An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum; such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
The asteroid belt is the circumstellar disc in the Solar System located between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called minor planets; the asteroid belt is termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta and Hygiea; the total mass of the asteroid belt is 4% that of the Moon, or 22% that of Pluto, twice that of Pluto's moon Charon. Ceres, the asteroid belt's only dwarf planet, is about 950 km in diameter, whereas 4 Vesta, 2 Pallas, 10 Hygiea have mean diameters of less than 600 km; the remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, these can produce an asteroid family whose members have similar orbital characteristics and compositions.
Individual asteroids within the asteroid belt are categorized by their spectra, with most falling into three basic groups: carbonaceous and metal-rich. The asteroid belt formed from the primordial solar nebula as a group of planetesimals. Planetesimals are the smaller precursors of the protoplanets. Between Mars and Jupiter, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, instead of fusing together, the planetesimals and most of the protoplanets shattered; as a result, 99.9% of the asteroid belt's original mass was lost in the first 100 million years of the Solar System's history. Some fragments found their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs. Classes of small Solar System bodies in other regions are the near-Earth objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids, the Oort cloud objects.
On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres, the largest object in the asteroid belt. The detection was made by using the far-infrared abilities of the Herschel Space Observatory; the finding was unexpected because comets, not asteroids, are considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids." In 1596, Johannes Kepler predicted “Between Mars and Jupiter, I place a planet” in his Mysterium Cosmographicum. While analyzing Tycho Brahe's data, Kepler thought that there was too large a gap between the orbits of Mars and Jupiter. In an anonymous footnote to his 1766 translation of Charles Bonnet's Contemplation de la Nature, the astronomer Johann Daniel Titius of Wittenberg noted an apparent pattern in the layout of the planets. If one began a numerical sequence at 0 included 3, 6, 12, 24, 48, etc. doubling each time, added four to each number and divided by 10, this produced a remarkably close approximation to the radii of the orbits of the known planets as measured in astronomical units provided one allowed for a "missing planet" between the orbits of Mars and Jupiter.
In his footnote, Titius declared "But should the Lord Architect have left that space empty? Not at all."When William Herschel discovered Uranus in 1781, the planet's orbit matched the law perfectly, leading astronomers to conclude that there had to be a planet between the orbits of Mars and Jupiter. On January 1, 1801, Giuseppe Piazzi, chair of astronomy at the University of Palermo, found a tiny moving object in an orbit with the radius predicted by this pattern, he dubbed it "Ceres", after the Roman goddess of the patron of Sicily. Piazzi believed it to be a comet, but its lack of a coma suggested it was a planet. Thus, the aforementioned pattern, now known as the Titius–Bode law, predicted the semi-major axes of all eight planets of the time. Fifteen months Heinrich Olbers discovered a second object in the same region, Pallas. Unlike the other known planets and Pallas remained points of light under the highest telescope magnifications instead of resolving into discs. Apart from their rapid movement, they appeared indistinguishable from stars.
Accordingly, in 1802, William Herschel suggested they be placed into a separate category, named "asteroids", after the Greek asteroeides, meaning "star-like". Upon completing a series of observations of Ceres and Pallas, he concluded, Neither the appellation of planets nor that of comets, can with any propriety of language be given to these two stars... They resemble small stars so much. From this, their asteroidal appearance, if I take my name, call them Asteroids. By 1807, further investigation revealed two new objects in the region: Vesta; the burning of Lilienthal in the Napoleonic wars, where the main body of work had been done, brought this first period of discovery to a close. Despite Herschel's coinage, for several decades it remained common practice to refer to these objects as planets and to prefix t
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics and chemistry in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, stars, nebulae and comets. More all phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject is physical cosmology, the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences; the early civilizations in recorded history, such as the Babylonians, Indians, Nubians, Chinese and many ancient indigenous peoples of the Americas, performed methodical observations of the night sky. Astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, but professional astronomy is now considered to be synonymous with astrophysics. Professional astronomy is split into theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, analyzed using basic principles of physics.
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain observational results and observations being used to confirm theoretical results. Astronomy is one of the few sciences in which amateurs still play an active role in the discovery and observation of transient events. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets. Astronomy means "law of the stars". Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now distinct. Both of the terms "astronomy" and "astrophysics" may be used to refer to the same subject. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties," while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, dynamic processes of celestial objects and phenomena."
In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could be called astrophysics; some fields, such as astrometry, are purely astronomy rather than astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics" depending on whether the department is affiliated with a physics department, many professional astronomers have physics rather than astronomy degrees; some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, Astronomy and Astrophysics. In early historic times, astronomy only consisted of the observation and predictions of the motions of objects visible to the naked eye.
In some locations, early cultures assembled massive artifacts that had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye; as civilizations developed, most notably in Mesopotamia, Persia, China and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, the nature of the Sun and the Earth in the Universe were explored philosophically; the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Ptolemaic system, named after Ptolemy.
A important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the astronomical traditions that developed in many other civilizations. The Babylonians discovered. Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, he proposed a model of the Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and inven
Switzerland the Swiss Confederation, is a country situated in western and southern Europe. It consists of 26 cantons, the city of Bern is the seat of the federal authorities; the sovereign state is a federal republic bordered by Italy to the south, France to the west, Germany to the north, Austria and Liechtenstein to the east. Switzerland is a landlocked country geographically divided between the Alps, the Swiss Plateau and the Jura, spanning a total area of 41,285 km2. While the Alps occupy the greater part of the territory, the Swiss population of 8.5 million people is concentrated on the plateau, where the largest cities are to be found: among them are the two global cities and economic centres Zürich and Geneva. The establishment of the Old Swiss Confederacy dates to the late medieval period, resulting from a series of military successes against Austria and Burgundy. Swiss independence from the Holy Roman Empire was formally recognized in the Peace of Westphalia in 1648; the country has a history of armed neutrality going back to the Reformation.
It pursues an active foreign policy and is involved in peace-building processes around the world. In addition to being the birthplace of the Red Cross, Switzerland is home to numerous international organisations, including the second largest UN office. On the European level, it is a founding member of the European Free Trade Association, but notably not part of the European Union, the European Economic Area or the Eurozone. However, it participates in the Schengen Area and the European Single Market through bilateral treaties. Spanning the intersection of Germanic and Romance Europe, Switzerland comprises four main linguistic and cultural regions: German, French and Romansh. Although the majority of the population are German-speaking, Swiss national identity is rooted in a common historical background, shared values such as federalism and direct democracy, Alpine symbolism. Due to its linguistic diversity, Switzerland is known by a variety of native names: Schweiz. On coins and stamps, the Latin name – shortened to "Helvetia" – is used instead of the four national languages.
Switzerland is one of the most developed countries in the world, with the highest nominal wealth per adult and the eighth-highest per capita gross domestic product according to the IMF. Switzerland ranks at or near the top globally in several metrics of national performance, including government transparency, civil liberties, quality of life, economic competitiveness and human development. Zürich and Basel have all three been ranked among the top ten cities in the world in terms of quality of life, with the first ranked second globally, according to Mercer in 2018; the English name Switzerland is a compound containing Switzer, an obsolete term for the Swiss, in use during the 16th to 19th centuries. The English adjective Swiss is a loan from French Suisse in use since the 16th century; the name Switzer is from the Alemannic Schwiizer, in origin an inhabitant of Schwyz and its associated territory, one of the Waldstätten cantons which formed the nucleus of the Old Swiss Confederacy. The Swiss began to adopt the name for themselves after the Swabian War of 1499, used alongside the term for "Confederates", used since the 14th century.
The data code for Switzerland, CH, is derived from Latin Confoederatio Helvetica. The toponym Schwyz itself was first attested in 972, as Old High German Suittes perhaps related to swedan ‘to burn’, referring to the area of forest, burned and cleared to build; the name was extended to the area dominated by the canton, after the Swabian War of 1499 came to be used for the entire Confederation. The Swiss German name of the country, Schwiiz, is homophonous to that of the canton and the settlement, but distinguished by the use of the definite article; the Latin name Confoederatio Helvetica was neologized and introduced after the formation of the federal state in 1848, harking back to the Napoleonic Helvetic Republic, appearing on coins from 1879, inscribed on the Federal Palace in 1902 and after 1948 used in the official seal.. Helvetica is derived from the Helvetii, a Gaulish tribe living on the Swiss plateau before the Roman era. Helvetia appears as a national personification of the Swiss confederacy in the 17th century with a 1672 play by Johann Caspar Weissenbach.
Switzerland has existed as a state in its present form since the adoption of the Swiss Federal Constitution in 1848. The precursors of Switzerland established a protective alliance at the end of the 13th century, forming a loose confederation of states which persisted for centuries; the oldest traces of hominid existence in Switzerland date back about 150,000 years. The oldest known farming settlements in Switzerland, which were found at Gächlingen, have been dated to around 5300 BC; the earliest known cultural tribes of the area were members of the Hallstatt and La Tène cultures, named after the archaeological site of La Tène on the north side of Lake Neuchâtel. La Tène culture developed and flourished during the late Iron Age from around 450 BC under some influence from the Gree
Karl Schwarzschild Observatory
The Karl Schwarzschild Observatory is a German astronomical observatory in Tautenburg near Jena, Thuringia. It was founded in 1960 as an affiliated institute of the former German Academy of Sciences at Berlin and named in honour of the astronomer and physicist Karl Schwarzschild. In 1992, the institute was re-established as Thuringian State Observatory; the observatory has the largest telescope located in Germany, the largest Schmidt camera in the world. Made by VEB Zeiss Jena, this instrument is known as 2m Alfred Jensch Telescope: though its mirror is 2 metres in diameter, the telescope's aperture is 1.34m. The observatory has observed several exoplanets and brown dwarfs, as around the stars HD 8673, 30 Arietis, 4 Ursae Majoris, around HD 13189 on 5 April 2005; the observatory hosts an International station for the interferometric radio telescope LOFAR. Alfred Jensch Bernhard Schmidt Official website Interview with director on ESA's plans for finding Earth-like planets
Winterthur is a city in the canton of Zürich in northern Switzerland. It has the country's sixth-largest population, estimated at over 108,000 people, is the ninth largest agglomeration with about 138,000 inhabitants. Today Winterthur is a service and high-tech industrial satellite city within Greater Zürich, located about 20 kilometres northeast of downtown Zürich, only 20 minutes by train; the official language of Winterthur is German, but the main spoken language is the local variant of the Alemannic Swiss German dialect. Winterthur is abbreviated as Winti in the local dialect and by its inhabitants. Winterthur has links to Zürich Airport, it is a regional transport hub: the A1 motorway from Geneva through to St. Margrethen connects in Winterthur with the A4 motorway heading north toward Schaffhausen and the A7 motorway heading close to the Swiss-German border at Kreuzlingen. There are roads leading to other places such as Turbenthal; the railway station is one of the busiest railway stations in Switzerland.
Vitudurum was a vicus in. It was fortified into a castrum at the end of the 3rd century in reaction to the incipient Alamannic invasion. There was an Alamannic settlement on the site in the 7th century. In a battle near Winterthur in 919, Burchard II of Swabia asserted his control over the Thurgau within the Duchy of Swabia against the claims of Rudolph II of Burgundy; the counts of Winterthur, a cadet branch of the family of the counts of Bregenz, built Kyburg castle in the 10th century. With the extinction of the counts of Winterthur in 1053, the castle passed to the counts of Dillingen. Winterthur as a city was founded by Hartmann III of Dillingen in 1180, shortly before his death in the same year. From 1180 to 1263, Winterthur was ruled by the cadet line of the House of Kyburg; when the counts of Kyburg became extinct in the male line in 1263, Winterthur passed to the House of Habsburg, who established a comital line of Neu-Kyburg in 1264 and granted city rights to Winterthur in the same year.
From 1415 until 1442 Winterthur was reichsfrei. However, in the Old Zürich War they lost this freedom and came back under the control of the Austrian Habsburgs. Needing money, in 1467, the Habsburgs sold Winterthur to the city of Zürich. While it was under the leadership of Zürich, Winterthur's economic freedom was restricted, it lost the right to trade in some goods. This ended in 1798. On 27 May 1799, it was the site of the Battle of Winterthur between elements of the French Army of the Danube and elements of the Habsburg army, commanded by Friedrich, Baron von Hotze during the War of the Second Coalition, in the French Revolutionary Wars; because Winterthur lies near Zürich and at the junction of seven roads, the army that held the town held the access to most of Switzerland and points crossing the Rhine into southern Germany. Although the forces involved were small, the ability of the Austrians to sustain an 11-hour assault against the French line, on the plateau north of Zürich, resulted in the consolidation of three Austrian forces.
This led to the French defeat a few days later. In the 19th century, Winterthur became an industrial town when companies, like Sulzer, Rieter and SLM, built large industrial plants. Winterthur suffered from its investments in and guarantee of loans to the National Railway of Switzerland. In 1878, Winterthur had to sell its shares in the line, from 1881 to 1885 it was in great difficulties due to a loan of nine million francs guaranteed in 1874 by the town, together with three others in Aargau, to the enterprise; as the three co-guarantor towns were unable to pay their shares, the whole burden fell on Winterthur, which struggled to meet its liabilities. But it was assisted by large loans from the federal governments; the Great Depression, in the 1930s, hit Winterthur hard. 60% of the total employees in town worked in the machine industry. Jobs became hard to find. However, with the outbreak of World War II, industry grew again in the city. In 2008, Winterthur reached 100,000 inhabitants. Winterthur is located at an elevation of 439 meters.
The city is located in a basin south and east of the river Töss before it meets the High Rhine after 10 kilometres. The Eulach, a little river, flows from the town's east end through the middle of the town to meet the Töss at the west exit of the city; because of this the town is colloquially called "Eulachstadt". Zürich lies about 20 km southwest of Winterthur. Winterthur has an area of 68.1 km2. Of this area, 27 % is used for agricultural purposes. Of the rest of the land, 30.8% is settled and the remainder is non-productive. In 1996 housing and buildings made up 21.9% of the total area, while transportation infrastructure made up the rest. Of the total unproductive area, water made up 0.6% of the area. As of 2007, 27.6% of the total municipal area was undergoing some type of construction. Winterthur has seven city districts: 1 - Winterthur-Stadt, 2 - Oberwinterthur, 3 - Seen, 4 - Töss, 5 - Veltheim, 6 - Wülflingen, 7 - Mattenbach The City Council constitutes the executive government of the City of Winterthur and operates as a collegiate authority.
It is composed of each presiding over a department. Dep
Canton of Zürich
The canton of Zürich is a Swiss canton in the northeastern part of the country. With a population of 1,504,346, it is the most populated canton in the country.. Its capital is the city of Zürich; the official language is German. The local Swiss German dialect, called Züritüütsch, is spoken. In English the name of the canton and its capital is written without an umlaut; the Prehistoric pile dwellings around Zürichsee comprises 11 of total 56 Prehistoric pile dwellings around the Alps in Switzerland, that are located around Zürichsee in the cantons of Schwyz, St. Gallen and Zürich. Located on Zürichsee lakeshore, there are Freienbach–Hurden Rosshorn, Freienbach–Hurden Seefeld, Rapperswil-Jona/Hombrechtikon–Feldbach, Rapperswil-Jona–Technikum, Erlenbach–Winkel, Meilen–Rorenhaab, Wädenswil–Vorder Au, Zürich–Enge Alpenquai, Grosser Hafner and Kleiner Hafner; because the lake has grown in size over time, the original piles are now around 4 metres to 7 metres under the water level of 406 metres. On the small area of about 40 square kilometres around Zürichsee, there the settlements Greifensee–Storen/Wildsberg on Greifensee and Wetzikon–Robenhausen on Pfäffikersee lakeshore.
As well as being part of the 56 Swiss sites of the UNESCO World Heritage Site, each of these 11 prehistoric pile dwellings is listed as a Class object in the Swiss inventory of cultural property of national and regional significance. Zurihgauuia was a subdivision of Turgowe in the Duchy of Alamannia, consisting of the territory between Reuss and Töss. From the 740s, substantial portions of Zürichgau were owned by the Abbey of St. Gall. In c. 760, an administrative re-organisation under counts Ruthard and Warin exempted the castle town of Zürich from comital rule. A county of Zürichgau was established under Louis the Pious, for a count Ruadker, in 820. Zürichgau remained a nominally separate territory in the 9th century but was ruled by the same count as Thurgau. In 915, Zürichgau together with Thurgau fell to the Bucharding dukes of Swabia. In the late 10th century, the county of Zürich was ruled by the Nellenburger, during 1077–1172 by the Lenzburger. By the 13th century, Zürichgau was divided between the Habsburgs and the Kyburger, who held the territory west and east of Lake Zürich, respectively.
The territory of the canton of Zürich corresponds to the lands acquired by the city of Zürich after it became reichsfrei in 1218. Zürich pursued a policy of aggressive territorial expansion during the century following the revolution of the guilds in 1336. Zürich joined the Swiss Confederacy in 1351. Zürich lost the Toggenburg in the Old Zürich War of the 1440s; the northern parts up to the river Rhine came to the canton after the city of Zürich purchased Winterthur from the Habsburgs in 1468. In 1651, Zürich purchased Rafzerfeld from the counts of Sulz. At this point all of the territory of the modern canton was owned by Zürich. In the 18th century, the "inner bailiwicks" were under direct administration of city officials, while the "outer bailiwicks" were ruled by the reeves of Kyburg, Grüningen, Eglisau, Andelfingen, Wädenswil, Knonau; the city of Winterthur retained far-reaching autonomy. Zürichgau, the name of the medieval pagus, was in use for the territories of the city of Zürich during the 15th and 16th century.
Under the short-lived Helvetic Republic, the canton of Zürich became a purely administrative division. In 1803, some former possessions of Zürich to the west gained independence as part of the Canton of Aargau. In 1804 the Kantonspolizei Zürich was established as Landjäger-Corps des Kantons Zürich. A cantonal constitution was replaced in 1831 by a radical-liberal constitution; the Züriputsch, an armed uprising of the conservative rural population against the radical-liberal order, led to the dissolution of the cantonal government, a provisional conservative government was installed by colonel Paul Carl Eduard Ziegler. Under the threat of intervention of the other radical-liberal cantons of the Confederacy, the provisional government declared that the 1831 constitution would remain in effect. In a tumultuous session on 9 September 1839, the cantonal parliament declared its dissolution In the so-called Septemberregime, the newly elected cantonal government replaced all cantonal officials with conservatives, but it was again ousted by a radical-liberal election victory in 1844.
Alfred Escher was a member of the new cantonal parliament of 1844. The radical-liberal era of 1844–1868 was dominated by the so-called System Escher, a network of liberal politicians and industrialists built by Alfred Escher. Escher governed the canton in monarchical fashion, was popularly dubbed Alfred I. or Tsar of All Zürich. Escher controlled all cantonal institutions, at first with little political opposition, expunging all trace of the conservative takeover of 1839. Under Escher, the city of Zürich rose to the status of economic and financial center it still retains. Opposition against the dominance of Sytstem Escher increased after 1863. Th