Orbit is also a word for an eye socket.

An orbit is the path that an object takes in space when it goes around a star, a planet, or a moon. It can also be used as a verb. For instance: "The earth orbits around the Sun." The word 'revolves' has the same meaning, but 'rotates' is the spin of the object.

Many years ago, people thought that the Sun orbits in a circle around the Earth. Every morning the Sun came up in the East and went down in the West. It just seemed to make sense that it was going around the Earth. But now, thanks to people like Copernicus and Galileo Galilei, we know that the Sun is the center of the Solar System, and the Earth orbits around it.  Isaac Newton discovered that gravity controls the orbit of the planets and moons.  Since a satellite is an object in space that revolves around another object, the Earth is a satellite of the Sun, just like the moon is a satellite of the Earth. The Sun has lots of satellites orbiting around it, like the planets, and asteroids, comets, and meteoroids. The Earth just has one natural satellite (the Moon), but there are many artificial satellites orbiting the earth.

When people first began to think about orbits, they thought that all orbits had to be perfect circles, and they thought that the circle was a "perfect" shape. Copernicus and Galileo, for example, thought so. But when people began to study the motions of planets carefully, they saw that the planets were not moving in perfect circles.

In a planetary system, planets, dwarf planets, asteroids and other minor planets, comets, and space debris orbit the system's barycenter in elliptical orbits.

Orbital period
An orbital period is the time that it takes for one object - that is, satellite - to orbit around another object. For instance, the Earth's orbital period is one year: 365.25 days. (The extra ".25" is why we have a leap day once every four years).

The Moon takes 27 days (29.53 days as seen from Earth) to go around the Earth and also to rotate around its own axis. This is why only one side always faces the Earth and the "dark side of the Moon" faces away (it is called dark because we cannot see it, though all sides of the moon get light). One lunar year and one lunar day take the same amount of time.

Elliptical and eccentric orbits
Johannes Kepler (lived 15711630) wrote mathematical "laws of planetary motion", which gave a good idea of the movements of the planets because he found that the orbits of the planets in our Solar System are not really circles, but are really ellipses (a shape like a "flattened circle"). That is why orbits are described as elliptical.

The more elliptical an orbit is, the more eccentric the orbit is. This is called orbital eccentricity. Other numbers that describe an elliptical orbit include semi-major axis and orbital inclination.

Isaac Newton (lived 1642–1727) used his own ideas about gravity to show why Kepler's laws worked the way they did. Joseph-Louis Lagrange further advanced the study of orbital mechanics, using Newton's theory to predict perturbations which change the shapes of orbits.

References

Orbit


The Eisriesenwelt (German for "World of the Ice Giants") is a natural limestone and ice cave located in Werfen, Austria, about 40 km south of Salzburg.  The cave is inside the Hochkogel mountain in the Tennengebirge section of the Alps.  It is the largest ice cave in the world, extending more than 42 km and visited by about 200,000 tourists every year.

Geology

The Tennengebirge mountains were formed during the late Tertiary period, during the Würm glaciation period of the Pleistocene. The mountain range, one of the massifs in the Austrian Alps, is the largest karst plateau in the Salzburger Alps, and the Eisriesenwelt is located at the rim of this plateau. Although the cave has a length of 42 km, only the first kilometer, the area that tourists are allowed to visit, is covered in ice. The rest of the cave is formed of limestone.

Eisriesenwelt was formed by the Salzach river, which eroded passageways into the mountain.  The ice formations in the cave were formed by thawing snow which drained into the cave and froze during winter.

Since the entrance to the caves is open year-round, chilly winter winds blow into the cave and freeze the snow inside. In summer, a cold wind from inside the cave blows toward the entrance and prevents the formations from melting.

History
The first official discovery of Eisriesenwelt was by Anton Posselt, a natural scientist from Salzburg, in 1879, though he only explored the first two hundred meters of the cave. Before his discovery, the cave was known only to locals, who, believing that it was an entrance to Hell, refused to explore it. In 1880, Posselt published his findings in a mountaineering magazine, but the report was quickly forgotten.

, a speleologist from Salzburg, was one of the few people who remembered Posselt's discovery. He led several expeditions into the caves beginning in 1912, which were soon followed by other explorers. Von Mörk was killed in World War I in 1914, and an urn containing his ashes is inside a niche in the cave. In 1920, a cabin for the explorers, Forscherhütte, was built and the first routes up the mountain were established. Tourists began to arrive soon after, attracted by the cave's sudden popularity. Later another cabin, the Dr. Oedl House, and paths from Werfen and Tenneck were constructed.

In 1955 a cable car was built, shortening the 90-minute climb to 3 minutes. Today the Eisriesenwelt cave is owned by the , which has leased it to the Salzburg Association of Cave Exploration since 1928. The Forest Commission still receives a percentage of the entrance fees.

Visiting

The cave is open from May 1 to October 26 every year.  Its operating hours are 9:00 a.m. to 4:30 p.m. in July and August and 9:00 a.m. to 3:30 p.m. in May/June and September/October.  Temperatures inside the cave are usually below freezing, and warm clothing is recommended. Photography is not permitted once visitors are inside the cave.

The tour begins at the entrance to the cave, and continues inwards to Posselt Hall, a large room with a stalagmite called Posselt Tower in the centre. Past the Posselt Tower, one encounters an ashen cross on the wall of the cave, marking the farthest point of exploration of Anton Posselt. From there one can see the Great Ice Embankment, a massive formation that rises to a height of 25 metres and represents the area of greatest ice growth. Next is Hymir's Castle, named after a giant in Norse mythology. Here stalactites create a formation called Frigga's Veil, or the Ice Organ.

Next on the tour is the Alexander von Mörk Cathedral, one of the largest rooms in the cave and the final resting place of von Mörk's ashes. The final stop on the tour is the Ice Palace, a kilometre into the cave and 400 metres underground. From here, visitors must turn around and walk back through the caves to reach the entrance.  The round-trip tour through the cave takes around one hour and 15 minutes.

Gallery

References

External links

 Travel guide
 Cave information
 Tourist's description of visiting the cave
 Description of Tennengebirge geology

Limestone caves
Caves of Austria
Ice caves
Show caves in Austria
Landforms of Salzburg (state)
Tourist attractions in Salzburg (state)

Eisriesenwelt


The Reading and Leeds Festivals are two yearly music festivals. They take place in Reading and Leeds in the United Kingdom. They are run by Festival Republic (itself owned by Live Nation and MCD). The festivals take place one at a time on the Friday, Saturday and Sunday. They take place on the August of bank holiday weekend. They share the same bill. Between 1998 and 2007, the two festivals were known as the "Carling Weekend", until parting ways with their sponsor Carling in November 2007.

Other websites

Music festivals in England

Reading and Leeds Festivals


(Latin: ) was a hypothetical continent first posited in antiquity and which appeared on maps between the 15th and 18th centuries. Its existence was not based on any survey or direct observation, but rather on the idea that continental land in the Northern Hemisphere should be balanced by land in the Southern Hemisphere. This theory of balancing land has been documented as early as the 5th century on maps by Macrobius, who uses the term  on his maps.

Names
Other names for the hypothetical continent have included Terra Australis Ignota, Terra Australis Incognita ("the unknown land of the south") or Terra Australis Nondum Cognita ("the southern land not yet known"). Other names were Brasiliae Australis ("the southern Brazil"), and Magellanica ("the land of Magellan"). Matthias Ringmann called it the Ora antarctica (antarctic land) in 1505, and Franciscus Monachus called it the Australis orę (Austral country). In Medieval times it was known as the Antipodes.

Change of name
During the eighteenth century, today's Australia was not conflated with Terra Australis, as it sometimes was in the twentieth century. Captain Cook and his contemporaries knew that the sixth continent (today's Australia), which they called New Holland, was entirely separate from the imagined (but still undiscovered) seventh continent (today's Antarctica).

In the nineteenth century, the colonial authorities in Sydney re-allocated the name Australia to New Holland and its centuries-old Dutch name eventually disappeared. Meanwhile, having lost its name of Australia, the south polar continent was nameless for decades  until Antarctica was coined in the 1890s.

In the early 1800s, British explorer Matthew Flinders popularized the naming of Australia after Terra Australis, giving his rationale that there was "no probability" of finding any significant land mass anywhere more south than Australia.  The continent that would come to be named Antarctica would be explored decades after Flinders' 1814 book on Australia, which he had titled A Voyage to Terra Australis, and after his naming switch had gained popularity.

History

Origins

Ptolemy (2nd century AD) believed that the Indian Ocean was enclosed on the south by land, and that the lands of the Northern Hemisphere should be balanced by land in the south. Marcus Tullius Cicero used the term cingulus australis ("southern zone") in referring to the Antipodes in Somnium Scipionis ("Dream of Scipio"). The land (terra in Latin) in this zone was the Terra Australis.

Legends of Terra Australis Incognitaan "unknown land of the South"date back to Roman times and before, and were commonplace in medieval geography, although not based on any documented knowledge of the continent. Ptolemy's maps, which became well known in Europe during the Renaissance, did not actually depict such a continent, but they did show an Africa which had no southern oceanic boundary (and which therefore might extend all the way to the South Pole), and also raised the possibility that the Indian Ocean was entirely enclosed by land. Christian thinkers did not discount the idea that there might be land beyond the southern seas, but the issue of whether it could be inhabited was controversial.

The first depiction of Terra Australis on a globe was probably on Johannes Schöner's lost 1523 globe on which Oronce Fine is thought to have based his 1531 double cordiform (heart-shaped) map of the world. On this landmass he wrote "recently discovered but not yet completely explored". The body of water beyond the tip of South America is called the "Mare Magellanicum", one of the first uses of navigator Ferdinand Magellan's name in such a context.

Schöner called the continent Brasiliae Australis in his 1533 tract, Opusculum geographicum. In it, he explained: Brasilia Australis is an immense region toward Antarcticum, newly discovered but not yet fully surveyed, which extends as far as Melacha and somewhat beyond. The inhabitants of this region lead good, honest lives and are not Anthropophagi [cannibals] like other barbarian nations; they have no letters, nor do they have kings, but they venerate their elders and offer them obedience; they give the name Thomas to their children [after St Thomas the Apostle]; close to this region lies the great island of Zanzibar at 102.00 degrees and 27.30 degrees South.

Mapping the southern continent

Medieval period

During medieval times Terra Australis was known by a different name, that being the Antipodes. First widely introduced to medieval western Europe by Isidore of Seville in his famous book the Etymologiae, the idea gained popularity across Europe, and most scholars did not question its existence, instead debating if it was habitable for other humans. It would later be included on some zonal Mappa mundi and intrigue medieval scholars for centuries.

16th century

Explorers of the Age of Discovery, from the late 15th century on, proved that Africa was almost entirely surrounded by sea, and that the Indian Ocean was accessible from both west and east.  These discoveries reduced the area where the continent could be found; however, many cartographers held to Aristotle's opinion. Scientists such as Gerardus Mercator (1569) and Alexander Dalrymple as late as 1767 argued for its existence, with such arguments as that there should be a large landmass in the south as a counterweight to the known landmasses in the Northern Hemisphere. As new lands were discovered, they were often assumed to be parts of the hypothetical continent.

The German cosmographer and mathematician Johannes Schöner (1477–1547) constructed a terrestrial globe in 1515, based on the world map and globe made by Martin Waldseemüller and his colleagues at St. Dié in Lorraine in 1507. Where Schöner departs most conspicuously from Waldseemüller is in his globe's depiction of an Antarctic continent, called by him Brasilie Regio. His continent is based, however tenuously, on the report of an actual voyage: that of the Portuguese merchants Nuno Manuel and Cristóvão de Haro to the River Plate, and related in the Newe Zeytung auss Presillg Landt ("New Tidings from the Land of Brazil") published in Augsburg in 1514. The Zeytung described the Portuguese voyagers passing through a strait between the southernmost point of America, or Brazil, and a land to the south west, referred to as vndtere Presill (or Brasilia inferior).

This supposed "strait" was in fact the Rio de la Plata (or the San Matias Gulf). By "vndtere Presill", the Zeytung meant that part of Brazil in the lower latitudes, but Schöner mistook it to mean the land on the southern side of the "strait", in higher latitudes, and so gave to it the opposite meaning. On this slender foundation he constructed his circum-Antarctic continent to which, for the reasons that he does not explain, he gave an annular, or ring shape. In an accompanying explanatory treatise, Luculentissima quaedam terrae totius descriptio ("A Most Lucid Description of All Lands"), he explained:The Portuguese, thus, sailed around this region, the Brasilie Regio, and discovered the passage very similar to that of our Europe (where we reside) and situated laterally between east and west. From one side the land on the other is visible; and the cape of this region about  away, much as if one were sailing eastward through the Straits of Gibraltar or Seville and Barbary or Morocco in Africa, as our Globe shows toward the Antarctic Pole. Further, the distance is only moderate from this Region of Brazil to Malacca, where St. Thomas was crowned with martyrdom.

On this scrap of information, united with the concept of the Antipodes inherited from Graeco-Roman antiquity, Schöner constructed his representation of the southern continent. His strait served as inspiration for Ferdinand Magellan's expedition to reach the Moluccas by a westward route.

He took Magellan's discovery of Tierra del Fuego in 1520 as further confirmation of its existence, and on his globes of 1523 and 1533 he described it as terra australis recenter inventa sed nondum plene cognita ("Terra Australis, recently discovered but not yet fully known"). It was taken up by his followers, the French cosmographer Oronce Fine in his world map of 1531, and the Flemish cartographers Gerardus Mercator in 1538 and Abraham Ortelius in 1570. Schöner's concepts influenced the Dieppe school of mapmakers, notably in their representation of Jave la Grande.

In 1539, the King of Spain, Charles V, created the Governorate of Terra Australis  granted to Pedro Sancho de la Hoz, who in 1540 transferred the title to the conqueror Pedro de Valdivia and later was incorporated to Chile.

Terra Australis was depicted on the mid-16th-century Dieppe maps, where its coastline appeared just south of the islands of the East Indies; it was often elaborately charted, with a wealth of fictitious detail. There was much interest in Terra Australis among Norman and Breton merchants at that time. In 1566 and 1570, Francisque and André d'Albaigne presented Gaspard de Coligny, Admiral of France, with projects for establishing relations with the Austral lands. Although the Admiral gave favourable consideration to these initiatives, they came to nought when Coligny was killed in 1572.

Gerardus Mercator believed in the existence of a large Southern continent on the basis of cosmographic reasoning, set out in the abstract of his Atlas or Cosmographic Studies in Five Books, as related by his biographer, Walter Ghim, who said that even though Mercator was not ignorant that the Austral continent still lay hidden and unknown, he believed it could be "demonstrated and proved by solid reasons and arguments to yield in its geometric proportions, size and weight, and importance to neither of the other two, nor possibly to be lesser or smaller, otherwise the constitution of the world could not hold together at its centre".

The Flemish geographer and cartographer, Cornelius Wytfliet, wrote concerning the Terra Australis in his 1597 book, Descriptionis Ptolemaicae Augmentum:
The terra Australis is therefore the southernmost of all other lands, directly beneath the antarctic circle; extending beyond the tropic of Capricorn to the West, it ends almost at the equator itself, and separated by a narrow strait lies on the East opposite to New Guinea, only known so far by a few shores because after one voyage and another that route has been given up and unless sailors are forced and driven by stress of winds it is seldom visited. The terra Australis begins at two or three degrees below the equator and it is said by some to be of such magnitude that if at any time it is fully discovered they think it will be the fifth part of the world.

Adjoining Guinea on the right are the numerous and vast Solomon Islands which lately became famous by the voyage of Alvarus Mendanius.

Juan Fernandez, sailing from Chile in 1576, claimed he had discovered the Southern Continent. The Polus Antarcticus map of 1641 by Henricus Hondius, bears the inscription: "Insulas esse a Nova Guinea usque ad Fretum Magellanicum affirmat Hernandus Galego, qui ad eas explorandas missus fuit a Rege Hispaniae Anno 1576 (Hernando Gallego, who in the year 1576 was sent by the King of Spain to explore them, affirms that there are islands from New Guinea up to the Strait of Magellan)".

17th century
Luís Vaz de Torres, a Spanish navigator who commanded the San Pedro y San Pablo, the San Pedrico and the tender or yacht, Los Tres Reyes Magos during the 1605–1606 expedition led by Pedro Fernandes de Queiros in quest of the Southern Continent, proved the existence of a passage south of New Guinea, now known as Torres Strait. Commenting on this in 1622, the Dutch cartographer and publisher of Queiros' eighth memorial, Hessel Gerritsz, noted on his Map of the Pacific Ocean: "Those who sailed with the yacht of Pedro Fernando de Quiros in the neighbourhood of New Guinea to 10 degrees westward through many islands and shoals and over  for as many as 40 days, estimated that Nova Guinea does not extend beyond 10 degrees to the south; if this be so, then the land from 9 to 14 degrees would be a separate land".

Pedro Fernandes de Queirós, another Portuguese navigator sailing for the Spanish Crown, saw a large island south of New Guinea in 1606, which he named La Austrialia del Espiritu Santo. He represented this to the King of Spain as the Terra Australis incognita. In his 10th Memorial (1610), Queirós said: "New Guinea is the top end of the Austral Land of which I treat [discuss], and that people, and customs, with all the rest referred to, resemble them".

Dutch father and son Isaac and Jacob Le Maire established the Australische Compagnie (Australian Company) in 1615 to trade with Terra Australis, which they called "Australia".

The Dutch expedition to Valdivia of 1643 intended to round Cape Horn sailing through Le Maire Strait but strong winds made it instead drift south and east. The small fleet led by Hendrik Brouwer managed to enter the Pacific ocean sailing south of the island disproving earlier beliefs that it was part of Terra Australis.

The cartographic depictions of the southern continent in the 16th and early 17th centuries, as might be expected for a concept based on such abundant conjecture and minimal data, varied wildly from map to map; in general, the continent shrank as potential locations were reinterpreted.  At its largest, the continent included Tierra del Fuego, separated from South America by a small strait; New Guinea; and what would come to be called Australia.  In Ortelius's atlas Theatrum Orbis Terrarum, published in 1570, Terra Australis extends north of the Tropic of Capricorn in the Pacific Ocean.

As long as it appeared on maps at all, the continent minimally included the unexplored lands around the South Pole, but generally much larger than the real Antarctica, spreading far north – especially in the Pacific Ocean. New Zealand, first seen by the Dutch explorer Abel Tasman in 1642, was regarded by some as a part of the continent.

18th century
Alexander Dalrymple, the Examiner of Sea Journals for the English East India Company, whilst translating some Spanish documents captured in the Philippines in 1762, found de Torres's testimony.  This discovery led Dalrymple to publish the Historical Collection of the Several Voyages and Discoveries in the South Pacific Ocean in 1770–1771. Dalrymple presented a beguiling tableau of the Terra Australis, or Southern Continent:
The number of inhabitants in the Southern Continent is probably more than 50 millions, considering the extent, from the eastern part discovered by Juan Fernandez, to the western coast seen by Tasman, is about 100 deg. of longitude, which in the latitude of 40 deg. amounts to 4596 geographic, or 5323 stature miles [8567 km]. This is a greater extent than the whole civilized part of Asia, from Turkey to the eastern extremity of China. There is at present no trade from Europe thither, though the scraps from this table would be sufficient to maintain the power, dominion, and sovereignty of Britain, by employing all its manufacturers and ships. Whoever considers the Peruvian empire, where arts and industry flourished under one of the wisest systems of government, which was founded by a stranger, must have very sanguine expectations of the southern continent, from whence it is more than probable Mango Capac, the first Inca, was derived, and must be convinced that the country, from whence Mango Capac introduced the comforts of civilized life, cannot fail of amply rewarding the fortunate people who shall bestow letters instead of quippos (quipus), and iron in place of more awkward substitutes.
Dalrymple's claim of the existence of an unknown continent aroused widespread interest and prompted the British government in 1769 to order James Cook in HM Bark Endeavour to seek out the Southern Continent to the South and West of Tahiti, discovered in June 1767 by Samuel Wallis in  and named by him King George Island. The London press reported in June 1768 that two ships would be sent to the newly discovered island and from there to "attempt the Discovery of the Southern Continent". A subsequent press report stated: "We are informed, that the Island which Captain Wallis has discovered in the South-Sea, and named George's Land, is about fifteen hundred Leagues to the Westward and to Leeward of the Coast of Peru, and about five-and-thirty Leagues in circumference; that its principal and almost sole national Advantage is, its Situation for exploring the Terra Incognita of the Southern Hemisphere. The Endeavour, a North-Country Cat, is purchased by the Government, and commanded by a Lieutenant of the Navy; she is fitting out at Deptford for the South-Sea, thought to be intended for the newly-discovered Island". The aims of the expedition were revealed in days following: "To-morrow morning Mr. Banks, Dr. Solano [sic], with Mr. Green, the Astronomer, will set out for Deal, to embark on board the Endeavour, Capt. Cook, for the South Seas, under the direction of the Royal Society, to observe the Transit of Venus next summer, and to make discoveries to the South and West of Cape Horn". The London Gazetteer was more explicit when it reported on 18 August 1768: "The gentlemen, who are to sail in a few days for George's Land, the new discovered island in the Pacific ocean, with an intention to observe the Transit of Venus, are likewise, we are credibly informed, to attempt some new discoveries in that vast unknown tract, above the latitude 40". The results of this first voyage of James Cook in respect of the quest for the Southern Continent were summed up by Cook himself. He wrote in his Journal on 31 March 1770 that the Endeavour voyage "must be allowed to have set aside the most, if not all, the Arguments and proofs that have been advanced by different Authors to prove that there must be a Southern Continent; I mean to the Northward of 40 degrees South, for what may lie to the Southward of that Latitude I know not".

The second voyage of James Cook aboard  explored the South Pacific for the landmass between 1772 and 1775 whilst also testing Larcum Kendall's K1 chronometer as a method for measuring longitude.

Decline of the idea

Over the centuries the idea of Terra Australis gradually lost its hold. In 1616, Jacob Le Maire and Willem Schouten's rounding of Cape Horn proved that Tierra del Fuego was a relatively small island, while in 1642 Abel Tasman's first Pacific voyage proved that Australia was not part of the mythical southern continent. Much later, James Cook circumnavigated and charted New Zealand in 1770, showing that even it could not be part of a large continent. On his second voyage he circumnavigated the globe at a very high southern latitude, at some places even crossing the Antarctic Circle, showing that any possible southern continent must lie well within the cold polar areas. There could be no extension into regions with a temperate climate, as had been thought before. In 1814, Matthew Flinders published the book A Voyage to Terra Australis. Flinders had concluded that the Terra Australis as hypothesized by Aristotle and Ptolemy did not exist, so he wanted the name applied to what he saw as the next best thing: "Australia", replacing the former name for the continent, New Holland. He wrote:There is no probability, that any other detached body of land, of nearly equal extent, will ever be found in a more southern latitude; the name Terra Australis will, therefore, remain descriptive of the geographical importance of this country, and of its situation on the globe: it has antiquity to recommend it; and, having no reference to either of the two claiming nations, appears to be less objectionable than any other which could have been selected.
...with the accompanying note at the bottom of the page:Had I permitted myself any innovation upon the original term, it would have been to convert it into AUSTRALIA; as being more agreeable to the ear, and an assimilation to the names of the other great portions of the earth.

With the discovery of Antarctica his conclusion would soon be revealed as a mistake, but by that time the name had stuck.

The Province of Beach

A land feature known as the "Province of Beach" or "Boeach" – from the Latin Provincia boëach – appears to have resulted from mistranscriptions of a name in Marco Polo's Il Milione (Book III). Polo described his journey by sea from China to India by way of Champa (provincia ciamba; modern southern Vietnam),  Java Major, Locach (modern Lop Buri),   and Sumatra (Java Minor). In Cantonese, Lavo (an early name of Lop Buri) was pronounced "Lo-huk" 羅斛  and Locach was Marco Polo's transcription of this name. According to Polo, Locach was a kingdom where gold was "so plentiful that no one who did not see it could believe it". Polo's narrative describes the route southward from Champa toward Sumatra, but by a slip of the pen the name "Java" (which Polo did not himself visit) was substituted for "Champa" as the point of departure, thereby mis-locating Sumatra  and Locach south of Java (rather than Champa). Consequently, some geographers believed that Sumatra and Locach were near, or extensions of, Terra Australis.

In the German cursive script, Locach and Boeach look similar. A feature known as the "Province of Beach" or "Boeach" – from the Latin Provincia boëach – appears on European maps as early as the 15th century. On a map of the world published in Florence in 1489 by Henricus Martellus, the Latin name provincia boëach is given to a southern neighbour of Champa. In a 1532 edition of Marco Polo's Travels, Locach was changed to Boëach, later shortened to Beach.

By the mid-16th century, according to Henry Yule, the editor of a modern (1921) edition of Polo's Travels, some geographers and cartographers followed the error in older editions of Polo that "placed ... the land of "Boeach" (or Locac)" south-east of Java and "introduced in their maps a continent in that situation". Gerard Mercator did just that on his 1541 globe,  placing Beach provincia aurifera ("Beach the gold-bearing province") in the northernmost part of the Terra Australis in accordance with the faulty text of Marco Polo's Travels. The landmass of Beach remained in this location on Mercator's world map of 1569, with the amplified description, quoting Marco Polo, Beach provincia aurifera quam pauci ex alienis regionibus adeunt propter gentis inhumanitatem ("Beach the gold-bearing province, wither few go from other countries because of the inhumanity of its people") with Lucach regnum shown somewhat to its south west. Following Mercator, Abraham Ortelius also showed BEACH and LVCACH in these locations on his world map of 1571.

The 1596 map by Jan Huygen van Linschoten showed BEACH and LOCACH, projecting from the map's southern edge as the northernmost parts of the Terra Australis long hypothesized by Europeans. An encounter by the Dutch vessel Eendracht, commanded by Dirk Hartog, with Shark Bay, Western Australia in 1616, appeared to confirm that land existed where the maps showed Beach; Hartog named the wider  landmass Eendrachtsland, after his ship. In August 1642, the Council of the Dutch East India Company – evidently still relying on Linschoten's map – despatched Abel Tasman and Frans Jacobszoon Visscher on a voyage of exploration, of which one of the objects was to obtain knowledge of "all the totally unknown provinces of Beach".

In fiction

The unexplored southern continent was a frequent subject of fantastic fiction in the 17th and 18th centuries in the imaginary voyages genre. Among the works which dealt with imaginary visits to the continent (which at the time was still believed to be real) were:
  (1605), a satirical work by Joseph Hall, Bishop of Norwich;
 The Isle of Pines (1668) by the English politician Henry Neville;
  (1676) by Gabriel de Foigny;
  (1675) by the French Huguenot writer Denis Vairasse d'Allais.
  (, incorrectly dated 1710) by Simon Tyssot de Patot;
 : The Fortunate Shipwreck, or a description of New Athens in Terra Australis incognita (1720) by the English dramatist Thomas Killigrew;
 Relation d'un voyage du Pole Arctique, au Pole Antarctique par le centre du monde (1721), anonymous;
 Relation du royaume des Féliciens (1727) by the Marquis de Lassay;
 Viaggi di Enrico Wanton alle Terre incognite Australi (1749) by Zaccaria Seriman;
 Voyage de Robertson, aux Terres Australes, traduit sur le manuscrit anglois (1767), anonymous;
 La découverte australe par un homme-volant (1781) by Restif de la Bretonne;
 The idea of Terra Australis was also used by Terry Pratchett in his Discworld series of novels (1983–2014) where the World is balanced by the strange and little-known Counterweight Continent.

See also
 Early world maps
 Governorate of Terra Australis
 History of Antarctica
 Spanish colonization attempt of the Strait of Magellan

Notes

References

Further reading

 L. Ivanov and N. Ivanova. Terra Australis. In: The World of Antarctica. Generis Publishing, 2022. pp. 65–68.

Cartographic errors
European exploration of Australia
History of Australia (1788–1850)
History of Antarctica
Latin words and phrases
Maritime folklore
Theoretical continents
Articles containing video clips

Terra Australis


Philippe d'Orléans, Duke of Orléans (Louis Philippe Joseph; 13 April 1747 – 6 November 1793) commonly known as Philippe, was a member of the  House of Orléans. He actively supported the French Revolution and adopted the name Philippe Égalité, but was still guillotined during the Reign of Terror. His son Louis Philippe became King of the French after the July Revolution of 1830.  He held the rank of prince of the blood.

Biography
Louis Philippe was the son of Louis Philippe d'Orléans, Duke of Chartres, and Louise Henriette de Bourbon and was born at the Château de Saint Cloud.

Duke of Orléans
In November 1785, upon his father's death, Philippe, the new Duke of Orléans, became the head of the House of Orléans. This was one of the wealthiest families of France, and Premier Prince du Sang, addressed as Monsieur le Prince, the most important person of the kingdom after the king's immediate family. He was next in line to the throne should the main Bourbon line die out.

Marriage
On 6 June 1769, Louis Philippe married Louise Marie Adélaïde de Bourbon at the Chapel of the Palace of Versailles. Louise Marie Adélaïde brought to the already wealthy House of Orléans a considerable dowry of six million livres, an annual income of 240,000 livres (later increased to 400,000 livres), as well as lands, titles, residences and furniture. They had five children:

 Louis Philippe d'Orléans (later King Louis Philippe I of the French) (6 October 1773 – 26 August 1850) married Maria Amalia of Naples and Sicily.
 Antoine Philippe d'Orléans, Duke of Montpelier (3 July 1775 – 18 May 1807) died unmarried.
 Adélaïde d'Orléans, later made a "Princess of Orléans" (23 August 1777 – 31 December 1847) died unmarried.
 Françoise d'Orléans (twin sister of Adélaïde) (1777–1782) died young.
 Louis Charles d'Orléans, Count of Beaujolais (17 October 1779 – 30 May 1808) died unmarried.

During the first few months of their marriage, the couple appeared devoted to each other, but the duke went back to the life of "libertinage" he had led before his marriage. During the summer of 1772, a few months after his wife had given birth to a stillborn daughter, Philippe began a secret relationship with one of her ladies-in-waiting, Stéphanie Félicité Ducrest de St-Albin, Countess of Genlis. Stephanie was the niece of Madame de Montesson his fathers second wife.

Military service
In 1778, Philippe served in the squadron of the Count of Orvilliers. He was present in the Battle of Ushant, a naval battle against the British during the American War of Independence on 27 July 1778. He was removed from the navy due in part to the queen's hatred of him and also to his own incompetence and alleged cowardice. As compensation, he was given the honorary post of colonel-general of hussars.

Revolutionary Politics

The part Philippe d'Orléans played during the summer of 1789 is one of the most debated points in the history of the French Revolution. The royal court said he was at the bottom of every popular movement, and saw the "gold of Orléans" as the cause of the Réveillon riot and the storming of the Bastille. This was like the subsequent belief held by the Jacobins that everything opposing them relied on the "gold of Pitt the Younger"). His hatred of Marie Antoinette, his previous disgrace at court, and his liberalism (alongside his friendship with Duport and Choderlos de Laclos), all seem to point towards his involvement. The Duke is also said to have deliberately withheld grain from the people of Paris, being a direct cause of the 5 October "March on Versailles". The Duke is also thought to have lied about where he was when the Palace at Versailles was stormed in the early hours of the morning on the 6th of October. He said he was at the General Assembly in Paris, yet several witness (including the Marquise de la Tour du Pin) saw him lead the bloodthirsty mob to a staircase leading to the Queen's bedroom, protected by Swiss Guard. The mob cried "Long live our King d'Orléans" during the raid.

The Marquis de La Fayette, apparently jealous of Philippe's popularity, persuaded the king to send the duke to Britain on a mission, where he remained in England from October 1789 to July 1790. On 7 July 1790, he took his seat in the National Constituent Assembly. On 2 October, both he and Honoré Mirabeau were declared by the Assembly entirely free of any involvement in the events of 5–6 October 1789.

Citoyen Égalité
Philippe d'Orléans tried to keep himself distant from the political world, but he was still suspect to the King and subject to pressures from his supporters to replace Louis XVI. His lack of political aspirations could be proven by noting that he did not attempt to obtain any leading position after the King's flight to Varennes in June 1791. In fact, Louis Philippe attempted to reconcile with the King in January 1792, but was rejected, and refused to aid the King any further. In an attempt to show his support of democratic and Enlightenment philosophies, he changed his name to Philippe Citoyen Egalité, meaning equality.

This is clearly why Philippe now has his head hanging on a wall in the palace in France.

In the summer of 1792, he was present for a short time with the Army of the North, together with his two sons, the Duke of Chartres, future King of the French, and the Duke of Montpensier, but had returned to Paris before the insurrection of 10 August.

During the Grand Terror
After the fall of the monarchy, Philippe risked his own life by saving suspects of the revolutionary regime. At the request of Grace Elliott, he saved the life of Louis René Quentin de Richebourg de Champcenetz, the governor of the Tuileries Palace, who was his personal enemy. He accepted the title Citoyen Égalité given to him by the Commune.  He was elected 20th and last deputy for Paris to the National Convention, where he again made no notable contribution other than voting in the king's trial. He voted in support of the death sentence for Louis XVI. Many citizens of Paris saw this as an attempt by Philippe to overthrow the crown and take power himself.  They believed that not only was the Palais-Royal the center for revolutionary and philosophical debates, but that it was also his ground for recruiting and financing riots and rebellious activity.

As a member of the House of Bourbon, Louis Philippe was shortlisted for a trial, and effectively tried and guillotined in the space of one day on 6 November 1793. Accounts of his time in prison and execution mention his exceptional courage.

Philippe d'Orléans was buried in the Madeleine cemetery (closed in 1794), in Paris, where Louis XVI, Marie Antoinette and hundreds executed on the Place de la Révolution during the Terror had been buried.  His remains have never never found.

Titles and styles
13 April 1747 – 4 February 1752: His Most Serene Highness the Duke of Montpensier (Monseigneur le duc de Montpensier)
4 February 1752 – 18 November 1785: His Most Serene Highness the Duke of Chartres (Monseigneur le duc de Chartres)
18 November 1785 – 6 November 1793: His Most Serene Highness the Duke of Orléans (Monseigneur le duc d'Orléans)

References

1747 births
1793 deaths
People from Saint-Cloud
House of Orléans
Dukes and Duchesses of Chartres
Dukes and Duchesses of Orléans
Dukes and Duchesses of Nemours
Dukes and Duchesses of Montpensier
Dukes and Duchesses of Valois

Philippe Égalité


The swift is a bird in the family Apodidae. It is in the order Apodiformes with treeswifts and hummingbirds. The swift is very good at flying. It spends all of its time in the air.

The scientific name for the swift (apus) comes from the Ancient Greek word απους, apous which means "without feet". This is because swifts have very small, weak feet. Swifts use their feet to hold on to vertical places (for example, the wall of a house, or a cliff). Swifts do not want to land on the ground. It is often thought that if they land on ground, they cannot fly up again, but that is not true. They can take off but with difficulty.

Description
Swifts are small birds. They can fly very well and very fast. Some swifts can fly at 514m per second. If a swift needs to fly very fast, it can fly at 60m per second for a short amount of time. When catching insects, they fly in a series of swoops, changing direction rapidly as they pursue the prey.

Swifts have long, curved wings. The wings are in the shape of a sickle or boomerang. They have a forked tail. This means it looks like a V shape.

Swifts can be seen all over the world. They like to live in warmer places and they migrate every year. For example, Swifts fly to Europe in the spring and summer. When it gets cold at the start of autumn, the Swifts fly to Africa where it is warmer.

Nests

Swifts make their nests in a corner between two walls. For example, near the roof of a house, or in an area between rocks in a cave. They use mud and saliva (spit) to make a cup-shaped nest.

There are some swifts which only use saliva to make their nests. These swifts are in the genus Aerodramus. In Asia, people take the nests and use them to make bird's nest soup. This soup is very popular in China.

Apodiformes

Swift


Bryozoans, also known as the Polyzoa, Ectoprocta or moss animals, are a phylum of small aquatic animals living in colonies. The colonies usually have a skeleton of calcium carbonate. Bryozoans have a long fossil history, starting in the Ordovician. In their life-style they resemble the polyps which form coral. They generally like warm, tropical waters but live all over the world. There are about 5,000 living species, and 15,000 fossil species are known.

The colonies are formed by tiny (~0.2mm) members called zooids. They secrete tubes, usually of lime (CaCO3), sometimes of chitin, an organic compound. The zooids in a colony are all clones, produced by asexual reproduction. Despite this, most species produce different morphs: zooids with different functions.

All bryozoa have a lophophore. This is a ring of ten tentacles surrounding the mouth, each tentacle covered with cilia. When feeding, the zooid extends the lophophore outwards; when resting it is withdrawn into the mouth to protect it from predators.

Anatomy & physiology

Bryozoan skeletons grow in a variety of shapes and patterns: mound-shaped, lacy fans, branching twigs, and even corkscrew-shaped. Their skeletons have many tiny openings. Each opening is the home of zooid. They have a body with a U-shaped gut, opening at the mouth and at the anus. They feed with their lophophore. The tentacles of the bryozoans are ciliated. The beating of the cilia creates a current of water which drives food (mainly phytoplankton) towards the mouth. In some groups, notably some ctenostomes, a gizzard may be formed.

Bryozoans do not have a respiratory, or a blood system, because their small size allows diffusion of gases and nutrients. However, they do have a simple nervous system, and muscles, which together can quickly take the zooid down into its shelter.

One species of bryozoan, Bugula neritina, is of interest as a source of chemicals, bryostatins, which are under investigation as anti-cancer agents.

Reproduction & development
Bryozoans can reproduce both sexually and asexually. All Bryozoans, as far as is known, are hermaphrodite (meaning they are both male and female).

All members of a colony are clones: they are genetically identical, produced by asexual reproduction. This occurs by budding off new zooids from the first zooid. So the colony grows; this is the way a colony expands in size. If a piece of a bryozoan colony breaks off, the piece can continue to grow and will form a new colony.

All zooids in a colony are linked by strands of epithelial cells. The individual members of a colony, the zooids, are in some species generalised: they feed, and they can reproduce on occasion. But in most species the zooids are specialised to diffent functions. In this case the feeding zooids are called autozooids, and the non-feeding members are called heterozooids. Functions done by heterozooids include sexual reproduction, protection, locomotion, plumbing, structural support. The functions of some heterozooids is still unknown. The commonest function is that eggs are developed in brooding chambers (ovicells) on female or hermaphrodite heterozooids. There are variations in the details: sometimes a little complex of heterozooids produce larvae in a cooperative effort.p4

Another way to describe the bryozoa which develop heterozooids is to say they are polymorphic. This term is used in biology to describe the way a genetically unified population develops into clearly distinct forms. The polymorphism is usually controlled by genetic switching mechanisms, but in bryozoa there is little knowledge of their genetics.

Ecology

Most species of Bryozoan live in marine environments. There are about 50 species which inhabit freshwater. In their aquatic habitats, bryozoans live on all types of hard substrates: sand grains, rocks, shells, wood, blades of kelp, pipes and ships may be heavily encrusted with bryozoans. Some bryozoan colonies, however, do not grow on solid substrates, but form colonies on sediment. While some species live at depths of 8,200 m, most bryozoans live in much shallower water. Most bryozoans are sessile and immobile, but a few colonies are able to creep about, and a few species of non-colonial bryozoans live and move about in the spaces between sand grains. One remarkable species makes its living while floating in the Southern Ocean. Several bryozoan species live in the Midwestern United States, especially in Ohio, Indiana, and Kentucky which was once a part of a large ocean, the Western Interior Seaway.

Their diet consists of small microorganisms, including diatoms and other unicellular algae. In turn, bryozoans are preyed on by grazing organisms such as sea urchins and fish.

Bryozoans are almost entirely colony-forming animals. Many millions of individuals can form one colony. The colonies range from millimeters to meters in size, but the individuals that make up the colonies are tiny, usually less than a millimeter long. In each colony, different individuals have different functions. Some individuals gather up the food for the colony (autozooids), others depend on them (heterozooids). Some individuals are devoted to strengthening the colony (kenozooids), and still others to cleaning the colony (vibracula). There is only a single known solitary species, Monobryozoon ambulans, which does not form colonies.

Fossils

Fossil bryozoans first appear in the early Ordovician and had a huge adaptive radiation. They were abundant throughout the Palaeozoic era: they were one of the most dominant groups of Palaeozoic fossils. They were major components of seabed communities and, like modern-day bryozoans, played an important role in sediment stabilization and binding. They were food sources for many other benthic organisms. During the Lower Carboniferous (Mississippian) 354 to 323 million years ago, bryozoans were so common that their broken skeletons form entire limestone beds.

After a crash at the Permian/Triassic boundary, when almost all species went extinct, bryozoans recovered in the later Mesozoic to become as successful as before. The bryozoan fossil record has more than 15,000 species.

Most fossil bryozoans have mineralized skeletons. The skeletons of individual zooids vary from tubular to box-shaped and contain a terminal aperture from which the lophophore is protruded to feed. No pores are present in the great majority of Ordovician bryozoans, but skeletal evidence shows that epithelia were continuous from one zooid to the next.

One of the most important events during bryozoan evolution was the acquisition of a calcareous skeleton and the mechanism of tentacle protrusion. The rigidity of the outer body walls gave protection against predators, a greater degree of zooid connection, and the evolution of massive colony forms.

References

Other websites

Index to Bryozoa Bryozoa Home Page, was at RMIT; now bryozoa.net
Other Bryozoan WWW Resources
International Bryozoology Association official website
Bryozoan Introduction
Gordon Ramel The Phylum Ectoprocta (Bryozoa) (recommended)
Bryozoans  in the Connecticut River

Invertebrates
Animal phyla

Bryozoa


Heinrich Friedrich Füger (8 December 1751, in Heilbronn – 5 November 1818, in Vienna) was a German classicist portrait and historical painter.

Biography
Füger was a pupil of Nicolas Guibal in Stuttgart and of Adam Friedrich Oeser in Leipzig.  Afterward, he traveled and spent some time in Rome and Naples, where he painted frescoes in the Palazzo Caserta.  On his return to Vienna he was appointed court painter, professor, and vice-director of the Academy, and in 1806 director of the Belvedere Gallery.

Among his historical paintings are: The Farewell of Coriolanus (Czernin Gallery, Vienna), Allegory on the Peace of Vienna (1801), The Death of Germanicus (1789), The Assassination of Caesar, and Bathsheba (Budapest Gallery). Among his portraits are those of the Emperor Joseph II, the Grand Duchess Elizabeth Wilhelmine of Württemberg, Queen Caroline of Naples, and Horatio Nelson, who sat for him in Vienna in 1800 (National Portrait Gallery, London).  He painted in the classic style of Louis David and Anton Raphael Mengs and was inclined to be theatrical.

Füger was also a teacher; among his pupils was Gustav Philipp Zwinger, and Franciszek Ksawery Lampi.

Selected paintings

See also
 List of German painters

References

External links

Attribution:

18th-century German painters
18th-century German male artists
German male painters
19th-century German painters
19th-century German male artists
1751 births
1818 deaths
People from Heilbronn
Academic staff of the Academy of Fine Arts Vienna

Heinrich Füger


The Congo River (also known as Zaire River) is the largest river in Africa. Its overall length of 4,700 km (2,922 miles) makes it the second longest in Africa (after the Nile). The river and its tributaries flow through the second largest rain forest area in the world, second only to the Amazon Rainforest in South America.

The river also has the second-largest flow in the world, behind the Amazon, and the second-largest watershed of any river, again trailing the Amazon. Its watershed is a little larger than that of the Mississippi River. Because large parts of the river basin sit north and south of the equator, its flow is steady, as there is always at least one river having a rainy season.
The Congo gets its name from the old Kingdom of Kongo which was at the mouth of the river. The Democratic Republic of the Congo and the Republic of the Congo, both countries sitting along the river's banks, are named after it. From 1971 to 1997, the Democratic Republic of the Congo was called Zaire and its government called the river the Zaire River.

The sources of the Congo are in the Highlands and mountains of the East African Rift, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River.  This then becomes the Congo below Boyoma Falls.  The Chambeshi River in Zambia is usually taken as the source of the Congo because of the accepted practice worldwide of using the longest tributary, as with the Nile River.

The Congo flows mostly west from Kisangani just below the falls, then slowly bends southwest, passing by Mbandaka, joining with the Ubangi River, and running into the Pool Malebo (Stanley Pool). Kinshasa (formerly Léopoldville) and Brazzaville are on opposite sides of the river at the Pool, where the river narrows and falls through a few cataracts in deep canyons (collectively known as the Livingstone Falls), running by Matadi and Boma, and into the sea at the small town of Muanda.

History of exploration
The mouth of the Congo was visited by Europeans in 1482, by the Portuguese Diogo Cão, and in 1817, by a British exploration under James Kingston Tuckey that went up the river as far as Isangila. Henry Morton Stanley was the first European to travel along the whole river.

Economic importance
Although the Livingstone Falls stop ships coming in from the sea, almost all of the Congo is navigable in parts, especially between Kinshasa and Kisangani. Railways cross the three major falls that interrupt navigation, and much of the trade of central Africa passes along the river. Goods include copper, palm oil, sugar, coffee, and cotton. The river can also be valuable for hydroelectric power, and Inga Dams below Pool Malebo have been built.

In February of 2005, South Africa's state owned power company, Eskom, said that they had a proposal to increase the amount of electric power that the Inga can make through improvements and the building of a new hydroelectric dam. The project would bring the highest output of the dam to 40 GW, twice that of China's Three Gorges Dam.

Geological history
In the Mesozoic period before the continental drift opened the South Atlantic Ocean, the Congo was the upper part of a river about 12,000 km (7,500 miles) long that flowed west across the parts of Gondwanaland, now called Africa and South America.

Tributaries
Listed from down a river, to up a river:
 Inkisi
 Nzadi
 Nsele (south side of Pool Malebo)
 Bombo
 Kasai (between Fimi and Congo, known as Kwa)
 Fimi
 Lukenie
 Kwango
 Sankuru
 Likouala
 Sangha
 Ubangi
 Giri
 Uele
 Mbomou
 Luvua
 Luapula

Literature
The Congo River was the location the novel Heart of Darkness by Joseph Conrad.

References

Some reading
 Tim Butcher: Blood River - A Journey To Africa's Broken Heart, 2007.
 H. Winternitz, East Along the Equator: A Journey up the Congo and into Zaire (1987)

Other websites
 Bibliography on Water Resources and International Law  See Congo (or Zaïre) River. Peace Palace Library
 Information and a map of the Congo's watershed
 Map of the Congo River basin at Water Resources eAtlas

Rivers of Angola
Rivers of the Democratic Republic of the Congo
Rivers of the Republic of the Congo

Congo River


In computer networking, network address translation (NAT) is a technique of modifying the network address information in the IP packet headers while transferring the packet across a traffic routing device; such a technique remaps a given address space into another address space. This allows multiple computers to share a single public IPv4 address, which has become necessary because there are not enough IPv4 addresses for every computer in the world.

Today, NAT is used to hide networks (called network masquerading) or to hide IP (called IP masquerading). Masquerading is the mechanism that hides an entire address space, usually consisting of private network addresses (RFC 1918), behind a single IP address usually in the public domain address space.

The NAT mechanism is implemented inside a routing device that keeps track of the state of the network connections. The NAT device may also implement a firewall. The router uses translation tables to map the "hidden" addresses into a single address and then rewrites the outgoing IP packets on exit from the router so that they appear to originate from the router. In the reverse communications path, responses to the outgoing packets are mapped back to the originating IP address using the reverse of the rules ("state") stored in the translation tables. The outgoing IP packets establish the device translation tables.

The translation table rules established in the above way are cleared after a short period without new traffic refreshing their state. However, most NAT devices today allow the network administrator to configure translation tables' entries for permanent use. This feature is often referred to as "static NAT" or port forwarding and allows traffic originating in the 'outside' network to reach selected hosts in the masqueraded network.

Carrier-grade NAT, also called large-scale NAT, is NAT done by the Internet service provider (ISP). This is used when the ISP has more customers than IP addresses. This is commonly used by cellular service providers on 3G and 4G networks, but it is not (yet) common on landline DSL or cable connections. The CIDR address block 184.108.40.206/10 is reserved for carrier-grade NAT, although many ISPs improperly use RFC 1918 private addresses, which are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

NAT is used only in IPv4. It is not necessary in IPv6, because IPv6 has enough addresses for every computer in the world to have a global address.

Related pages
 Internet protocol suite
 Communications protocol

References

Internet

Network address translation


In computing, a video card, graphics card or graphics accelerator is a special circuit board that controls what is shown on a computer monitor and calculates 3D images and graphics.

A video card can be used to display a two-dimensional (2D) image like a desktop, or a three-dimensional (3D) image like a computer game. Computer-Aided Design (CAD) programs are often used by architects, engineers and designers to create 3D models on their computers. If a computer has a very fast video card, the user can create very detailed 3D models.

Most computers have a basic video and graphics capabilities built-in to the computer's motherboard.  These "integrated" video chips are not as fast as in separate or "discrete" video cards. Normally, they are fast enough for basic computer use and old or simple computer games on lower graphic settings. If a computer user wants faster and/or more detailed graphics, a video card can be installed.

Hardware
Video cards have their own processor (called a Graphics Processing Unit or GPU).  The GPU is distinct from the main computer processor (called the Central Processing Unit or CPU).  The CPU's job is to process the calculations needed to make the computer function.  The GPU's job is to handle graphics calculations.  3D graphics calculations take a lot of CPU power, so having a video card to handle the graphics calculations lets the CPU work on other things like running computer programs.

Video cards also have their own memory, separate from the main computer memory. It is usually much faster than main computer memory, too.  This helps the GPU do its graphics calculations even faster. Most video cards also can make one computer use more than one computer monitor at one time.  Graphics manufacturers Nvidia and AMD (Advanced Micro Devices) have special technologies that allow two identical cards to be linked together in a single computer for much faster performance. Nvidia calls their technology SLI and AMD calls their technology CrossFire. Some modern graphics cards can even process physics calculations to create even more realistic-looking 3D worlds.

Video cards typically connect to a motherboard using the Peripheral Component Interconnect (PCI), the Advanced Graphics Port (AGP) or the Peripheral Component Interconnect Express (PCI Express or PCI-E). PCI-E is the newest and fastest connection; which nearly all modern video cards and motherboards have this connection. Before PCI-E was used, AGP was the standard connection for video cards. Before AGP, video cards were designed for PCI (sometimes called "regular" PCI).

History
In early computing years, graphics processing was very basic and could be done by the CPU along with all the other processing. However, as computer games advanced and started using 3D graphics, the CPU had too much to do and CPU-makers could not keep up on making them faster.  Eventually, video cards, with their own GPU, were invented to solve this problem.  This lets the CPU do more of its own work since it does not have to spend any time on advanced graphics calculations; it can simply pass these calculations off to the GPU to be done.

The first video cards connected to the motherboard via the ISA connection.  The first popular non-IBM video cards were manufactured by a company called Hercules Computer Technology, Inc. Throughout the years, the importance of video cards has grown. As they evolved, a new connection standard was developed called Advanced Graphics Port (AGP). This was the first motherboard connection designed exclusively for video cards. It was much faster at transferring information between the video card and the rest of the computer. Eventually, the AGP connection became outdated, and a new connection, called PCI Express (PCI-E), became the standard for video cards. Most video cards manufactured today use PCI-E to connect to the motherboard.

Graphics cards

Video card


In cooking, a sauce is a liquid mixture added to another food for flavour. Sauces are not normally eaten by themselves; they add flavour, moisture, and visual appeal to another dish. Sauces are an essential element in cuisines all over the world.

The main sauces of French cuisine are built on a basis of roux, which is just flour and the liquid part of butter. Examples from Italian cuisine are the egg, cheese and ham sauce called Carbonara; the ground meat sauce called bolognese, and the herbs and garlic sauce called pesto.

Bottled sauces can be poured over food when it is served. An example would be the tomato-based sauce that is usually poured over spaghetti. Gravy is a brown sauce served with meat.

Sauce is a French word taken from the Latin salsus, meaning salted. Possibly the oldest sauce recorded is garum, the fish sauce used by the Romans.

Sauces need a liquid component, but some sauces (for example, pico de gallo salsa or chutney) may contain more solid elements than liquid.

Sauces may be used for savoury dishes or for desserts. They can be prepared and served cold, like mayonnaise, prepared cold but served lukewarm like pesto, or can be cooked like bechamel and served warm or again cooked and served cold like apple sauce.

Some sauces are commercial products like Worcestershire sauce, HP sauce, soy sauce or ketchup. In French cuisine they are freshly prepared by the chef. Sauces for salads are called salad dressing. A cook who specializes in making sauces is a saucier.

French cuisine

Sauces in French cuisine date back to the Middle Ages. There were hundreds of sauces in the culinary repertoire, and were a major defining characteristic of French cooking of the 19th and 20th centuries, until nouvelle cuisine.

In the 19th century, the chef Antonin Carême classified sauces into four families, each of which was based on a mother sauce (Also called grandes sauces). Carême's four mother sauces were:
 Béchamel, based on milk, thickened with a white roux.
 Espagnole, based on brown stock (usually veal), thickened with a brown roux.
 Velouté, based on a white stock, thickened with a blonde roux.
 Allemande, based on velouté sauce, is thickened with egg yolks and heavy cream.

In the early 20th century, the chef Auguste Escoffier updated this classification to five mother sauces. They are:
 Sauce Béchamel, Milk based sauce, thickened with a white roux.
 Sauce Velouté, White stock based sauce, thickened with a roux or a liaison.
 Sauce Tomate, Tomato based sauce, thickened with a roux.
 Sauce Espagnole, Roasted veal stock based sauce, thickened with a brown roux.
 Sauce Hollandaise, an emulsion of egg yolk, butter and lemon juice or vinegar. Béarnaise sauce (sauce béarnaise) is a "child" of hollandaise, meaning it is a variation on the theme.

A sauce which is based on one of the mother sauces is sometimes called a small sauce, minor sauce, or secondary sauce. Most sauces commonly used in classical cuisine are small sauces, or derivatives of one of the above-mentioned mother sauces.

Mother sauces are not commonly served as they are; instead they are augmented with additional ingredients to make small (derivative) sauces. For example, Bechamel can be made into Mornay by the addition of Gruyère or any cheese one may like, and Espagnole becomes Bordelaise with the addition and reduction of red wine, shallots, and poached beef marrow.

References

Sauce


A natural satellite in astronomy is a smaller body which moves around a larger body. The smaller body is held in orbit by gravitation. The term is used for moons which go around planets, and it is also used for small galaxies which orbit larger galaxies.

Bodies which orbit planets are called moons. They vary in size. The Earth has only one moon. Some other planets have many moons, and some have none. When people write just "the moon", they are usually talking about the moon of the Earth. Earth's moon is written with a capital letter, Moon. The Latin word for the moon is luna, which is why the adjective used to talk about the moon is "lunar". For example, lunar eclipse.

Anything that goes around a planet is called a satellite. Moons are natural satellites. People also use rockets to send machines into orbit around the Earth. These machines are called artificial (man-made) satellites.

Earth's moon

Moons do not make their own light. We can see the Earth's moon because it acts like a mirror, and reflects the light of the Sun.  The same half of the moon faces toward Earth at all times, no matter where it moves. This effect is called tidal locking. But different parts of the moon are lit up by the Sun, so it looks different at different times of the month. This change as seen from Earth is called the phases of the moon, or lunar phases.

A moon's cycle is the time the moon takes to change from looking very bright and round to looking very small and thin, and then back to bright and round again. In the case of the Earth's moon, this is about four weeks. It does this about 13 times in one year. The moon's cycle is about 28 days, a bit shorter than a calendar month.

The Apollo 11 mission helped Neil Armstrong and Buzz Aldrin become the first people to walk on the Moon. They did this on July 20, 1969.

Orbits
The orbit of a moon or other satellite is affected by two forces: gravity, and the centripetal force.
For example, the Earth's moon is kept in orbit by the gravitational pull from the Earth. This is also the way the Earth is attracted to the Sun, and stays in its orbit. The orbit of the Earth's moon actually causes the tides and waves on Earth.

Moons of moons

No moons that belong to moons have been found. In most cases, the tidal effects of the main body would make such a system unstable.

However, calculations completed after the recent finding  of a possible ring system around Saturn's moon Rhea show that Rhean orbits would be stable. The rings are thought to be narrow, something that is known with shepherd moons.

Asteroid moons
The finding of 243 Ida's moon Dactyl in the early 1990s was the proof that some asteroids have moons; indeed, 87 Sylvia has two. Some, such as 90 Antiope, are double asteroids with two same-sized parts.

Moons of the Solar System
The biggest moons in the Solar System (those bigger than about 3000 km across) are Earth's moon, Jupiter's Galilean moons (Io, Europa, Ganymede, and Callisto), Saturn's moon Titan, and Neptune's captured moon Triton.

The following is a table grouping the moons of the solar system by diameter. The column on the right has some notable planets, dwarf planets, asteroids, and Trans-Neptunian Objects for comparing.  It is normal for moons to be named after people from mythology.

Planets that have moons
Planets in our Solar System that have moon(s):
 Earth, 1 moon
 Mars, 2 moons
 Jupiter, 92 moons
 Saturn, 83 moons
 Uranus, 27 moons
 Neptune, 14 moons

Dwarf planets that have moons
 Orcus, 1 moon
 Pluto, 5 moons
 Haumea, 2 moons
 Quaoar, 1 moon
 Makemake, 1 moon
 Gonggong, 1 moon
 Eris, 1 moon

Planets not known to have moons
Planets in our Solar System that do not have moons:
 Mercury
 Venus
 Ceres
 Sedna

Galaxies
Galaxies are found in groups called galaxy clusters which are also held together by gravitation. Our own Milky Way is the second largest galaxy in our Local Group (the largest is Andromeda). Many smaller galaxies and star clusters are also held in the Local Group, outside the two main galaxies. They are all in orbits round one of the centres of gravity. That means most of them move round either Andromeda or the Milky Way. so it seems natural for astronomers to use the term 'satellite' for these as well.

Our Local Group is itself part of an even larger group, the Virgo Supercluster. There are other, even larger, groups of galaxies: see the Great Wall for an example.

References

Natural satellite