World War II
World War II known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries; the major participants threw their entire economic and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China, it included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, the only use of nuclear weapons in war. Japan, which aimed to dominate Asia and the Pacific, was at war with China by 1937, though neither side had declared war on the other. World War II is said to have begun on 1 September 1939, with the invasion of Poland by Germany and subsequent declarations of war on Germany by France and the United Kingdom.
From late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Finland and the Baltic states. Following the onset of campaigns in North Africa and East Africa, the fall of France in mid 1940, the war continued between the European Axis powers and the British Empire. War in the Balkans, the aerial Battle of Britain, the Blitz, the long Battle of the Atlantic followed. On 22 June 1941, the European Axis powers launched an invasion of the Soviet Union, opening the largest land theatre of war in history; this Eastern Front trapped most crucially the German Wehrmacht, into a war of attrition. In December 1941, Japan launched a surprise attack on the United States as well as European colonies in the Pacific. Following an immediate U. S. declaration of war against Japan, supported by one from Great Britain, the European Axis powers declared war on the U.
S. in solidarity with their Japanese ally. Rapid Japanese conquests over much of the Western Pacific ensued, perceived by many in Asia as liberation from Western dominance and resulting in the support of several armies from defeated territories; the Axis advance in the Pacific halted in 1942. Key setbacks in 1943, which included a series of German defeats on the Eastern Front, the Allied invasions of Sicily and Italy, Allied victories in the Pacific, cost the Axis its initiative and forced it into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained its territorial losses and turned toward Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in Central China, South China and Burma, while the Allies crippled the Japanese Navy and captured key Western Pacific islands; the war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union, culminating in the capture of Berlin by Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.
Following the Potsdam Declaration by the Allies on 26 July 1945 and the refusal of Japan to surrender under its terms, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August respectively. With an invasion of the Japanese archipelago imminent, the possibility of additional atomic bombings, the Soviet entry into the war against Japan and its invasion of Manchuria, Japan announced its intention to surrender on 15 August 1945, cementing total victory in Asia for the Allies. Tribunals were set up by fiat by the Allies and war crimes trials were conducted in the wake of the war both against the Germans and the Japanese. World War II changed the political social structure of the globe; the United Nations was established to foster international co-operation and prevent future conflicts. The Soviet Union and United States emerged as rival superpowers, setting the stage for the nearly half-century long Cold War. In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia.
Most countries whose industries had been damaged moved towards economic expansion. Political integration in Europe, emerged as an effort to end pre-war enmities and create a common identity; the start of the war in Europe is held to be 1 September 1939, beginning with the German invasion of Poland. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred and the two wars merged in 1941; this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935; the British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the fo
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
University of Königsberg
The University of Königsberg was the university of Königsberg in East Prussia. It was founded in 1544 as the world's second Protestant academy by Duke Albert of Prussia, was known as the Albertina. Following World War II, the city of Königsberg was transferred to the Soviet Union according to the 1945 Potsdam Agreement, renamed Kaliningrad in 1946; the Albertina was closed and the remaining German population expelled. Today, the Immanuel Kant Baltic Federal University in Kaliningrad claims to maintain the traditions of the Albertina. Albert, former Grand Master of the Teutonic Knights and first Duke of Prussia since 1525, had purchased a piece of land behind Königsberg Cathedral on the Kneiphof island of the Pregel River from the Samland chapter, where he had an academic gymnasium erected in 1542, he issued the deed of foundation of the Collegium Albertinum on 20 July 1544, after which the university was inaugurated on 17 August. The newly established Protestant duchy was a fiefdom of the Crown of the Kingdom of Poland and the university served as a Lutheran counterpart to the Catholic Cracow Academy.
Its first rector was son-in-law of Philipp Melanchthon. Lithuanian scholars Stanislovas Rapalionis and Abraomas Kulvietis were among the first professors of university. All professors had to take an oath on the Augsburg Confession. Since the Prussian lands lay beyond the borders of the Holy Roman Empire, both Emperor Charles V and Pope Paul III withheld their approval the Königsberg academy received the royal privilege by King Sigismund II Augustus of Poland on 28 March 1560. From 1618 the Prussian duchy was ruled in personal union by the Margraves of Brandenburg and in 1657 the "Great Elector" Frederick William of Brandenburg acquired full sovereignty over Prussia from Poland by the Treaty of Wehlau; the Albertina was the second oldest university and intellectual centre of Protestant Brandenburg-Prussia. It comprised four colleges: Theology, Medicine and Law also natural sciences. Subsequent rectors included numerous Hohenzollern Prussian royals, who had never been to the university represented by a prorector in charge of academic affairs.
The Prussian lands remained unharmed by the disastrous Thirty Years' War, which gained the Königsberg university an increasing popularity among students. In the 17th century, it was known as a home to Simon Dach, serving as rector in 1656/57, his fellow poets. Tsar Peter I of Russia visited the Albertina in 1697, leading to increased contacts between Prussia and the Russian Empire. Notable Russian students at Königbserg were Kirill Razumovsky president of the Russian Academy of Sciences and General Mikhail Andreyevich Miloradovich; the university and the city had profound impact on the development of Lithuanian culture. The first book in Lithuanian language was printed here in 1547 and several important Lithuanian writers attended the Albertina; the university was the preferred educational institution of the Baltic German nobility. The 18th century went down in cultural history as the "Königsberg Century" of Enlightenment, a heyday initiated by the Albertina student Johann Christoph Gottsched and continued by the philosopher Johann Georg Hamann and writer Theodor Gottlieb von Hippel the Elder.
Notable alumni were Johann Gottfried Herder, Zacharias Werner, Johann Friedrich Reichardt, E. T. A. Hoffmann, foremost the philosopher Immanuel Kant, rector in 1786 and 1788; these scholars laid the foundations for the Weimar Classicism and German Romanticism movements. The Albertina's magnificent botanical garden was inaugurated in 1811 during the Napoleonic Wars. Two years Friedrich Wilhelm Bessel established his outstanding observatory next door to the garden. Other university professors included such giants of the science world as the philosopher Johann Gottlieb Fichte, the biologist Karl Ernst von Baer, the mathematician Carl Gustav Jacobi, the mineralogist Franz Ernst Neumann and the physicist Hermann von Helmholtz. In the 19th and 20th centuries, the university was most famous for its school of Mathematics, founded by Carl Gustav Jacob Jacobi, continued by his pupils Ludwig Otto Hesse, Friedrich Richelot, Johann G. Rosenhain and Philipp Ludwig von Seidel, it was associated with the names of Hermann Minkowski, Adolf Hurwitz, Ferdinand von Lindemann and David Hilbert, one of the greatest modern mathematicians.
The mathematicians Alfred Clebsch and Carl Gottfried Neumann founded the Mathematische Annalen in 1868, which soon became the most influential mathematical journal of the time. Celebrating the university's 300 years jubilee 0n 31 August 1844, King Frederick William IV of Prussia laid the foundation for the new main building of the Albertina, inaugurated in 1862 by Crown Prince Frederick and Prorector Johann Karl Friedrich Rosenkranz; the building on central Paradeplatz was erected in a neo-Renaissance style according to plans designed by Friedrich August Stüler. The facade was adorned by an equestrian figure in relief of Albert of Prussia. Below it were niches containing statues of the Protestant reformers Martin Luther and Philipp Melanchthon. Inside was a handsome staircase, borne by marble columns; the Senate Hall contained a portrait of Emperor Frederick III by Lauchert and a bust of Immanuel Kant by Hagemann, a student of Schadow. The adjacent hall was adorned with frescoes painted in 1870.
The university library was situated on Mitteltragheim in 1901 and contained over 230,00
Hermann von Struve
Karl Hermann von Struve was a Russian astronomer. In Russian, his name is sometimes given as German Ottonovich Struve. Hermann von Struve was a part of the famous group of astronomers from the Struve family, which included his grandfather Friedrich Georg Wilhelm von Struve, father Otto Wilhelm von Struve, brother Ludwig Struve and nephew Otto Struve. Unlike other astronomers of the Struve family, Herman spent most of his career in Germany. Continuing the family tradition, Struve's research was focused on determining the positions of stellar objects, he was known for his work on satellites of planets of the Solar System and development of the intersatellite method of correcting their orbital position. The mathematical Struve function is named after him. Herman was born in 1854 in Tsarskoye Selo, a former Russian residence of the imperial family and visiting nobility, located 26 kilometers south from the center of St. Petersburg, he in 1872 entered the Tartu University. While studying there, in 1874–1875, Struve participated in an expedition to observe transit of Venus through the disk of the Sun.
That observation was carried out at Port Poisset on the Asiatic East Coast. After graduation in 1877, he became a member of the Pulkovo Observatory and was sent abroad for two-year post-graduate studies. Accompanied by his cousin's husband, Struve stayed in several cities, including Strasbourg, Milan and Berlin, learning from such celebrities as Helmholtz, Kirchhoff and Weierstrass. After returning to Russia, he joined the staff of Pulkovo Observatory, studying the satellites of Saturn among other things. In 1881, Struve obtained his master's degree at the University of Tartu, with the highest honors, in 1882 defended a PhD thesis at Saint Petersburg University. Both works were in the field of optics, in particular, the master thesis was titled "On Fresnel interference phenomenon – theoretical and experimental work" – according to Struve himself, despite the family traditions, he did not intend to become an astronomer. However, he became excited with his father's project of building a 30-inch telescope at Pulkovo, with its fantastic new possibilities for observation.
Struve made extensive use of this telescope in his work. In 1883, he was appointed adjunct astronomer at Pulkovo Observatory. By the Struve family was respected in Russia and Tsar Alexander III had a strong wish for Hermann to succeed his father Otto as the director of the Pulkovo Observatory. However, Hermann politely declined the offer, mentioning that he was in the middle of crucial observations of Saturn which would be interrupted by administrative tasks. In 1890, Struve was appointed as the senior astronomer at Pulkovo with the clear understanding that he should become director after completing his Saturn work. However, the death of Alexander III in 1894 freed Struve from this task. Pro-Russian views were developing in Russian society, including science, foreigners felt progressively more alienated. Therefore, when in 1895 Struve was offered the position of professor at Königsberg University, he gladly accepted and moved his family to Germany. There, he succeeded Wilhelm Julius Foerster as director of Königsberg Observatory.
Struve was called for the task of rescuing the Berlin Observatory. It was located in the center of Berlin where astronomy observations were not practical and rents were too high, discussions of its relocation stalled. Struve managed to sell the old observatory site so profitably that he could build a new observatory from scratch; the location was chosen at Neubabelsberg, near Potsdam and 25 kilometers from the center of Berlin, the new institution was named Berlin-Babelsberg Observatory. There, he started installing a 26-inch Zeiss refractor and a 48-inch reflector, which would become the largest telescope in Germany. While he did not get to operate them himself due to delays caused by World War I, the refractor was much used by his son Georg, the reflector by his lesser-known grandson Wilfried. In 1905, Struve became professor of the University of Berlin and from 1904 until his death in 1920, he served as director of the Berlin-Babelsberg Observatory. Struve's death was accelerated by a heart illness which he suffered from during his late years and by a bad fall from a tram car in 1919.
He broke a thigh, while recovering in a sanatorium in Bad Herrenalb, died of a heart attack. Whereas many colleagues described Struve as a stern and serious person, within his family, he was seen as a cultivated man, who enjoyed music and friends and was proud of the Struve family traditions, yet among relatives, he was known as inflexible in matters of principle. In 1885, Struve married the daughter of a cousin of his father, they had a son, Georg Otto Hermann, a daughter, Elisabeth. George was born on 29 December 1886 in Tsarskoye Selo and became a famous astronomer. Hermann's wife Eva Struve played an important role in rescuing his nephew Otto. After escaping from Soviet Russia in 1920, for a year and a half he was stranded penniless in Turkey. Otto wrote to his uncle for help, unaware of his death, but Eva asked assistance of Paul Guthnick, her late husband's successor at the Berlin-Babelsberg Observatory. Whereas Guthnick was not in a position to offer a job to Struve in Germany, he recommended Struve to the director of Yerkes Observatory in Chicago, who not only found a job for Struve at Yerkes, but arranged a visa for him and paid for his travel.
As with all astronomers of the Struve family, Herman was working on esta
Stellar parallax is the apparent shift of position of any nearby star against the background of distant objects. Created by the different orbital positions of Earth, the small observed shift is largest at time intervals of about six months, when Earth arrives at opposite sides of the Sun in its orbit, giving a baseline distance of about two astronomical units between observations; the parallax itself is considered to be half of this maximum, about equivalent to the observational shift that would occur due to the different positions of Earth and the Sun, a baseline of one astronomical unit. Stellar parallax is so difficult to detect that its existence was the subject of much debate in astronomy for hundreds of years, it was first observed in 1806 by Giuseppe Calandrelli who reported parallax in α-Lyrae in his work "Osservazione e riflessione sulla parallasse annua dall’alfa della Lira". In 1838 Friedrich Bessel made the first successful parallax measurement, for the star 61 Cygni, using a Fraunhofer heliometer at Königsberg Observatory.
Once a star's parallax is known, its distance from Earth can be computed trigonometrically. But the more distant an object is, the smaller its parallax. With 21st-century techniques in astrometry, the limits of accurate measurement make distances farther away than about 100 parsecs too approximate to be useful when obtained by this technique; this limits the applicability of parallax as a measurement of distance to objects that are close on a galactic scale. Other techniques, such as spectral red-shift, are required to measure the distance of more remote objects. Stellar parallax measures are given in the tiny units of arcseconds, or in thousandths of arcseconds; the distance unit parsec is defined as the length of the leg of a right triangle adjacent to the angle of one arcsecond at one vertex, where the other leg is 1 AU long. Because stellar parallaxes and distances all involve such skinny right triangles, a convenient trigonometric approximation can be used to convert parallaxes to distance.
The approximate distance is the reciprocal of the parallax: d ≃ 1 / p. For example, Proxima Centauri, whose parallax is 0.7687, is 1 / 0.7687 parsecs = 1.3009 parsecs distant. Stellar parallax is so small that its apparent absence was used as a scientific argument against heliocentrism during the early modern age, it is clear from Euclid's geometry that the effect would be undetectable if the stars were far enough away, but for various reasons such gigantic distances involved seemed implausible: it was one of Tycho Brahe's principal objections to Copernican heliocentrism that in order for it to be compatible with the lack of observable stellar parallax, there would have to be an enormous and unlikely void between the orbit of Saturn and the eighth sphere. James Bradley first tried to measure stellar parallaxes in 1729; the stellar movement proved too insignificant for his telescope, but he instead discovered the aberration of light and the nutation of Earth's axis, catalogued 3222 stars. Stellar parallax is most measured using annual parallax, defined as the difference in position of a star as seen from Earth and Sun, i.e. the angle subtended at a star by the mean radius of Earth's orbit around the Sun.
The parsec is defined as the distance. Annual parallax is measured by observing the position of a star at different times of the year as Earth moves through its orbit. Measurement of annual parallax was the first reliable way to determine the distances to the closest stars; the first successful measurements of stellar parallax were made by Friedrich Bessel in 1838 for the star 61 Cygni using a heliometer. Being difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century by use of the filar micrometer. Astrographs using astronomical photographic plates sped the process in the early 20th century. Automated plate-measuring machines and more sophisticated computer technology of the 1960s allowed more efficient compilation of star catalogues. In the 1980s, charge-coupled devices replaced photographic plates and reduced optical uncertainties to one milliarcsecond. Stellar parallax remains the standard for calibrating other measurement methods. Accurate calculations of distance based on stellar parallax require a measurement of the distance from Earth to the Sun, now known to exquisite accuracy based on radar reflection off the surfaces of planets.
The angles involved in these calculations are small and thus difficult to measure. The nearest star to the Sun, Proxima Centauri, has a parallax of 0.7687 ± 0.0003 arcsec. This angle is that subtended by an object 2 centimeters in diameter located 5.3 kilometers away. In 1989 the satellite Hipparcos was launched for obtaining parallaxes and proper motions of nearby stars, increasing the number of stellar parallaxes measured to milliarcsecond accuracy a thousandfold. So, Hipparcos is only able to measure parallax angles for stars up to about 1,600 light-years away, a little more than one percent of the diameter of the Milky Way Galaxy; the Hubble telescope WFC3 now has a precision of 20 to 40 microarcseconds, enabling reliable distance measurements u
Friedrich Wilhelm Bessel was a German astronomer, mathematician and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method of parallax. A special type of mathematical functions were named Bessel functions after Bessel's death, though they had been discovered by Daniel Bernoulli and generalised by Bessel. Bessel was born in Minden, administrative center of Minden-Ravensberg, as second son of a civil servant, he was born into a large family in Germany. At the age of 14 Bessel was apprenticed to the import-export concern Kulenkamp at Bremen; the business's reliance on cargo ships led him to turn his mathematical skills to problems in navigation. This in turn led to an interest in astronomy as a way of determining longitude. Bessel came to the attention of a major figure of German astronomy at the time, Heinrich Wilhelm Olbers, by producing a refinement on the orbital calculations for Halley's Comet in 1804, using old observation data taken from Thomas Harriot and Nathaniel Torporley in 1607.
Two years Bessel left Kulenkamp and became Johann Hieronymus Schröter's assistant at Lilienthal Observatory near Bremen. There he worked on James Bradley's stellar observations to produce precise positions for some 3,222 stars. In January 1810, at the age of 25, Bessel was appointed director of the newly founded Königsberg Observatory by King Frederick William III of Prussia. On the recommendation of fellow mathematician and physicist Carl Friedrich Gauss he was awarded an honorary doctor degree from the University of Göttingen in March 1811. Around that time, the two men engaged in an epistolary correspondence. However, when they met in person in 1825, they quarrelled. In 1842 Bessel took part in the annual meeting of the British Association for the Advancement of Science in Manchester, accompanied by the geophysicist Georg Adolf Erman and the mathematician Carl Gustav Jacob Jacobi. Bessel married Johanna, the daughter of the chemist and pharmacist Karl Gottfried Hagen, the uncle of the physician and biologist Hermann August Hagen and the hydraulic engineer Gotthilf Hagen, the latter Bessel's student and assistant from 1816 to 1818.
The physicist Franz Ernst Neumann, Bessel's close companion and colleague, was married to Johanna Hagen's sister Florentine. Neumann introduced Bessel's exacting methods of measurement and data reduction into his mathematico-physical seminar, which he co-directed with Carl Gustav Jacob Jacobi at Königsberg; these exacting methods had a lasting impact upon the work of Neumann's students and upon the Prussian conception of precision in measurement. Bessel had three daughters, his eldest daughter, married Georg Adolf Erman, member of the scholar family Erman. One of their sons was the renowned Egyptologist Adolf Erman. After several months of illness Bessel died in March 1846 at his observatory from retroperitoneal fibrosis. While the observatory was still in construction Bessel elaborated the Fundamenta Astronomiae based on Bradley's observations; as a preliminary result he produced tables of atmospheric refraction that won him the Lalande Prize from the French Academy of Sciences in 1811. The Königsberg Observatory began operation in 1813.
Starting in 1819, Bessel determined the position of over 50,000 stars using a meridian circle from Reichenbach, assisted by some of his qualified students. The most prominent of them was Friedrich Wilhelm Argelander. With this work done, Bessel was able to achieve the feat for which he is best remembered today: he is credited with being the first to use parallax in calculating the distance to a star. Astronomers had believed for some time that parallax would provide the first accurate measurement of interstellar distances—in fact, in the 1830s there was a fierce competition between astronomers to be the first to measure a stellar parallax accurately. In 1838 Bessel won the race. Given the current measurement of 11.4 ly, Bessel's figure had an error of 9.6%. Nearly at the same time Friedrich Georg Wilhelm Struve and Thomas Henderson measured the parallaxes of Vega and Alpha Centauri; as well as helping determine the parallax of 61 Cygni, Bessel's precise measurements using a new meridian circle from Adolf Repsold allowed him to notice deviations in the motions of Sirius and Procyon, which he deduced must be caused by the gravitational attraction of unseen companions.
His announcement of Sirius's "dark companion" in 1844 was the first correct claim of a unobserved companion by positional measurement, led to the discovery of Sirius B. Bessel was the first scientist who realized the effect called personal equation, that several observing persons determine different values recording the transition time of stars. In 1824, Bessel developed a new method for calculation the circumstances of eclipses using the so-called Besselian elements, his method simplified the calculation to such an extent, without sacrificing accuracy, that it is still in use today. Bessel's work in 1840 contributed to the discovery of Neptune in 1846 at Berlin Observatory, several months after Bessel's death. On Bessel's proposal the Prussian Academy of Sciences started the edition of the Berliner Akademische Sternkarten as an international project. One unpublished new chart enabled Johann Gottfried Galle to find Neptune near the position calculated by LeVerrier in 1846. In the second decade of the 19th century while studying the dynamics of'many-body' gravitational
Friedrich Wilhelm Argelander
Friedrich Wilhelm August Argelander was a German astronomer. He is known for his determinations of stellar brightnesses and distances. Argelander was born in Memel in the Kingdom of Prussia, the son of a father of Finnish descent, Johann Gottlieb Argelander, German mother, Dorothea Wilhelmina Grünlingen, he studied with Friedrich Bessel, obtained his Ph. D. in 1822 at University of Königsberg. From 1823 until 1837, Argelander was the head of the Finnish observatory, first in Turku and in Helsinki, he moved to Bonn, Germany. There he designed and built a new observatory at the University of Bonn with funding approved directly by King Frederick William IV whom Argelander had become friends with in his childhood. Argelander excelled in developing effective and fast methods for measuring star positions and magnitudes, thereby making a pioneering work for modern astronomy, he measured star distances with heliometers. His, his collaborators', great practical works of star cataloging and variable star research were made possible by the systematic usage of newly developed techniques.
Argelander was the first astronomer to begin a careful study of variable stars. Only a handful were known when he began, he was responsible for introducing the modern system of identifying them, he made a rough determination of the direction in which the Sun was moving. In 1842, he discovered that Groombridge 1830 had a high proper motion. For many decades its proper motion was the highest known. For a time, it was known as Argelander's Star. Together with Adalbert Krüger and Eduard Schönfeld, Argelander was responsible for the star catalogue known as the Bonner Durchmusterung, published between 1859 and 1862, which gave the positions and brightness of more than 324,000 stars, although it did not cover much of the southern half of the sky; this was the last star map to be published without the use of photography. In 1863, Argelander helped lead in the founding of an international organization of astronomers named the Astronomische Gesellschaft. Elected a foreign member of the Royal Swedish Academy of Sciences in 1846.
Elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1855. Elected Member of the Royal Academy of Science and Fine Arts of Belgium. Was awarded the Gold Medal of the Royal Astronomical Society in 1863. Orden Pour le Mérite für Wissenschaften und Künste in 1874; the three astronomical institutes of the Bonn University were merged and renamed as the Argelander-Institut für Astronomie in 2006. The crater Argelander on the Moon and the asteroid 1551 Argelander are named for him. Argelander, Friedrich Wilhelm. Untersuchung über die Bahn des grossen Cometen vom Jahre 1811, 4, Königsberg Asimov, Isaac. Asimov's Biographical Encyclopedia of Technology. Doubleday & Co. Inc. ISBN 0-385-17771-2. Sticker, Bernhard. "Argelander, Friedrich Wilhelm August". Dictionary of Scientific Biography. 1. New York: Charles Scribner's Sons. Pp. 240–243. ISBN 0-684-10114-9. Variable star designation Citations Works written by or about Friedrich Wilhelm Argelander at WikisourceGünther, Siegmund, "Argelander, Friedrich", Allgemeine Deutsche Biographie, 46, Leipzig: Duncker & Humblot, pp. 36–38 W.
T. L.. "Obituary". Monthly Notices of the Royal Astronomical Society. 36: 151–155. Bibcode:1876MNRAS..36..151.. Doi:10.1093/mnras/36.4.151. Retrieved 2008-05-20. Neue Uranometrie, 1843 - Full digital facsimile, Linda Hall Library. Uranometria nova, Berlin 1843