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Alexander Vyssotsky
Alexander Nikolayevich Vyssotsky (russian: Алекса́ндр Никола́евич Высо́тский, 23 May 1888 – 31 December 1973) was a Russian-American astronomer. Born in Moscow, in 1923 he moved to the United States, where he eventually became professor at the University of Virginia and vice-president of the American Astronomical Society. During his 35 years at the McCormick Observatory of the University of Virginia, he was sequentially promoted from instructor to assistant professor in 1928, and to professor in 1937. His best known work is probably a catalog with five lists of stars titled ''Dwarf M Stars Found Spectrophotometrically''. This work was important because it was the first list of nearby stars identified not by their motions in the sky, but by their intrinsic, spectroscopic, characteristics. Until this time, most nearby stars had been identified by their large proper motions; however, not all stars close to the Sun have a large proper motion, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russian Empire
The Russian Empire was an empire and the final period of the Russian monarchy from 1721 to 1917, ruling across large parts of Eurasia. It succeeded the Tsardom of Russia following the Treaty of Nystad, which ended the Great Northern War. The rise of the Russian Empire coincided with the decline of neighbouring rival powers: the Swedish Empire, the Polish–Lithuanian Commonwealth, Qajar Iran, the Ottoman Empire, and Qing China. It also held colonies in North America between 1799 and 1867. Covering an area of approximately , it remains the third-largest empire in history, surpassed only by the British Empire and the Mongol Empire; it ruled over a population of 125.6 million people per the 1897 Russian census, which was the only census carried out during the entire imperial period. Owing to its geographic extent across three continents at its peak, it featured great ethnic, linguistic, religious, and economic diversity. From the 10th–17th centuries, the land ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism (optics)
An optical prism is a transparent optics, optical element with flat, polished surfaces that are designed to refraction, refract light. At least one surface must be angled — elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are prism (geometry), geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic glass, acrylic and fluorite#Optics, fluorite. A dispersive prism can be used to break white#White light, white light up into its constituent spectral colors (the colors of the rainbow) as described in the following section. Other types of prisms noted below can be used to reflection (physics), reflect light, or to split light into components with different polarization (w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Scientist
A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus (although there is overlap). Although computer scientists can also focus their work and research on specific areas (such as algorithm and data structure development and design, software engineering, information theory, database theory, computational complexity theory, numerical analysis, programming language theory, computer graphics, and computer vision), their foundation is the theoretical study of computing from which these other fields derive. A primary goal of computer scientists is to develop or validate models, often mathematical, to describe the properties of computational systems (processors, programs, computers interacting with people, computers interacting with other computers, etc.) with an overall objective of discovering des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History One of the earliest known mathematicians were Thales of Miletus (c. 624–c.546 BC); he has been hailed as the first true mathematician and the first known individual to whom a mathematical discovery has been attributed. He is credited with the first use of deductive reasoning applied to geometry, by deriving four corollaries to Thales' Theorem. The number of known mathematicians grew when Pythagoras of Samos (c. 582–c. 507 BC) established the Pythagorean School, whose doctrine it was that mathematics ruled the universe and whose motto was "All is number". It was the Pythagoreans who coined the term "mathematics", and with whom the study of mathematics for its own sake begins. The first woman mathematician recorded by history was Hypati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emma Vyssotsky
Emma Vyssotsky (October 23, 1894 – May 12, 1975, née Emma T. R. Williams) was an American astronomer who was honored with the Annie J. Cannon Award in Astronomy in 1946. Biography Emma earned her bachelor's degree in mathematics at Swarthmore College in 1916 (also available oarchive.org/ref> and worked at Smith College as an astronomy/mathematics demonstrator for a year before finding work at an insurance company as an actuary. In 1927, after receiving a Whitney Fellowship and a Bartol Scholarship, she enrolled in astronomy at Radcliffe College (now part of Harvard). There, she worked with Cecilia Payne on the "spectral line contours of hydrogen and ionized calcium throughout the spectral sequence." Emma received her PhD in astronomy from Harvard College in 1930 for her dissertation titled, ''A Spectrophotometric Study of A Stars''. At the time, she was only the third individual to be awarded a PhD in astronomy from Harvard. She followed her husband, astronomer Alexander N. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunisia
) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , coordinates = , official_languages = Arabic Translation by the University of Bern: "Tunisia is a free State, independent and sovereign; its religion is the Islam, its language is Arabic, and its form is the Republic." , religion = , languages_type = Spoken languages , languages = Minority Dialects : Jerba Berber (Chelha) Matmata Berber Judeo-Tunisian Arabic (UNESCO CR) , languages2_type = Foreign languages , languages2 = , ethnic_groups = * 98% Arab * 2% Other , demonym = Tunisian , government_type = Unitary presidential republic , leader_title1 = President , leader_name1 = Kais Saied , leader_ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with a East Thrace, small portion on the Balkans, Balkan Peninsula in Southeast Europe. It shares borders with the Black Sea to the north; Georgia (country), Georgia to the northeast; Armenia, Azerbaijan, and Iran to the east; Iraq to the southeast; Syria and the Mediterranean Sea to the south; the Aegean Sea to the west; and Greece and Bulgaria to the northwest. Cyprus is located off the south coast. Turkish people, Turks form the vast majority of the nation's population and Kurds are the largest minority. Ankara is Turkey's capital, while Istanbul is its list of largest cities and towns in Turkey, largest city and financial centre. One of the world's earliest permanently Settler, settled regions, present-day Turkey was home to important Neol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
October Revolution
The October Revolution,. officially known as the Great October Socialist Revolution. in the Soviet Union, also known as the Bolshevik Revolution, was a revolution in Russia led by the Bolshevik Party of Vladimir Lenin that was a key moment in the larger Russian Revolution of 1917–1923. It was the second revolutionary change of government in Russia in 1917. It took place through an armed insurrection in Petrograd (now Saint Petersburg) on . It was the precipitating event of the Russian Civil War. The October Revolution followed and capitalized on the February Revolution earlier that year, which had overthrown the Tsarist autocracy, resulting in a liberal provisional government. The provisional government had taken power after being proclaimed by Grand Duke Michael, Tsar Nicholas II's younger brother, who declined to take power after the Tsar stepped down. During this time, urban workers began to organize into councils (soviets) wherein revolutionaries criticized the pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fighting occurring throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died in genocides within the Ottoman Empire and in the 1918 influenza pandemic, which was exacerbated by the movement of combatants during the war. Prior to 1914, the European great powers were divided between the Triple Entente (comprising France, Russia, and Britain) and the Triple Alliance (containing Germany, Austria-Hungary, and Italy). Tensions in the Balkans came to a head on 28 June 1914, following the assassination of Archduke Franz Ferdin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or dwarf stars. These are the most numerous true stars in the universe and include the Sun. After condensation and ignition of a star, it generates thermal energy in its dense core region through nuclear fusion of hydrogen into helium. During this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass but also based on its chemical composition and age. The cores of main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Gravity
The surface gravity, ''g'', of an astronomical object is the gravitational acceleration experienced at its surface at the equator, including the effects of rotation. The surface gravity may be thought of as the acceleration due to gravity experienced by a hypothetical test particle which is very close to the object's surface and which, in order not to disturb the system, has negligible mass. For objects where the surface is deep in the atmosphere and the radius not known, the surface gravity is given at the 1 bar pressure level in the atmosphere. Surface gravity is measured in units of acceleration, which, in the SI system, are meters per second squared. It may also be expressed as a multiple of the Earth's standard surface gravity, which is equal to :''g'' = In astrophysics, the surface gravity may be expressed as log ''g'', which is obtained by first expressing the gravity in cgs units, where the unit of acceleration and surface gravity is centimeters per seco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
