1.
Rotterdam
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Rotterdam is a city in the Netherlands, located in South Holland, within the Rhine–Meuse–Scheldt river delta at the North Sea. Its history goes back to 1270 when a dam was constructed in the Rotte river by people settled around it for safety, in 1340 Rotterdam was granted city rights by the Count of Holland and slowly grew into a major logistic and economic centre. Nowadays it is home to Europes largest port and has a population of 633,471, ranking second in the Netherlands, just behind Amsterdam. The Greater Rijnmond area is home to approximately 1.4 million people, Rotterdam is part of the yet larger Randstad conurbation with a total population of 7,100,000. The city of Rotterdam is known for the Erasmus University, riverside setting, lively cultural life, the near-complete destruction of Rotterdams city centre during World War II has resulted in a varied architectural landscape including sky-scrapers, which are an uncommon sight in other Dutch cities. Rotterdam is home to some world-famous architecture from renowned architects like Rem Koolhaas, Piet Blom, Ben van Berkel and others. Recently Rotterdam was listed eighth in The Rough Guide Top 10 Cities to Visit, the port of Rotterdam is the largest cargo port in Europe and the 10th largest in the world. Rotterdams logistic success is based on its location on the North Sea. The rivers Rhine, Meuse, and Scheldt give waterway access into the heart of Western Europe, the extensive distribution system including rail, roads, and waterways have earned Rotterdam the nickname Gateway to Europe, and, conversely, Gateway to the World in Europe. The settlement at the end of the fen stream Rotte dates from at least 900 CE. A dam on the Rotte or Rotterdam was built in the 1260s and was located at the present-day Hoogstraat, on 7 July 1340, Count Willem IV of Holland granted city rights to Rotterdam, which then had approximately 2,000 inhabitants. The port of Rotterdam grew slowly but steadily into a port of importance, becoming the seat of one of the six chambers of the Vereenigde Oostindische Compagnie, the greatest spurt of growth, both in port activity and population, followed the completion of the Nieuwe Waterweg in 1872. The city and harbor started to expand on the bank of the river. The Witte Huis or White House skyscraper, inspired by American office buildings and built in 1898 in the French Château-style, is evidence of Rotterdams rapid growth, when completed, it was the tallest office building in Europe, with a height of 45 m. During World War I the city was the worlds largest spy centre because of Dutch neutrality, many spies who were arrested and executed in Britain were led by German secret agents operating from Rotterdam. MI6 had its main European office on de Boompjes, from there the British coordinated espionage in Germany and occupied Belgium. In WWI an average of 25,000 Belgian refugees lived in the city, as well as hundreds of German deserters, during World War II, the German army invaded the Netherlands on 10 May 1940. Adolf Hitler had hoped to conquer the country in just one day, the Dutch army was finally forced to capitulate on 15 May 1940, following Hitlers bombing of Rotterdam on 14 May and threatening to bomb other Dutch cities
2.
Lieve Verschuier
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Lieve Pietersz Verschuier was a Dutch Golden Age painter of maritime subjects. He was born in Rotterdam, and is documented in Amsterdam in 1651 and he traveled to Rome in 1653 as a young man with Jan Vermeer van Utrecht and became friends with Willem Drost and Johann Carl Loth. On his return he settled in Rotterdam in 1667 where he remained, painting marine scenes and his maritime works are valued today for their historical value illustrating the art of shipbuilding in the 17th century
3.
Gottfried Kirch
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Gottfried Kirch was a German astronomer and the first Astronomer Royal in Berlin and, as such, director of the nascent Berlin Observatory. The son of Michael Kirch, a shoemaker in Guben, Electorate of Saxony, Initially he worked as a schoolmaster in Langgrün and he also worked as a calendar-maker in Saxonia and Franconia. He began to learn astronomy with Erhard Weigel in Jena, in Danzig in 1667, Kirch published calendars and built several telescopes and instruments. In 1679 he invented a screw micrometer for astronomical measurements and he became an astronomer working in Coburg, Leipzig and Guben as well as from 1700 in Berlin. In the last quarter of the 17th century, Kirch was the most-read calendar maker, in 1680 he discovered a comet with a telescope for the first time, Komet C/1680 V1, called Kirchs comet. In 1681 he discovered the Wild Duck Cluster M11, in 1686 he went to Leipzig. Together with the farmer and astronomer Christoph Arnold he observed the comets of that year, in the same year he discovered the Mira variable χ Cygni. He also dedicated time to observing the double star Mizar. Via Arnold he met his second wife Maria Margaretha Winkelmann, who had learnt astronomy from self-study, while jointly observing the comet of 1702, they discovered the globular cluster M5. In 1699, he had observed comet 55P/Tempel-Tuttle but this observation was not recognized until later analysis by Joachim Schubart, for a long period, he was unable to find employment, so he had to earn his living through the publication of Almanacs/ Calendars. He was assisted in the calculations by his wife and their children. A few series of almanacs appeared across several decades, for a time, he published up to 13 almanacs a year, a few appearing under pseudonyms and he also continued established almanacs from other authors under their name. It is only recently that the importance of the Kirchs Almanacs has been recognized for the distribution of ideas of the Enlightenment, the functions of almanacs are Information, Education and Discussion. Kirchs Calendars are marked additionally for the announcement of both their own results as well as the results from abroad, a few almanacs anticipate the Astronomisches Jahrbuch. Further aspects are the transmission of new ideas to people in conjunction with a growing distancing from astrological superstition. Since 1675 he pursued the idea of founding an Astronomical Society in Germany and it was to be open to all astronomers independent of nationality or religious persuasion. He projected the idea that all astronomers should send their observations to a location where they could be published as soon as possible. He considered Frankfurt am Main to be the location, for one because of the Messe
4.
Apsis
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An apsis is an extreme point in an objects orbit. The word comes via Latin from Greek and is cognate with apse, for elliptic orbits about a larger body, there are two apsides, named with the prefixes peri- and ap-, or apo- added to a reference to the thing being orbited. For a body orbiting the Sun, the point of least distance is the perihelion, the terms become periastron and apastron when discussing orbits around other stars. For any satellite of Earth including the Moon the point of least distance is the perigee, for objects in Lunar orbit, the point of least distance is the pericynthion and the greatest distance the apocynthion. For any orbits around a center of mass, there are the terms pericenter and apocenter, periapsis and apoapsis are equivalent alternatives. A straight line connecting the pericenter and apocenter is the line of apsides and this is the major axis of the ellipse, its greatest diameter. For a two-body system the center of mass of the lies on this line at one of the two foci of the ellipse. When one body is larger than the other it may be taken to be at this focus. Historically, in systems, apsides were measured from the center of the Earth. In orbital mechanics, the apsis technically refers to the distance measured between the centers of mass of the central and orbiting body. However, in the case of spacecraft, the family of terms are used to refer to the orbital altitude of the spacecraft from the surface of the central body. The arithmetic mean of the two limiting distances is the length of the axis a. The geometric mean of the two distances is the length of the semi-minor axis b, the geometric mean of the two limiting speeds is −2 ε = μ a which is the speed of a body in a circular orbit whose radius is a. The words pericenter and apocenter are often seen, although periapsis/apoapsis are preferred in technical usage, various related terms are used for other celestial objects. The -gee, -helion and -astron and -galacticon forms are used in the astronomical literature when referring to the Earth, Sun, stars. The suffix -jove is occasionally used for Jupiter, while -saturnium has very rarely used in the last 50 years for Saturn. The -gee form is used as a generic closest approach to planet term instead of specifically applying to the Earth. During the Apollo program, the terms pericynthion and apocynthion were used when referring to the Moon, regarding black holes, the term peri/apomelasma was used by physicist Geoffrey A. Landis in 1998 before peri/aponigricon appeared in the scientific literature in 2002
5.
Semi-major and semi-minor axes
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In geometry, the major axis of an ellipse is its longest diameter, a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis is one half of the axis, and thus runs from the centre, through a focus. Essentially, it is the radius of an orbit at the two most distant points. For the special case of a circle, the axis is the radius. One can think of the axis as an ellipses long radius. The semi-major axis of a hyperbola is, depending on the convention, thus it is the distance from the center to either vertex of the hyperbola. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction. Thus a and b tend to infinity, a faster than b, the semi-minor axis is a line segment associated with most conic sections that is at right angles with the semi-major axis and has one end at the center of the conic section. It is one of the axes of symmetry for the curve, in an ellipse, the one, in a hyperbola. The semi-major axis is the value of the maximum and minimum distances r max and r min of the ellipse from a focus — that is. In astronomy these extreme points are called apsis, the semi-minor axis of an ellipse is the geometric mean of these distances, b = r max r min. The eccentricity of an ellipse is defined as e =1 − b 2 a 2 so r min = a, r max = a. Now consider the equation in polar coordinates, with one focus at the origin, the mean value of r = ℓ / and r = ℓ /, for θ = π and θ =0 is a = ℓ1 − e 2. In an ellipse, the axis is the geometric mean of the distance from the center to either focus. The semi-minor axis of an ellipse runs from the center of the ellipse to the edge of the ellipse, the semi-minor axis is half of the minor axis. The minor axis is the longest line segment perpendicular to the axis that connects two points on the ellipses edge. The semi-minor axis b is related to the axis a through the eccentricity e. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction
6.
Astronomical unit
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The astronomical unit is a unit of length, roughly the distance from Earth to the Sun. However, that varies as Earth orbits the Sun, from a maximum to a minimum. Originally conceived as the average of Earths aphelion and perihelion, it is now defined as exactly 149597870700 metres, the astronomical unit is used primarily as a convenient yardstick for measuring distances within the Solar System or around other stars. However, it is also a component in the definition of another unit of astronomical length. A variety of symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union used the symbol A for the astronomical unit, in 2006, the International Bureau of Weights and Measures recommended ua as the symbol for the unit. In 2012, the IAU, noting that various symbols are presently in use for the astronomical unit, in the 2014 revision of the SI Brochure, the BIPM used the unit symbol au. In ISO 80000-3, the symbol of the unit is ua. Earths orbit around the Sun is an ellipse, the semi-major axis of this ellipse is defined to be half of the straight line segment that joins the aphelion and perihelion. The centre of the sun lies on this line segment. In addition, it mapped out exactly the largest straight-line distance that Earth traverses over the course of a year, knowing Earths shift and a stars shift enabled the stars distance to be calculated. But all measurements are subject to some degree of error or uncertainty, improvements in precision have always been a key to improving astronomical understanding. Improving measurements were continually checked and cross-checked by means of our understanding of the laws of celestial mechanics, the expected positions and distances of objects at an established time are calculated from these laws, and assembled into a collection of data called an ephemeris. NASAs Jet Propulsion Laboratory provides one of several ephemeris computation services, in 1976, in order to establish a yet more precise measure for the astronomical unit, the IAU formally adopted a new definition. Equivalently, by definition, one AU is the radius of an unperturbed circular Newtonian orbit about the sun of a particle having infinitesimal mass. As with all measurements, these rely on measuring the time taken for photons to be reflected from an object. However, for precision the calculations require adjustment for such as the motions of the probe. In addition, the measurement of the time itself must be translated to a scale that accounts for relativistic time dilation
7.
Orbital eccentricity
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The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is an orbit, values between 0 and 1 form an elliptical orbit,1 is a parabolic escape orbit. The term derives its name from the parameters of conic sections and it is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the galaxy. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit, the eccentricity of this Kepler orbit is a non-negative number that defines its shape. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola, radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits have zero angular momentum and hence eccentricity equal to one, keeping the energy constant and reducing the angular momentum, elliptic, parabolic, and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity. From Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros out of the center, from ἐκ- ek-, eccentric first appeared in English in 1551, with the definition a circle in which the earth, sun. Five years later, in 1556, a form of the word was added. The eccentricity of an orbit can be calculated from the state vectors as the magnitude of the eccentricity vector, e = | e | where. For elliptical orbits it can also be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p =1 −2 r a r p +1 where, rp is the radius at periapsis. For Earths annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈1.034 relative to center point of path, the eccentricity of the Earths orbit is currently about 0.0167, the Earths orbit is nearly circular. Venus and Neptune have even lower eccentricity, over hundreds of thousands of years, the eccentricity of the Earths orbit varies from nearly 0.0034 to almost 0.058 as a result of gravitational attractions among the planets. The table lists the values for all planets and dwarf planets, Mercury has the greatest orbital eccentricity of any planet in the Solar System. Such eccentricity is sufficient for Mercury to receive twice as much solar irradiation at perihelion compared to aphelion, before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit
Media related to Great Comet of 1680 at Wikimedia Commons
