparently illogical situation is explained by the relative importance of the two places in historic times. While Axbridge grew in importance as a centre for cloth manufacturing in the Tudor period and gained a charter from King John, Cheddar remained a more dispersed mining and dairy-farming village. Its population grew with the arrival of the railways in the Victorian era and the advent of tourism.

The parish council, which has 15 members who are elected for four years, is responsible for local issues, including setting an annual precept (local rate) to cover the council's operating costs and producing annual accounts for public scrutiny. The parish council evaluates local planning applications and works with the police, district council officers, and neighbourhood watch groups on matters of crime, security, and traffic. The parish council's role also includes initiating projects for the maintenance and repair of parish facilities, as well as consulting with the district council on the maintenance, repair, and improvement of highways, drainage, footpaths, public transport, and street cleaning. Conservation matters (including trees and listed buildings) and environmental issues are also the responsibility of the council.

The village is in the 'Cheddar and Shipham' electoral ward. After including Shipham the total population of the ward taken at the 2011 census is 6,842.

For local government purposes, since 1 April 2023, the village comes under the unitary authority of Somerset Council. Prior to this, it was part of the non-metropolitan district of Sedgemoor, which was formed on 1 April 1974 under the Local Government Act 1972, having previously been part of Axbridge Rural District. Fire, police and ambulance services are provided jointly with other authorities through the Devon and Somerset Fire and Rescue Service, Avon and Somerset Constabulary and the South Western Ambulance Service.

It is also part of the Wells and Mendip Hills county constituency represented in the House of Commons of the Parliament of the United Kingdom. It elects one Member of Parliament (MP) by the first past the post system of election. Prior to Brexit in 2020, it was part of the South West England constituency of the European Parliament.

International relations
Cheddar is twinned with Felsberg, Germany and Vernouillet, France, and it has an active programme of exchange visits. Initially, Cheddar twinned with Felsberg in 1984. In 2000, Cheddar twinned with Vernouillet, which had also been twinned with Felsberg. Cheddar also has a friendship link with Ocho Rios in Saint Ann Parish, Jamaica.

It is also twinned with the commune of Descartes in the Indre-et-Loire department.

Geography

The area is underlain by Black Rock slate, Burrington Oolite and Clifton Down Limestone of the Carboniferous Limestone Series, which contain ooliths and fossil debris on top of Old Red Sandstone, and by Dolomitic Conglomerate of the Keuper. Evidence for Variscan orogeny is seen in the sheared rock and cleaved shales. In many places weathering of these strata has resulted in the formation of immature calcareous soils.

Gorge and caves
Cheddar Gorge, which is located on the edge of the village, is the largest gorge in the United Kingdom. The gorge is the site of the Cheddar Caves, where Cheddar Man was found in 1903. Older remains from the Upper Late Palaeolithic era (12,000–13,000 years ago) have been found. The caves, produced by the activity of an underground river, contain stalactites and stalagmites. Gough's Cave, which was discovered in 1903, leads around 400 m into the rock-face, and contains a variety of large rock chambers and formations. Cox's Cave, discovered in 1837, is smaller but contains many intricate formations. A further cave houses a children's entertainment walk known as the "Crystal Quest".

Cheddar Gorge, including Cox's Cave, Gough's Cave and other attractions, has become a tourist destination, attracting about 500,000 visitors per year. In a 2005 poll of Radio Times readers, following its appearance on the 2005 television programme Seven Natural Wonders, Cheddar Gorge was named as the second greatest natural wonder in Britain, surpassed only by the Dan yr Ogof caves.

Sites of Special Scientific Interest
There are several large and unique Sites of Special Scientific Interest (SSSI) around the village.

Cheddar Reservoir is a near-circular artificial reservoir operated by Bristol Water. Dating from the 1930s, it has a capacity of 135 million gallons (614,000 cubic metres). The reservoir is supplied with water taken from the Cheddar Yeo, which rises in Gough's Cave in Cheddar Gorge and is a tributary of the River Axe. The inlet grate for the 54 in water pipe that is used to transport the water can be seen next to the sensory garden in Cheddar Gorge. It has been designated as a Site of Special Scientific Interest (SSSI) due to its wintering waterfowl populations.

Cheddar Wood and the smaller Macall's Wood form a biological Site of Special Scientific Interest from what remains of the wood of the Bishops of Bath and Wells in the 13th century and of King Edmund the Magnificent's wood in the 10th. During the 19th century, its lower fringes were grubbed out to make strawberry fields. Most of these have been allowed to revert to woodland. The wood was coppiced until 1917. This site compromises a wide range of habitats which include ancient and secondary semi-natural broadleaved woodland, unimproved neutral grassland, and a complex mosaic of calcareous grassland and acidic dry dwarf-shrub heath. Cheddar Wood is one of only a few English stations for starved wood-sedge (Carex depauperata). Purple gromwell (Lithospermum purpurocaeruleum), a nationally rare plant, also grows in the wood. Butterflies include silver-washed fritillary (Argynnis paphia), dark green fritillary (Argynnis aglaja), pearl-bordered fritillary (Boloria euphrosyne), holly blue (Celastrina argiolus) and brown argus (Aricia agestis). The slug Arion fasciatus, which has a restricted distribution in the south of England, and the soldier beetle Cantharis fusca also occur.

By far the largest of the SSSIs is called Cheddar Complex and covers 441.3 ha of the gorge, caves and the surrounding area. It is important because of both biological and geological features. It includes four SSSIs, formerly known as Cheddar Gorge SSSI, August Hole/Longwood Swallet SSSI, GB Cavern Charterhouse SSSI and Charterhouse on-Mendip SSSI. It is partly owned by the National Trust who acquired it in 1910 and partly managed by the Somerset Wildlife Trust.

Quarries
Close to the village and gorge are Batts Combe quarry and Callow Rock quarry, two of the active Quarries of the Mendip Hills where limestone is still extracted. Operating since the early 20th century, Batts Combe is owned and operated by Hanson Aggregates. The output in 2005 was around 4,000 tonnes of limestone per day, one third of which was supplied to an on-site lime kiln, which closed in 2009; the remainder was sold as coated or dusted aggregates. The limestone at this site is close to 99 percent carbonate of calcium and magnesium (dolomite).

The Chelmscombe Quarry finished its work as a limestone quarry in the 1950s and was then used by the Central Electricity Generating Board as a tower testing station. During the 1970s and 1980s it was also used to test the ability of containers of radioactive material to withstand impacts and other accidents.

Climate
Along with the rest of South West England, Cheddar has a temperate climate which is generally wetter and milder than the rest of the country. The annual mean temperature is approximately 10 °C. Seasonal temperature variation is less extreme than most of the United Kingdom because of the adjacent sea, which moderates temperature. The summer months of July and August are the warmest with mean daily maxima of approximately 21 °C. In winter mean minimum temperatures of 1 or are common. In the summer the Azores high-pressure system affects the south-west of England. Convective cloud sometimes forms inland, reducing the number of hours of sunshine; annual sunshine rates are slightly less than the regional average of 1,600 hours. Most of the rainfall in the south-west is caused by Atlantic depressions or by convection. Most of the rainfall in autumn and winter is caused by the Atlantic depressions, which are most active during those seasons. In summer, a large proportion of the rainfall is caused by sun heating the ground leading to convection and to showers and thunderstorms. Average rainfall is around 700 mm. About 8–15 days of snowfall per year is typical. November to March have the highest mean wind speeds, and June to August have the lightest winds. The predominant wind direction is from the south-west.

Demography
The parish has a population in 2011 of 5,093, with a mean age of 43 years. Residents lived in 2,209 households. The vast majority of households (2,183) gave their ethnic status at the 2001 census as white.

2021 census
According to the most recent 2021 census, the village had a total population of 6,263 with 51.1% female and 48.9% male. Over 6,101 people or 97.3% identified as white, 1% (61) Asian, 0.3% (17) Black and 1.3% (79) as mixed.

The most common places of birth were: 94.1% or 5,900 born in the United Kingdom and 2.5% (156) born in the European Union, 81 Africa and 65 Middle East and Asia, 29 Americas and Caribbean.

Economy
The village gave its name to Cheddar cheese, which is the most popular type of cheese in the United Kingdom. The cheese is now made and consumed worldwide, and only one producer remains in the village.

Since the 1880s, Cheddar's other main produce has been the strawberry, which is grown on the south-facing lower slopes of the Mendip hills. As a consequence of its use for transporting strawberries to market, the since-closed Cheddar Valley line became known as The Strawberry Line after it opened in 1869. The line ran from Yatton to Wells. When the rest of the line was closed and all passenger services ceased, the section of the line between Cheddar and Yatton remained open for goods traffic. It provided a fast link with the main markets for the strawberries in Birmingham and London, but finally closed in 1964, becoming part of the Cheddar Valley Railway Nature Reserve.

Cheddar Ales is a small brewery based in the village, producing beer for local public houses.

Tourism is a significant source of employment. Around 15 percent of employment in Sedgemoor is provided by tourism, but within Cheddar it is estimated to employ as many as 1,000 people. The village also has a youth hostel, and a number of camping and caravan sites.

Culture and community
Cheddar has a number of active service clubs including Cheddar Vale Lions Club, Mendip Rotary and Mendip Inner Wheel Club. The clubs raise money for projects in the local community and hold annual events such as a fireworks display, duck races in the Gorge, a dragon boat race on the reservoir and concerts on the grounds of the nearby St Michael's Cheshire Home.

Several notable people have been born or lived in Cheddar. Musician Jack Bessant, the bass guitarist with the band Reef grew up on his parents' strawberry farm, and Matt Goss and Luke Goss, former members of Bros, lived in Cheddar for nine months as children. Trina Gulliver, ten-time World Professional Darts Champion, previously lived in Cheddar until 2017. The comedian Richard Herring grew up in Cheddar. His 2008 Edinburgh Festival Fringe show, The Headmaster's Son is based on his time at The Kings of Wessex School, where his father Keith was the headmaster. The final performance of this show was held at the school in November 2009. He also visited the school in March 2010 to perform his show Hitler Moustache. In May 2013, a community radio station called Pulse was launched.

Landmarks
The market cross in Bath Street dates from the 15th century, with the shelter having been rebuilt in 1834. It has a central octagonal pier, a socket raised on four steps, a hexagonal shelter with six arched four-centred openings, shallow two-stage buttresses at each angle, and an embattled parapet. The shaft is crowned by an abacus with figures in niches, probably from the late 19th century, although the cross is now missing. It was rebuilt by Thomas, Marquess of Bath. It is a scheduled monument (Somerset County No 21) and Grade II* listed building.

In January 2000, the cross was seriously damaged in a traffic accident. By 2002, the cross had been rebuilt and the area around it was redesigned to protect and enhance its appearance. The cross was badly damaged again in March 2012, when a taxi crashed into it late at night demolishing two sides. Repair work, which included the addition of wooden-clad steel posts to protect against future crashes, was completed in November 2012 at a cost of £60,000.

Hannah More, a philanthropist and educator, founded a school in the village in the late 18th century for the children of miners. Her first school was located in a 17th-century house. Now named "Hannah More's Cottage", the Grade II-listed building is used by the local community as a meeting place.

Transport
The village is situated on the A371 road which runs from Wincanton, to Weston-super-Mare. It is approximately 5 mi from the route of the M5 motorway with around a 10 mi drive to junction 22.

It was on the Cheddar Valley line, a railway line that was opened in 1869 and closed in 1963. It became known as The Strawberry Line because of the large volume of locally-grown strawberries that it carried. It ran from Yatton railway station through Cheddar to Wells (Tucker Street) railway station and joined the East Somerset Railway to make a through route via Shepton Mallet (High Street) railway station to Witham. Sections of the now-disused railway have been opened as the Strawberry Line Trail, which currently runs from Yatton to Cheddar. The Cheddar Valley line survived until the "Beeching Axe". Towards the end of its life there were so few passengers that diesel railcars were sometimes used. The Cheddar branch closed to passengers on 9 September 1963 and to goods in 1964. The line closed in the 1960s, when it became part of the Cheddar Valley Railway Nature Reserve, and part of the National Cycle Network route 26. The cycle route also intersects with the West Mendip Way and various other footpaths.

The principal bus route is the hourly service 126 between Weston-super-Mare and Wells operated by First West of England. Other bus routes include the service 668 from Shipham to Street which runs every couple of hours operated by Libra Travel, as well as the college bus service 66 which runs from Axbridge to the Bridgwater Campus of Bridgwater and Taunton College in the mornings and evenings of college term times, and is operated by Bakers Dolphin.

Education
The first school in Cheddar was set up by Hannah More during the 18th Century, however now Cheddar has three schools belonging to the Cheddar Valley Group of Schools, twelve schools that provide Cheddar Valley's three-tier education system. Cheddar First School has ten classes for children between 4 and 9 years. Fairlands Middle School, a middle school categorised as a middle-deemed-secondary school, has 510 pupils between 9 and 13. Fairlands takes children moving up from Cheddar First School as well as other first schools in the Cheddar Valley. The Kings of Wessex Academy, a coeducational comprehensive school, has been rated as "good" by Ofsted. It has 1,176 students aged 13 to 18, including 333 in the sixth form. Kings is a faith school linked to the Church of England. It was awarded the specialist status of Technology College in 2001, enabling it to develop its Information Technology (IT) facilities and improve courses in science, mathematics and design technology. In 2007 it became a foundation school, giving it more control over its own finances. The academy owns and runs a sports centre and swimming pool, Kings Fitness & Leisure, with facilities that are used by students as well as residents. It has since November 2016 been a part of the Wessex Learning Trust which incorporates eight academies from the surrounding area.

Religious sites
The Church of St Andrew dates from the 14th century. It was restored in 1873 by William Butterfield. It is a Grade I listed building and contains some 15th-century stained glass and an altar table of 1631. The chest tomb in the chancel is believed to contain the remains of Sir Thomas Cheddar and is dated 1442. The tower, which rises to 100 ft, contains a bell dating from 1759 made by Thomas Bilbie of the Bilbie family. The graveyard contains the grave of the hymn writer William Chatterton Dix.

There are also churches for Roman Catholic, Methodist and other denominations, including Cheddar Valley Community Church, who not only meet at the Kings of Wessex School on Sunday, but also have their own site on Tweentown for meeting during the week. The Baptist chapel was built in 1831.

Sport
Kings Fitness & Leisure, situated on the grounds of the Kings of Wessex School, provides a venue for various sports and includes a 20-metre swimming pool, racket sport courts, a sports hall, dance studios and a gym. A youth sports festival was held on Sharpham Road Playing Fields in 2009. In 2010 a skatepark was built in the village, funded by the Cheddar Local Action Team.

Cheddar A.F.C., founded in 1892 and nicknamed "The Cheesemen", play in the Western Football League Division One. In 2009 plans were revealed to move the club from its present home at Bowdens Park on Draycott Road to a new larger site.

Cheddar Cricket Club was formed in the late 19th century and moved to Sharpham Road Playing Fields in 1964. They now play in the West of England Premier League Somerset Division. Cheddar Rugby Club, who own part of the Sharpham playing fields, was formed in 1836. The club organises an annual Cheddar Rugby Tournament. Cheddar Lawn Tennis Club, was formed in 1924, and play in the North Somerset League and also has social tennis and coaching. Cheddar Running Club organised an annual half marathon until 2009.

The village is both on the route of the West Mendip Way and Samaritans Way South West.

title: Cheddar, Somerset


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Compact disc

The compact disc (CD) is a digital optical disc data storage format that was codeveloped by Philips and Sony to store and play digital audio recordings. It uses the Compact Disc Digital Audio format which typically provides 74 minutes of audio on a disc. In later years, the compact disc was adapted for non-audio computer data storage purposes as CD-ROM and its derivatives. First released in Japan in October 1982, the CD was the second optical disc technology to be invented, after the much larger LaserDisc (LD). By 2007, 200 billion CDs (including audio CDs, CD-ROMs and CD-Rs) had been sold worldwide.

Standard CDs have a diameter of 120 mm, and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about of data. Capacity is routinely extended to 80 minutes and by arranging data more closely on the same-sized disc. The Mini CD has various diameters ranging from 60 to 80 mm; they have been used for CD singles or delivering device drivers.

The CD gained rapid popularity in the 1990s, quickly outselling all other audio formats in the United States by 1991, ending the market dominance of the phonograph record and the cassette tape. By 2000, the CD accounted for 92.3% of the entire market share in regard to US music sales. The CD is considered the last dominant audio format of the album era, as the rise of MP3, iTunes, cellular ringtones, and other downloadable music formats in the mid-2000s ended the decade-long dominance of the CD.

The Digital Audio format was later adapted (as CD-ROM) for general purpose data storage and initially could hold much more data than a personal computer hard disk drive. Several other formats were further derived, both pre-pressed and blank user writable, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video CD (VCD), Super Video CD (SVCD), Photo CD, Picture CD, Compact Disc-Interactive (CD-i), Enhanced Music CD, and Super Audio CD (SACD) which may have a CD-DA layer.

Physical details

A CD is made from 1.2 mm thick, polycarbonate plastic, and weighs 14–33 grams. From the center outward, components are: the center spindle hole (15 mm), the first-transition area (clamping ring), the clamping area (stacking ring), the second-transition area (mirror band), the program (data) area, and the rim. The inner program area occupies a radius from 25 to 58 mm.

A thin layer of aluminum or, more rarely, gold is applied to the surface, making it reflective. The metal is protected by a film of lacquer normally spin coated directly on the reflective layer. The label is printed on the lacquer layer, usually by screen printing or offset printing.

CD data is represented as tiny indentations known as pits, encoded in a spiral track molded into the top of the polycarbonate layer. The areas between pits are known as lands. Each pit is approximately 100 nm deep by 500 nm wide, and varies from 850 nm to 3.5 μm in length. The distance between the windings (the pitch) is 1.6 μm (measured center-to-center, not between the edges).

When playing an audio CD, a motor within the CD player spins the disc to a scanning velocity of 1.2–1.4 m/s (constant linear velocity, CLV)—equivalent to approximately 500 RPM at the inside of the disc, and approximately 200 RPM at the outside edge. The track on the CD begins at the inside and spirals outward so a disc played from beginning to end slows its rotation rate during playback.

The program area is 86.05 cm2 and the length of the recordable spiral is  With a scanning speed of 1.2 m/s, the playing time is 74 minutes or 650 MiB of data on a CD-ROM. A disc with data packed slightly more densely is tolerated by most players (though some old ones fail). Using a linear velocity of 1.2 m/s and a narrower track pitch of 1.5 μm increases the playing time to 80 minutes, and data capacity to 700 MiB. Even denser tracks are possible, with semi-standard 90 minute/800 MiB discs having 1.33 μm, and 99 minute/870 MiB having 1.26 μm, but compatibility suffers as density increases.

A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser through the bottom of the polycarbonate layer. The change in height between pits and lands results in a difference in the way the light is reflected. Because the pits are indented into the top layer of the disc and are read through the transparent polycarbonate base, the pits form bumps when read. The laser hits the disc, casting a circle of light wider than the modulated spiral track reflecting partially from the lands and partially from the top of any bumps where they are present. As the laser passes over a pit (bump), its height means that the round trip path of the light reflected from its peak is 1/2 wavelength out of phase with the light reflected from the land around it. This is because the height of a bump is around 1/4 of the wavelength of the light used, so the light falls 1/4 out of phase before reflection and another 1/4 wavelength out of phase after reflection. This causes partial cancellation of the laser's reflection from the surface. By measuring the reflected intensity change with a photodiode, a modulated signal is read back from the disc.

To accommodate the spiral pattern of data, the laser is placed on a mobile mechanism within the disc tray of any CD player. This mechanism typically takes the form of a sled that moves along a rail. The sled can be driven by a worm gear or linear motor. Where a worm gear is used, a second shorter-throw linear motor, in the form of a coil and magnet, makes fine position adjustments to track eccentricities in the disk at high speed. Some CD drives (particularly those manufactured by Philips during the 1980s and early 1990s) use a swing arm similar to that seen on a gramophone.

The pits and lands do not directly represent the 0s and 1s of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from either pit to land or land to pit indicates a 1, while no change indicates a series of 0s. There must be at least two, and no more than ten 0s between each 1, which is defined by the length of the pit. This, in turn, is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc. These encoding techniques (defined in the Red Book) were originally designed for CD Digital Audio, but they later became a standard for almost all CD formats (such as CD-ROM).

Integrity
CDs are susceptible to damage during handling and from environmental exposure. Pits are much closer to the label side of a disc, enabling defects and contaminants on the clear side to be out of focus during playback. Consequently, CDs are more likely to suffer damage on the label side of the disc. Scratches on the clear side can be repaired by refilling them with similar refractive plastic or by careful polishing. The edges of CDs are sometimes incompletely sealed, allowing gases and liquids to enter the CD and corrode the metal reflective layer and/or interfere with the focus of the laser on the pits, a condition known as disc rot. The fungus Geotrichum candidum has been found—under conditions of high heat and humidity—to consume the polycarbonate plastic and aluminium found in CDs.

The data integrity of compact discs can be measured using surface error scanning, which can measure the rates of different types of data errors, known as C1, C2, CU and extended (finer-grain) error measurements known as E11, E12, E21, E22, E31 and E32, of which higher rates indicate a possibly damaged or unclean data surface, low media quality, deteriorating media and recordable media written to by a malfunctioning CD writer.

Error scanning can reliably predict data losses caused by media deterioration. Support of error scanning differs between vendors and models of optical disc drives, and extended error scanning (known as "advanced error scanning" in Nero DiscSpeed) has only been available on Plextor and some BenQ optical drives so far, as of 2020.

Disc shapes and diameters

The digital data on a CD begins at the center of the disc and proceeds toward the edge, which allows adaptation to the different sizes available. Standard CDs are available in two sizes. By far, the most common is 120 mm in diameter, with a 74-, 80, 90, or 99-minute audio capacity and a 650, 700, 800, or 870 MiB (737,280,000-byte) data capacity. Discs are 1.2 mm thick, with a 15 mm center hole. The size of the hole was chosen by Joop Sinjou and based on a Dutch 10-cent coin: a dubbeltje. Philips/Sony patented the physical dimensions.

The official Philips history says the capacity was specified by Sony executive Norio Ohga to be able to contain the entirety of Beethoven's Ninth Symphony on one disc. This is a myth according to Kees Immink, as the EFM code format had not yet been decided in December 1979, when the 120 mm size was adopted. The adoption of EFM in June 1980 allowed 30 percent more playing time that would have resulted in 97 minutes for 120 mm diameter or 74 minutes for a disc as small as 100 mm. Instead, the information density was lowered by 30 percent to keep the playing time at 74 minutes. The 120 mm diameter has been adopted by subsequent formats, including Super Audio CD, DVD, HD DVD, and Blu-ray Disc. The 80 mm diameter discs ("Mini CDs") can hold up to 24 minutes of music or 210 MiB.

Audio CD

The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. The document is known colloquially as the Red Book CD-DA after the color of its cover. The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel. Four-channel sound was to be an allowable option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; thus, the mono source material is usually presented as two identical channels in a standard Red Book stereo track (i.e., mirrored mono); an MP3 CD, can have audio file formats with mono sound.

CD-Text is an extension of the Red Book specification for an audio CD that allows for the storage of additional text information (e.g., album name, song name, artist) on a standards-compliant audio CD. The information is stored either in the lead-in area of the CD, where there are roughly five kilobytes of space available or in the subcode channels R to W on the disc, which can store about 31 megabytes.

Compact Disc + Graphics is a special audio compact disc that contains graphics data in addition to the audio data on the disc. The disc can be played on a regular audio CD player, but when played on a special CD+G player, it can output a graphics signal (typically, the CD+G player is hooked up to a television set or a computer monitor); these graphics are almost exclusively used to display lyrics on a television set for karaoke performers to sing along with. The CD+G format takes advantage of the channels R through W. These six bits store the graphics information.

CD + Extended Graphics (CD+EG, also known as CD+XG) is an improved variant of the Compact Disc + Graphics (CD+G) format. Like CD+G, CD+EG uses basic CD-ROM features to display text and video information in addition to the music being played. This extra data is stored in subcode channels R-W. Very few, if any, CD+EG discs have been published.

Super Audio CD
Super Audio CD (SACD) is a high-resolution, read-only optical audio disc format that was designed to provide higher-fidelity digital audio reproduction than the Red Book. Introduced in 1999, it was developed by Sony and Philips, the same companies that created the Red Book. SACD was in a format war with DVD-Audio, but neither has replaced audio CDs. The SACD standard is referred to as the Scarlet Book standard.

Titles in the SACD format can be issued as hybrid discs; these discs contain the SACD audio stream as well as a standard audio CD layer which is playable in standard CD players, thus making them backward compatible.

CD-MIDI
CD-MIDI is a format used to store music-performance data, which upon playback is performed by electronic instruments that synthesize the audio. Hence, unlike the original Red Book CD-DA, these recordings are not digitally sampled audio recordings. The CD-MIDI format is defined as an extension of the original Red Book.

CD-ROM
For the first few years of its existence, the CD was a medium used purely for audio. In 1988, the Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data computer data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive.

Video CD
Video CD (VCD, View CD, and Compact Disc digital video) is a standard digital format for storing video media on a CD. VCDs are playable in dedicated VCD players, most modern DVD-Video players, personal computers, and some video game consoles. The VCD standard was created in 1993 by Sony, Philips, Matsushita, and JVC and is referred to as the White Book standard.

Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be of lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise and does not deteriorate further with each use. 352×240 (or SIF) resolution was chosen because it is half the vertical and half the horizontal resolution of the NTSC video. 352×288 is a similarly one-quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution.

Super Video CD
Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video media on standard compact discs. SVCD was intended as a successor to VCD and an alternative to DVD-Video and falls somewhere between both in terms of technical capability and picture quality.

SVCD has two-thirds the resolution of DVD, and over 2.7 times the resolution of VCD. One CD-R disc can hold up to 60 minutes of standard-quality SVCD-format video. While no specific limit on SVCD video length is mandated by the specification, one must lower the video bit rate, and therefore quality, to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring a significant quality loss, and many hardware players are unable to play a video with an instantaneous bit rate lower than 300 to 600 kilobits per second.

Photo CD
Photo CD is a system designed by Kodak for digitizing and storing photos on a CD. Launched in 1992, the discs were designed to hold nearly 100 high-quality images, scanned prints, and slides using special proprietary encoding. Photo CDs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well. They are intended to play on CD-i players, Photo CD players, and any computer with suitable software (irrespective of operating system). The images can also be printed out on photographic paper with a special Kodak machine. This format is not to be confused with Kodak Picture CD, which is a consumer product in CD-ROM format.

CD-i
The Philips Green Book specifies a standard for interactive multimedia compact discs designed for CD-i players (1993). CD-i discs can contain audio tracks that can be played on regular CD players, but CD-i discs are not compatible with most CD-ROM drives and software. The CD-i Ready specification was later created to improve compatibility with audio CD players, and the CD-i Bridge specification was added to create CD-i-compatible discs that can be accessed by regular CD-ROM drives.

CD-i Ready
Philips defined a format similar to CD-i called CD-i Ready, which puts CD-i software and data into the pregap of track 1. This format was supposed to be more compatible with older audio CD players.

Enhanced Music CD (CD+)
Enhanced Music CD, also known as CD Extra or CD Plus, is a format that combines audio tracks and data tracks on the same disc by putting audio tracks in a first session and data in a second session. It was developed by Philips and Sony, and it is defined in the Blue Book.

VinylDisc
VinylDisc is the hybrid of a standard audio CD and the vinyl record. The vinyl layer on the disc's label side can hold approximately three minutes of music.

Manufacture, cost, and pricing

In 1995, material costs were 30 cents for the jewel case and 10 to 15 cents for the CD. The wholesale cost of CDs was $0.75 to $1.15, while the typical retail price of a prerecorded music CD was $16.98. On average, the store received 35 percent of the retail price, the record company 27 percent, the artist 16 percent, the manufacturer 13 percent, and the distributor 9 percent. When 8-track cartridges, compact cassettes, and CDs were introduced, each was marketed at a higher price than the format they succeeded, even though the cost to produce the media was reduced. This was done because the perceived value increased. This continued from phonograph records to CDs, but was broken when Apple marketed MP3s for $0.99, and albums for $9.99. The incremental cost, though, to produce an MP3 is negligible.

Recordable CD

Recordable Compact Discs, CD-Rs, are injection-molded with a "blank" data spiral. A photosensitive dye is then applied, after which the discs are metalized and lacquer-coated. The write laser of the CD recorder changes the color of the dye to allow the read laser of a standard CD player to see the data, just as it would with a standard stamped disc. The resulting discs can be read by most CD-ROM drives and played in most audio CD players. CD-Rs follow the Orange Book standard.

CD-R recordings are designed to be permanent. Over time, the dye's physical characteristics may change causing read errors and data loss until the reading device cannot recover with error correction methods. Errors can be predicted using surface error scanning. The design life is from 20 to 100 years, depending on the quality of the discs, the quality of the writing drive, and storage conditions. Testing has demonstrated such degradation of some discs in as little as 18 months under normal storage conditions. This failure is known as disc rot, for which there are several, mostly environmental, reasons.

The recordable audio CD is designed to be used in a consumer audio CD recorder. These consumer audio CD recorders use SCMS (Serial Copy Management System), an early form of digital rights management (DRM), to conform to the AHRA (Audio Home Recording Act). The Recordable Audio CD is typically somewhat more expensive than CD-R due to lower production volume and a 3 percent AHRA royalty used to compensate the music industry for the making of a copy.

High-capacity recordable CD is a higher-density recording format that can hold 20% more data than conventional discs. The higher capacity is incompatible with some recorders and recording software.

ReWritable CD
CD-RW is a re-recordable medium that uses a metallic alloy instead of a dye. The write laser, in this case, is used to heat and alter the properties (amorphous vs. crystalline) of the alloy, and hence change its reflectivity. A CD-RW does not have as great a difference in reflectivity as a pressed CD or a CD-R, and so many earlier CD audio players cannot read CD-RW discs, although most later CD audio players and stand-alone DVD players can. CD-RWs follow the Orange Book standard.

The ReWritable Audio CD is designed to be used in a consumer audio CD recorder, which will not (without modification) accept standard CD-RW discs. These consumer audio CD recorders use the Serial Copy Management System (SCMS), an early form of digital rights management (DRM), to conform to the United States' Audio Home Recording Act (AHRA). The ReWritable Audio CD is typically somewhat more expensive than CD-R due to (a) lower volume and (b) a 3 percent AHRA royalty used to compensate the music industry for the making of a copy.

Copy protection
The Red Book audio specification, except for a simple "anti-copy" statement in the subcode, does not include any copy protection mechanism. Known at least as early as 2001, attempts were made by record companies to market "copy-protected" non-standard compact discs, which cannot be ripped, or copied, to hard drives or easily converted to other formats (like FLAC, MP3 or Vorbis). One major drawback to these copy-protected discs is that most will not play on either computer CD-ROM drives or some standalone CD players that use CD-ROM mechanisms. Philips has stated that such discs are not permitted to bear the trademarked Compact Disc Digital Audio logo because they violate the Red Book specifications. Numerous copy-protection systems have been countered by readily available, often free, software, or even by simply turning off automatic AutoPlay to prevent the running of the DRM executable program.

title: Compact disc


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Charles Farrar Browne

Charles Farrar Browne (April 26, 1834 – March 6, 1867) was an American humor writer, better known under his nom de plume, Artemus Ward, which as a character, an illiterate rube with "Yankee common sense", Browne also played in public performances. He is considered to be America's first stand-up comedian. His birth name was Brown but he added the "e" after he became famous.

Biography
Browne was born in Waterford, Maine. He began his career as a compositor and occasional contributor to the daily and weekly journals. In 1858, in The Plain Dealer newspaper (Cleveland, Ohio), he published the first of the "Artemus Ward" series, which, in collected form, achieved great popularity in both America and England.

Browne's companion at the Plain Dealer, George Hoyt, wrote: "his desk was a rickety table which had been whittled and gashed until it looked as if it had been the victim of lightning. His chair was a fit companion thereto, a wabbling, unsteady affair, sometimes with four and sometimes with three legs. But Browne saw neither the table, nor the chair, nor any person who might be near, nothing, in fact, but the funny pictures which were tumbling out of his brain. When writing, his gaunt form looked ridiculous enough. One leg hung over the arm of his chair like a great hook, while he would write away, sometimes laughing to himself, and then slapping the table in the excess of his mirth." In 1860, he became editor of the first Vanity Fair, a humorous New York weekly that failed in 1863. At about the same time, he began to appear as a lecturer who, by his droll and eccentric humor, attracted large audiences. Browne was also known as a member of the New York bohemian set which included leader Henry Clapp Jr., Walt Whitman, Fitz Hugh Ludlow, and actress Adah Isaacs Menken.

In 1863, Browne came to San Francisco to perform as Artemus Ward. An early expert at show business publicity, Browne sent his manager ahead by several weeks to buy advertising in the local papers and promote the show among prominent citizens for endorsements. On November 13, 1863, Browne stood before a packed crowd at Platt's Music Hall, playing the part of Artemus Ward as an illiterate rube but with "Yankee common sense." Writer Bret Harte was in the audience that night and he described it in the Golden Era as capturing American speech: "humor that belongs to the country of boundless prairies, limitless rivers, and stupendous cataracts—that fun which overlies the surface of our national life, which is met in the stage, rail-car, canal and flat-boat, which bursts out over camp-fires and around bar-room stoves."

"Artemus Ward" was a favorite author of U.S. President Abraham Lincoln. Before presenting "The Emancipation Proclamation" to his Cabinet, Lincoln read to them the latest episode, "Outrage in Utiky", also known as "High-Handed Outrage at Utica".

When Browne performed in Virginia City, Nevada, he met Mark Twain and the two became friends. In his correspondence with Twain, Browne called him "My Dearest Love." Legend has it that, following a stage performance there, Browne, Twain, and Dan De Quille were trekking on a (drunken) rooftop tour of Virginia City until a town constable threatened to blast all three with a shotgun loaded with rock salt. Browne recommended Twain to the editors of the New York Press and urged him to journey to New York.

In 1866, Browne visited England and attracted a large following to his playing Artemus Ward, both as lecturer and for his literary contributions to Punch. But within a year his health gave way and he died of tuberculosis at Southampton on March 6, 1867.

In England Browne was buried at Kensal Green Cemetery, but his remains were removed to the United States in 1868 and buried at Elm Vale Cemetery in Waterford, Maine.

Legacy
In Cleveland, where Browne started his comedy career, an elementary school is named after him, known as Artemus Ward Elementary on W. 140th Street. In the American Garden of the Cleveland Cultural Gardens in Rockefeller Park, a monument of him was erected, next to Mark Twain.

Stories

 * A Visit to Brigham Young
 * Women's Rights
 * One of Mr Ward's Business Letters
 * On "Forts"
 * Fourth of July Oration
 * High-Handed Outrage at Utica
 * Artemus Ward and the Prince of Wales
 * Interview with Lincoln
 * Letters to his Wife

Books

 * Artemus Ward His Book (1862) (full text online)
 * Artemus Ward His Travels (1865) (full text online)
 * Artemus Ward Among the Mormons (1865) (full text online)
 * Artemus Ward in London (1867) (full text online)
 * Artemus Ward's Panorama (1869) (full text online)
 * Artemus Ward's Lecture (1869) (full text online)

title: Charles Farrar Browne


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Caelum

Caelum is a faint constellation in the southern sky, introduced in the 1750s by Nicolas Louis de Lacaille and counted among the 88 modern constellations. Its name means "chisel" in Latin, and it was formerly known as Caelum Sculptorium ("Engraver's Chisel"); it is a rare word, unrelated to the far more common Latin caelum, meaning "sky", "heaven", or "atmosphere". It is the eighth-smallest constellation, and subtends a solid angle of around 0.038 steradians, just less than that of Corona Australis.

Due to its small size and location away from the plane of the Milky Way, Caelum is a rather barren constellation, with few objects of interest. The constellation's brightest star, Alpha Caeli, is only of magnitude 4.45, and only one other star, (Gamma) γ1 Caeli, is brighter than magnitude 5undefined. Other notable objects in Caelum are RR Caeli, a binary star with one known planet approximately 20.13 pc away; X Caeli, a Delta Scuti variable that forms an optical double with γ1 Caeli; and HE0450-2958, a Seyfert galaxy that at first appeared as just a jet, with no host galaxy visible.

History
Caelum was incepted as one of fourteen southern constellations in the 18th century by Nicolas Louis de Lacaille, a French astronomer and celebrated of the Age of Enlightenment. It retains its name Burin among French speakers, latinized in his catalogue of 1763 as Caelum Sculptoris (“Engraver's Chisel”). Francis Baily shortened this name to Caelum, as suggested by John Herschel. In Lacaille's original chart, it was shown as a pair of engraver's tools: a standard burin and more specific shape-forming échoppe tied by a ribbon, but came to be ascribed a simple chisel. Johann Elert Bode stated the name as plural with a singular possessor, Caela Scalptoris – in German (dieundefined) Grabstichel (“the Engraver’s Chisels”) – but this did not stick.

Characteristics
Caelum is bordered by Dorado and Pictor to the south, Horologium and Eridanus to the east, Lepus to the north, and Columba to the west. Covering only 125 square degrees, it ranks 81st of the 88 modern constellations in size.

Its main asterism consists of four stars, and twenty stars in total are brighter than magnitude 6.5undefined.

The constellation's boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are a 12-sided polygon. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04:19.5:0 and 05:05.1:0 and declinations of −27.02° to −48.74°. The International Astronomical Union (IAU) adopted the three-letter abbreviation “Cae” for the constellation in 1922.

Its main stars are visible in favourable conditions and with a clear southern horizon, for part of the year as far as about the 41st parallel north

These stars avoid being engulfed by daylight for some of every day (when above the horizon) to viewers in mid- and well-inhabited higher latitudes of the Southern Hemisphere. Caelum shares with (to the north) Taurus, Eridanus and Orion midnight culmination in December (high summer), resulting in this fact. In winter (such as June) the constellation can be observed sufficiently inset from the horizons during its rising before dawn and/or setting after dusk as it culminates then at around mid-day, well above the sun. In South Africa, Argentina, their sub-tropical neighbouring areas and some of Australia in high June the key stars may be traced before dawn in the east; near the equator the stars lose night potential in May to June; they ill-compete with the Sun in northern tropics and sub-tropics from late February to mid-September with March being unfavorable as to post-sunset due to the light of the Milky Way.

Stars
Caelum is a faint constellation: It has no star brighter than magnitude 4 and only two stars brighter than magnitude 5.

Lacaille gave six stars Bayer designations, labeling them Alpha (αundefined) to Zeta (ζundefined) in 1756, but omitted Epsilon (εundefined) and designated two adjacent stars as Gamma (γundefined). Bode extended the designations to Rho (ρundefined) for other stars, but most of these have fallen out of use. Caelum is too far south for any of its stars to bear Flamsteed designations.

The brightest star, (Alpha) α Caeli, is a double star, containing an F-type main-sequence star of magnitude 4.45 and a red dwarf of magnitude 12.5undefined, 20.17 pc from Earth. (Beta) β Caeli, another F-type star of magnitude 5.05undefined, is further away, being located 28.67 pc from Earth. Unlike α, β Caeli is a subgiant star, slightly evolved from the main sequence. (Delta) δ Caeli, also of magnitude 5.05undefined, is a B-type subgiant and is much farther from Earth, at 216 pc.

(Gamma) γ1Caeli is a double-star with a red giant primary of magnitude 4.58 and a secondary of magnitude 8.1undefined. The primary is 55.59 pc from Earth. The two components are difficult to resolve with small amateur telescopes because of their difference in visual magnitude and their close separation. This star system forms an optical double with the unrelated X Caeli (previously named γ2Caeli), a Delta Scuti variable located 98.33 pc from Earth. These are a class of short-period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology. X Caeli itself is also a binary star, specifically a contact binary, meaning that the stars are so close that they share envelopes. The only other variable star in Caelum visible to the naked eye is RV Caeli, a pulsating red giant of spectral type M1III, which varies between magnitudes 6.44 and 6.56undefined.

Three other stars in Caelum are still occasionally referred to by their Bayer designations, although they are only on the edge of naked-eye visibility. (Nu) ν Caeli is another double star, containing a white giant of magnitude 6.07 and a star of magnitude 10.66, with unknown spectral type. The system is approximately 52.55 pc away. (Lambda) λ Caeli, at magnitude 6.24, is much redder and farther away, being a red giant around 227 pc from Earth. (Zeta) ζ Caeli is even fainter, being only of magnitude 6.36undefined. This star, located 132 pc away, is a K-type subgiant of spectral type K1. The other twelve naked-eye stars in Caelum are not referred to by Bode's Bayer designations anymore, including RV Caeli.

One of the nearest stars in Caelum is the eclipsing binary star RR Caeli, at a distance of 20.13 pc. This star system consists of a dim red dwarf and a white dwarf. Despite its closeness to the Earth, the system's apparent magnitude is only 14.40 due to the faintness of its components, and thus it cannot be easily seen with amateur equipment. The system is a post-common-envelope binary and is losing angular momentum over time, which will eventually cause mass transfer from the red dwarf to the white dwarf. In approximately 9–20 billion years, this will cause the system to become a cataclysmic variable.

LHS 1678 is an astrometric binary located some 65 light-years away. The primary star is a red dwarf hosting three close-in exoplanets, all smaller than Earth. The other component is a likely brown dwarf. It is the closest neighbout to Alpha Caeli, just 3.3 light-years distant from it. Due to its closeness, α Caeli would shine at magnitude $-2.01$ from LHS 1678, brighter than Sirius in our sky.

Deep-sky objects
Due to its small size and location away from the plane of the Milky Way, Caelum is rather devoid of deep-sky objects, and contains no Messier objects. The only deep-sky object in Caelum to receive much attention is HE0450-2958, an unusual Seyfert galaxy. Originally, the jet's host galaxy proved elusive to find, and this jet appeared to be emanating from nothing. Although it has been suggested that the object is an ejected supermassive black hole, the host is now agreed to be a small galaxy that is difficult to see due to light from the jet and a nearby starburst galaxy.

The 13th magnitude planetary nebula PN G243-37.1 is also in the eastern regions of the constellation. It is one of only a few planetary nebulae found in the galactic halo, being $-3.03$ light-years below the Milky Way's 1000 light-year-thick disk.

Galaxies NGC 1595, NGC 1598, and the Carafe galaxy are known as the Carafe group. The Carafe galaxy is a Seyfert galaxy with ring. Its location is 4:28 / -47°54' (2000.0).

title: Caelum