In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth with the aid of optical telescopes. This occurs because the pair either forms a binary star or is an optical double, a chance line-of-sight alignment of two stars at different distances from the observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. Since the beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles between double stars to determine the relative motions of the pairs. If the relative motion of a pair determines a curved arc of an orbit, or if the relative motion is small compared to the common proper motion of both stars, it may be concluded that the pair is in mutual orbit as a binary star. Otherwise, the pair is optical. Multiple stars are studied in this way, although the dynamics of multiple stellar systems are more complex than those of binary stars.
The following are three types of paired stars: Optical doubles are unrelated stars that appear close together through chance alignment with Earth. Visual binaries are gravitationally-bound stars. Non-visual binaries are stars whose binary status was deduced through more esoteric means, such as occultation, spectroscopy, or anomalies in proper motion. Improvements in telescopes can shift non-visual binaries into visual binaries, as happened with Polaris A in 2006, it is only the inability to telescopically observe two separate stars that distinguish non-visual and visual binaries. Mizar, in Ursa Major, was observed to be double by Benedetto Galileo; the identification of other doubles soon followed: Robert Hooke discovered one of the first double-star systems, Gamma Arietis, in 1664, while the bright southern star Acrux, in the Southern Cross, was discovered to be double by Fontenay in 1685. Since that time, the search has been carried out and the entire sky has been examined for double stars down to a limiting apparent magnitude of about 9.0.
At least 1 in 18 stars brighter than 9.0 magnitude in the northern half of the sky are known to be double stars visible with a 36-inch telescope. The unrelated categories of optical doubles and true binaries are lumped together for historical and practical reasons; when Mizar was found to be a binary, it was quite difficult to determine whether a double star was a binary system or only an optical double. Improved telescopes and photography are the basic tools used to make the distinction. After it was determined to be a visual binary, Mizar's components were found to be spectroscopic binaries themselves. Observation of visual double stars by visual measurement will yield the separation, or angular distance, between the two component stars in the sky and the position angle; the position angle specifies the direction in which the stars are separated and is defined as the bearing from the brighter component to the fainter, where north is 0°. These measurements are called measures. In the measures of a visual binary, the position angle will change progressively and the separation between the two stars will oscillate between maximum and minimum values.
Plotting the measures in the plane will produce an ellipse. This is the projection of the orbit of the two stars onto the celestial sphere. Although it is expected that the majority of catalogued visual doubles are visual binaries, orbits have been computed for only a few thousand of the over 100,000 known visual double stars. Confirmation of a visual double star as a binary star can be achieved by observing the relative motion of the components. If the motion is part of an orbit, or if the stars have similar radial velocities or the difference in their proper motions is small compared to their common proper motion, the pair is physical; when observed over a short period of time, the components of both optical doubles and long-period visual binaries will appear to be moving in straight lines. Some bright visual double stars have a Bayer designation. In this case, the components may be denoted by superscripts. An example of this is α Crucis, whose components are α2 Crucis. Since α1 Crucis is a spectroscopic binary, this is a multiple star.
Superscripts are used to distinguish more distant, physically unrelated, pairs of stars with the same Bayer designation, such as α1,2 Capricorni, ξ1,2 Centauri, ξ1,2 Sagittarii. These optical pairs are resolvable by the naked eye. Apart from these pairs, the components of a double star are denoted by the letters A and B appended to the designation, of whatever sort, of the double star. For example, the components of α Canis Majoris are α Canis Majoris A and α Canis Majoris B; the letters AB may be used together to designate the pair. In the case of multiple stars, the letters C, D, so on may be used to denote additional components in order of increasing separation from the brightest star, A. Visual doubles are designated by an abbreviation for the name of their discoverer followed by a catalogue number unique to that observer. For example, the pair α Centauri AB was discovered by Father Ri
Photography is the art and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science and business, as well as its more direct uses for art and video production, recreational purposes and mass communication. A lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, electronically processed and stored in a digital image file for subsequent display or processing; the result with photographic emulsion is an invisible latent image, chemically "developed" into a visible image, either negative or positive depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either by using an enlarger or by contact printing.
The word "photography" was created from the Greek roots φωτός, genitive of φῶς, "light" and γραφή "representation by means of lines" or "drawing", together meaning "drawing with light". Several people may have coined the same new term from these roots independently. Hercules Florence, a French painter and inventor living in Campinas, used the French form of the word, photographie, in private notes which a Brazilian historian believes were written in 1834; this claim is reported but has never been independently confirmed as beyond reasonable doubt. The German newspaper Vossische Zeitung of 25 February 1839 contained an article entitled Photographie, discussing several priority claims – Henry Fox Talbot's – regarding Daguerre's claim of invention; the article is the earliest known occurrence of the word in public print. It was signed "J. M.", believed to have been Berlin astronomer Johann von Maedler. The inventors Nicéphore Niépce, Henry Fox Talbot and Louis Daguerre seem not to have known or used the word "photography", but referred to their processes as "Heliography", "Photogenic Drawing"/"Talbotype"/"Calotype" and "Daguerreotype".
Photography is the result of combining several technical discoveries, relating to seeing an image and capturing the image. The discovery of the camera obscura that provides an image of a scene dates back to ancient China. Greek mathematicians Aristotle and Euclid independently described a pinhole camera in the 5th and 4th centuries BCE. In the 6th century CE, Byzantine mathematician Anthemius of Tralles used a type of camera obscura in his experiments; the Arab physicist Ibn al-Haytham invented a camera obscura and pinhole camera. Leonardo da Vinci mentions natural camera obscura that are formed by dark caves on the edge of a sunlit valley. A hole in the cave wall will act as a pinhole camera and project a laterally reversed, upside down image on a piece of paper. Renaissance painters used the camera obscura which, in fact, gives the optical rendering in color that dominates Western Art, it is a box with a hole in it which allows light to go through and create an image onto the piece of paper.
The birth of photography was concerned with inventing means to capture and keep the image produced by the camera obscura. Albertus Magnus discovered silver nitrate, Georg Fabricius discovered silver chloride, the techniques described in Ibn al-Haytham's Book of Optics are capable of producing primitive photographs using medieval materials. Daniele Barbaro described a diaphragm in 1566. Wilhelm Homberg described how light darkened some chemicals in 1694; the fiction book Giphantie, published in 1760, by French author Tiphaigne de la Roche, described what can be interpreted as photography. Around the year 1800, British inventor Thomas Wedgwood made the first known attempt to capture the image in a camera obscura by means of a light-sensitive substance, he used paper or white leather treated with silver nitrate. Although he succeeded in capturing the shadows of objects placed on the surface in direct sunlight, made shadow copies of paintings on glass, it was reported in 1802 that "the images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver."
The shadow images darkened all over. The first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed in a attempt to make prints from it. Niépce was successful again in 1825. In 1826 or 1827, he made the View from the Window at Le Gras, the earliest surviving photograph from nature; because Niépce's camera photographs required an long exposure, he sought to improve his bitumen process or replace it with one, more practical. In partnership with Louis Daguerre, he worked out post-exposure processing methods that produced visually superior results and replaced the bitumen with a more light-sensitive resin, but hours of exposure in the camera were still required. With an eye to eventual commercial exploitation, the partners opted for total secrecy. Niépce died in 1833 and Daguerre redirected the experiments toward the light-sensitive silver halides, which Niépce had abandoned many years earlier because of his inability to make the images he captured with them light-fast and permanent.
National Library of the Czech Republic
The National Library of the Czech Republic is the central library of the Czech Republic. It is directed by the Ministry of Culture; the library's main building is located in the historical Clementinum building in Prague, where half of its books are kept. The other half of the collection is stored in the district of Hostivař; the National Library is the biggest library in the Czech Republic, in its funds there are around 6 million documents. The library has around 60,000 registered readers; as well as Czech texts, the library stores older material from Turkey and India. The library houses books for Charles University in Prague; the library won international recognition in 2005 as it received the inaugural Jikji Prize from UNESCO via the Memory of the World Programme for its efforts in digitising old texts. The project, which commenced in 1992, involved the digitisation of 1,700 documents in its first 13 years; the most precious medieval manuscripts preserved in the National Library are the Codex Vyssegradensis and the Passional of Abbes Kunigunde.
In 2006 the Czech parliament approved funding for the construction of a new library building on Letna plain, between Hradčanská metro station and Sparta Prague's football ground, Letná stadium. In March 2007, following a request for tender, Czech architect Jan Kaplický was selected by a jury to undertake the project, with a projected completion date of 2011. In 2007 the project was delayed following objections regarding its proposed location from government officials including Prague Mayor Pavel Bém and President Václav Klaus. Plans for the building had still not been decided in February 2008, with the matter being referred to the Office for the Protection of Competition in order to determine if the tender had been won fairly. In 2008, Minister of Culture Václav Jehlička announced the end of the project, following a ruling from the European Commission that the tender process had not been carried out legally; the library was affected by the 2002 European floods, with some documents moved to upper levels to avoid the excess water.
Over 4,000 books were removed from the library in July 2011 following flooding in parts of the main building. There was a fire at the library in December 2012. List of national and state libraries Official website
Leon Trotsky was a Russian revolutionary, Marxist theorist, Soviet politician whose particular strain of Marxist thought is known as Trotskyism. Supporting the Menshevik-Internationalists faction within the Russian Social Democratic Labour Party, he joined the Bolsheviks just before the 1917 October Revolution becoming a leader within the Communist Party, he would go on to become one of the seven members of the first Politburo, founded in 1917 to manage the Bolshevik Revolution. During the early days of the Russian Soviet Federative Socialist Republic and the Soviet Union, he served first as People's Commissar for Foreign Affairs and as the founder and commander of the Red Army, with the title of People's Commissar of Military and Naval Affairs, he became a major figure in the Bolshevik victory in the Russian Civil War. After leading a failed struggle of the Left Opposition against the policies and rise of Joseph Stalin in the 1920s and against the increasing role of bureaucracy in the Soviet Union, Trotsky was removed as Commissar for Military and Naval Affairs, removed from the Politburo, removed from the Central Committee, expelled from the Communist Party, exiled to Alma–Ata, exiled from the Soviet Union.
As the head of the Fourth International, Trotsky continued to oppose the Stalinist bureaucracy in the Soviet Union while in exile. Trotsky was assassinated in Mexico City by a Spanish-born NKVD agent. On 20 August 1940, Mercader attacked Trotsky with an ice axe and Trotsky died the next day in a hospital. Mercader acted upon instruction from Stalin and was nearly beaten to death by Trotsky's bodyguards, spent the next 20 years in a Mexican prison for the murder. Stalin presented Mercader with an Order of Lenin in absentia. Trotsky's ideas formed the basis of Trotskyism, a major school of Marxist thought that opposes the theories of Stalinism, he was written out of the history books under Stalin, was one of the few Soviet political figures, not rehabilitated by the government under Nikita Khrushchev in the 1950s. Leon Trotsky was born Lev Davidovich Bronstein on 7 November 1879, the fifth child of a Ukrainian-Jewish family of wealthy farmers in Yanovka or Yanivka, in the Kherson governorate of the Russian Empire, a small village 24 kilometres from the nearest post office.
His parents were his wife Anna Lvovna. Trotsky's father was born in Poltava, moved to Bereslavka, as it had a large Jewish community; the language spoken at home was a mixture of Ukrainian. Trotsky's younger sister, who grew up to be a Bolshevik and a Soviet politician, married the prominent Bolshevik Lev Kamenev; some authors, notably Robert Service, have claimed that Trotsky's childhood first name was the Yiddish Leiba. The American Trotskyist David North said that this was an assumption based on Trotsky's Jewish birth, contrary to Service's claims, there is no documentary evidence to support his using a Yiddish name, when that language was not spoken by his family. Both North and Walter Laqueur in their books say that Trotsky's childhood name was Lyova, a standard Russian diminutive of the name Lev. North has compared the speculation on Trotsky's given name to the undue emphasis given to his having a Jewish surname; when Trotsky was eight, his father sent him to Odessa to be educated. He was enrolled in a German-language school, which became Russified during his years in Odessa as a result of the Imperial government's policy of Russification.
As Isaac Deutscher notes in his biography of Trotsky, Odessa was a bustling cosmopolitan port city unlike the typical Russian city of the time. This environment contributed to the development of the young man's international outlook. Although Trotsky spoke French and German to a good standard, he said in his autobiography My Life that he was never fluent in any language but Russian and Ukrainian. Raymond Molinier wrote. Trotsky became involved in revolutionary activities in 1896 after moving to the harbor town of Nikolayev on the Ukrainian coast of the Black Sea. At first a narodnik, he opposed Marxism but was won over to Marxism that year by his future first wife, Aleksandra Sokolovskaya. Instead of pursuing a mathematics degree, Trotsky helped organize the South Russian Workers' Union in Nikolayev in early 1897. Using the name'Lvov,' he wrote and printed leaflets and proclamations, distributed revolutionary pamphlets, popularized socialist ideas among industrial workers and revolutionary students.
In January 1898, more than 200 members of the union, including Trotsky, were arrested. He was held for the next two years in prison awaiting trial, first in Nikolayev Kherson Odessa, in Moscow. In the Moscow prison he came into contact with other revolutionaries and heard about Lenin and read Lenin's book, The Development of Capitalism in Russia. Two months into his imprisonment, on 1–3 March 1898, the first Congress of the newly formed Russian Social Democratic Labor Party was held. From on Trotsky identified as a member of the party. While in the prison in Moscow, in the summer of 1899, Trotsky married Aleksandra Sokolovskaya, a fellow Marxist; the wedding ceremony was performed by a Jewish chaplain. In 1900, he was sentenced to four years in exile in Siberia; because of their marriage and his wife were allowed to be exiled to the same location
Sternberg Astronomical Institute
The Sternberg Astronomical Institute known as GAISh, is a research institution in Moscow, Russia, a division of Moscow State University. The institute is named after astronomer Pavel Karlovich Shternberg, it was founded in 1931, on the site of the observatory established by the university in 1831. The main-belt asteroid 14789 GAISH, discovered by Lyudmila Chernykh at the Crimean Astrophysical Observatory in 1969, was named in its honour; the official naming citation was published on 6 January 2007. Sternberg Astronomical Institute
Vladimir Ilyich Ulyanov, better known by the alias Lenin, was a Russian communist revolutionary and political theorist. He served as head of government of Soviet Russia from 1917 to 1922 and of the Soviet Union from 1922 to 1924. Under his administration and the wider Soviet Union became a one-party communist state governed by the Russian Communist Party. Ideologically a communist, he developed a variant of Marxism known as Leninism. Born to a moderately prosperous middle-class family in Simbirsk, Lenin embraced revolutionary socialist politics following his brother's 1887 execution. Expelled from Kazan Imperial University for participating in protests against the Russian Empire's Tsarist government, he devoted the following years to a law degree, he became a senior Marxist activist. In 1897, he was arrested for sedition and exiled to Shushenskoye for three years, where he married Nadezhda Krupskaya. After his exile, he moved to Western Europe, where he became a prominent theorist in the Marxist Russian Social Democratic Labour Party.
In 1903, he took a key role in a RSDLP ideological split, leading the Bolshevik faction against Julius Martov's Mensheviks. Encouraging insurrection during Russia's failed Revolution of 1905, he campaigned for the First World War to be transformed into a Europe-wide proletarian revolution, which as a Marxist he believed would cause the overthrow of capitalism and its replacement with socialism. After the 1917 February Revolution ousted the Tsar and established a Provisional Government, he returned to Russia to play a leading role in the October Revolution, in which the Bolsheviks overthrew the new regime. Lenin's Bolshevik government shared power with the Left Socialist Revolutionaries, elected soviets, a multi-party Constituent Assembly, although by 1918 it had centralised power in the new Communist Party. Lenin's administration redistributed land among the peasantry and nationalised banks and large-scale industry, it withdrew from the First World War by signing a treaty with the Central Powers and promoted world revolution through the Communist International.
Opponents were suppressed in the Red Terror, a violent campaign administered by the state security services. His administration defeated right and left-wing anti-Bolshevik armies in the Russian Civil War from 1917 to 1922 and oversaw the Polish–Soviet War of 1919–1921. Responding to wartime devastation and popular uprisings, in 1921 Lenin encouraged economic growth through the market-oriented New Economic Policy. Several non-Russian nations secured independence after 1917, but three re-united with Russia through the formation of the Soviet Union in 1922. In poor health, Lenin died at his dacha in Gorki, with Joseph Stalin succeeding him as the pre-eminent figure in the Soviet government. Considered one of the most significant and influential figures of the 20th century, Lenin was the posthumous subject of a pervasive personality cult within the Soviet Union until its dissolution in 1991, he became an ideological figurehead behind Marxism–Leninism and thus a prominent influence over the international communist movement.
A controversial and divisive individual, Lenin is viewed by supporters as a champion of socialism and the working class, while critics on both the left and right emphasize his role as founder and leader of an authoritarian regime responsible for political repression and mass killings. Lenin's father, Ilya Nikolayevich Ulyanov, was from a family of serfs. Despite this lower-class background he had risen to middle-class status, studying physics and mathematics at Kazan Imperial University before teaching at the Penza Institute for the Nobility. Ilya married Maria Alexandrovna Blank in mid-1863. Well educated and from a prosperous background, she was the daughter of a wealthy German–Swedish Lutheran mother, a Russian Jewish father who had converted to Christianity and worked as a physician, it is that Lenin was unaware of his mother's half-Jewish ancestry, only discovered by his sister Anna after his death. Soon after their wedding, Ilya obtained a job in Nizhny Novgorod, rising to become Director of Primary Schools in the Simbirsk district six years later.
Five years after that, he was promoted to Director of Public Schools for the province, overseeing the foundation of over 450 schools as a part of the government's plans for modernisation. His dedication to education earned him the Order of St. Vladimir, which bestowed on him the status of hereditary nobleman. Lenin was baptised six days later, he was one of eight children, having two older siblings and Alexander. They were followed by three more children, Olga and Maria. Two siblings died in infancy. Ilya was a devout member of the Russian Orthodox Church and baptised his children into it, although Maria—a Lutheran by upbringing—was indifferent to Christianity, a view that influenced her children. Both parents were monarchists and liberal conservatives, being committed to the emancipation reform of 1861 introduced by the reformist Tsar Alexander II; every summer they holidayed at a rural manor in Kokushkino. Among his siblings, Lenin was closest to his sister Olga, whom he bossed around.
Russia the Russian Federation, is a transcontinental country in Eastern Europe and North Asia. At 17,125,200 square kilometres, Russia is by far or by a considerable margin the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, the ninth most populous, with about 146.77 million people as of 2019, including Crimea. About 77 % of the population live in the European part of the country. Russia's capital, Moscow, is one of the largest cities in the world and the second largest city in Europe. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Estonia, Latvia and Poland, Ukraine, Azerbaijan, China and North Korea, it shares maritime borders with Japan by the Sea of Okhotsk and the U. S. state of Alaska across the Bering Strait. However, Russia recognises two more countries that border it, Abkhazia and South Ossetia, both of which are internationally recognized as parts of Georgia.
The East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' disintegrated into a number of smaller states; the Grand Duchy of Moscow reunified the surrounding Russian principalities and achieved independence from the Golden Horde. By the 18th century, the nation had expanded through conquest and exploration to become the Russian Empire, the third largest empire in history, stretching from Poland on the west to Alaska on the east. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Union of Soviet Socialist Republics, the world's first constitutionally socialist state; the Soviet Union played a decisive role in the Allied victory in World War II, emerged as a recognized superpower and rival to the United States during the Cold War.
The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction. Following the dissolution of the Soviet Union in 1991, twelve independent republics emerged from the USSR: Russia, Belarus, Uzbekistan, Azerbaijan, Kyrgyzstan, Tajikistan and the Baltic states regained independence: Estonia, Lithuania, it is governed as a federal semi-presidential republic. Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2018. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it one of the leading producers of oil and natural gas globally; the country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction.
Russia is a great power as well as a regional power and has been characterised as a potential superpower. It is a permanent member of the United Nations Security Council and an active global partner of ASEAN, as well as a member of the Shanghai Cooperation Organisation, the G20, the Council of Europe, the Asia-Pacific Economic Cooperation, the Organization for Security and Co-operation in Europe, the World Trade Organization, as well as being the leading member of the Commonwealth of Independent States, the Collective Security Treaty Organization and one of the five members of the Eurasian Economic Union, along with Armenia, Belarus and Kyrgyzstan; the name Russia is derived from Rus', a medieval state populated by the East Slavs. However, this proper name became more prominent in the history, the country was called by its inhabitants "Русская Земля", which can be translated as "Russian Land" or "Land of Rus'". In order to distinguish this state from other states derived from it, it is denoted as Kievan Rus' by modern historiography.
The name Rus itself comes from the early medieval Rus' people, Swedish merchants and warriors who relocated from across the Baltic Sea and founded a state centered on Novgorod that became Kievan Rus. An old Latin version of the name Rus' was Ruthenia applied to the western and southern regions of Rus' that were adjacent to Catholic Europe; the current name of the country, Россия, comes from the Byzantine Greek designation of the Rus', Ρωσσία Rossía—spelled Ρωσία in Modern Greek. The standard way to refer to citizens of Russia is rossiyane in Russian. There are two Russian words which are commonly