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Fundamental Station
The term fundamental station is used for special observatories which combine several space positioning techniques like VLBI, satellite laser ranging, GPS, Glonass, etc. They are the basis of plate tectonic analysis, allowing the monitoring of continental drift rates with millimetre accuracies. A fundamental point is the geometric origin of a geodetic network and defines the datum (geodesy), geodetic datum of a national survey. Some fundamental stations are an astronomical or satellite geodetic observatory. In any case, the geographic latitude and longitude of the station is precisely determined by methods of astrogeodesy and is chosen as ellipsoidal latitude and longitude at the Earth ellipsoid which is used to calculate the coordinates of the whole network. Also, precise azimuths to one or two network points are observed, and are taken over as orientated Direction (geometry), directions of these network lines. By these procedure, the polar axis of the reference ellipsoid becomes p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the ''Timaeus'' of Plato, or Socrates in his reflections on what the Greeks called ''khôra'' (i.e. "space"), or in the ''Physics'' of Aristotle (Book IV, Delta) in the definition of ''topos'' (i.e. place), or in the later "geometrical conception of place" as "spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth Rotation
Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Polaris, Earth turns counterclockwise. The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where Earth's axis of rotation meets its surface. This point is distinct from Earth's North Magnetic Pole. The South Pole is the other point where Earth's axis of rotation intersects its surface, in Antarctica. Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes and 4 seconds with respect to other distant stars ( see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern day is longer by about 1.7 milli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inertial System
In classical physics and special relativity, an inertial frame of reference (also called inertial reference frame, inertial frame, inertial space, or Galilean reference frame) is a frame of reference that is not undergoing any acceleration. It is a frame in which an isolated physical object — an object with zero net force acting on it — is perceived to move with a constant velocity (it might be a zero velocity) or, equivalently, it is a frame of reference in which Newton's first law of motion holds. All inertial frames are in a state of constant, rectilinear motion with respect to one another; in other words, an accelerometer moving with any of them would detect zero acceleration. It has been observed that celestial objects which are far away from other objects and which are in uniform motion with respect to the cosmic microwave background radiation maintain such uniform motion. Measurements in one inertial frame can be converted to measurements in another by a simp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Celestial Reference System
The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU). Its origin is at the barycenter of the Solar System, with axes that are intended to "show no global rotation with respect to a set of distant extragalactic objects". This fixed reference system differs from previous reference systems, which had been based on Catalogues of Fundamental Stars that had published the positions of stars based on direct "observations of heir equatorial coordinates, right ascension and declination" and had adopted as "privileged axes ... the mean equator and the dynamical equinox" at a particular date and time. The International Celestial Reference Frame (ICRF) is a realization of the International Celestial Reference System using reference celestial sources observed at radio wavelengths. In the context of the ICRS, a reference ''frame'' (RF) is the physical realization of a reference ''system,'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Terrestrial Reference System
The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface. This is done in much the same way that a physical standard might be described as a set of procedures for creating a ''realization'' of that standard. The ITRS defines a geocentric system of coordinates using the SI system of measurement. An International Terrestrial Reference Frame (ITRF) is a realization of the ITRS. Its origin is at the center of mass of the whole earth including the oceans and atmosphere. New ITRF solutions are produced every few years, using the latest mathematical and surveying techniques to attempt to realize the ITRS as precisely as possible. Due to experimental error, any given ITRF will differ very slightly from any other realization of the ITRF. The difference between the latest as of 2006 WGS 84 (frame realisation G1150) and the latest ITRF2000 is only a few centimeters and RMS diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordinate System
In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is significant, and they are sometimes identified by their position in an ordered tuple and sometimes by a letter, as in "the ''x''-coordinate". The coordinates are taken to be real numbers in elementary mathematics, but may be complex numbers or elements of a more abstract system such as a commutative ring. The use of a coordinate system allows problems in geometry to be translated into problems about numbers and ''vice versa''; this is the basis of analytic geometry. Common coordinate systems Number line The simplest example of a coordinate system is the identification of points on a line with real numbers using the ''number line''. In this system, an arbitrary point ''O'' (the ''origin'') is chosen on a given line. The coordinate of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commonwealth Of Independent States
The Commonwealth of Independent States (CIS) is a regional intergovernmental organization in Eurasia. It was formed following the dissolution of the Soviet Union in 1991. It covers an area of and has an estimated population of 239,796,010. The CIS encourages cooperation in economic, political and military affairs and has certain powers relating to the coordination of trade, finance, lawmaking, and security. It has also promoted cooperation on cross-border crime prevention. As the Soviet Union disintegrated, Belarus, Russia and Ukraine signed the Belovezh Accords on 8 December 1991, declaring that the Union had effectively ceased to exist and proclaimed the CIS in its place. On 21 December, the Alma-Ata Protocol was signed. The Baltic states (Estonia, Latvia and Lithuania), which regard their membership in the Soviet Union as an illegal occupation, chose not to participate. Georgia withdrew its membership in 2008 following the Russo-Georgian War. Ukraine formally ended its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zimmerwald
Zimmerwald was an independent municipality in the Canton of Bern, Switzerland until 31 December 2003. It is located on a hill in the proximity of the city of Bern in the Bernese Mittelland. On 1 January 2004 Zimmerwald united with the municipality of Englisberg to form the new municipality of Wald. On 31 December 2002 the population was 870. The coat of arms is three fir trees on three green mountain peaks with a background that ranges from silver to green. History Zimmerwald was only settled in the late phase of the Germanic colonisation of Switzerland. Between 800 and 900, Ciberni entering Southern Germany first settled on the ''Längenberg'' (Long Mountain), the hill on which Zimmerwald lies. The town is first mentioned in documents in the later Middle Ages. In 1999, Zimmerwald celebrated its 700th anniversary. Zimmerwald is remembered in world history for the Zimmerwald Conference held in September 1915. Prominent socialists met from across Europe, among them Leon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geodetic Observatory Wettzell
The Geodetic Observatory Wettzell is located atop the 616 meter-high mountain Wagnerberg, west of the village Wettzell in the German district Cham in the Bavarian Forest. Tasks It is operated for the purpose of geodesy by the Federal Agency for Cartography and Geodesy together with the Technical University of Munich and is today one of the most important geodetic observatories in the world. As observing station, the Geodetic Observatory Wettzell has the task of gathering measuring data for the geodetic space techniques VLBI, SLR, GNSS and DORIS. These data are used for realizing global coordinate reference systems that form the basis for numerous issues in the field of geosciences (e.g. continental drift, sea level rise), in aerospace, but also in areas of everyday life (e.g. surveying, navigation). These global tasks can today only be solved through international cooperation. The activities like observations, data flow, data analysis and provision of results are coordina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Telescope
A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night. Since astronomical radio sources such as planets, stars, nebulas and galaxies are very far away, the radio waves coming from them are extremely weak, so radio telescopes require very large antennas to collect enough radio energy to study them, and extremely sensitive receiving equipment. Radio telescopes are typically large parabolic ("dish") antennas similar to those employed in tracking an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onsala Space Observatory
Onsala Space Observatory (OSO), the Swedish National Facility for Radio Astronomy, provides scientists with equipment to study the Earth and the rest of the Universe. The observatory operates two radio telescopes in Onsala, 45 km south of Gothenburg, and takes part in several international projects. Examples of activities: * The 20 and 25 m telescopes in Onsala: Studies of the birth and death of stars, and of molecules in the Milky Way and other galaxies. * LOFAR station: The Swedish station in the international radio telescope LOFAR is located at the observatory. * VLBI: Telescopes in different countries are linked together for better resolution ("sharper images"). * ALMA, e-VLBI, Herschel Space Observatory, SKA: Developing and using new radio astronomical facilities. * APEX: Radio telescope in Chile for sub-millimetre waves. Research about everything from planets to the structure of the Universe. * Odin: Satellite for studies of, e.g., the Earth's atmosphere and molecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malvern, Worcestershire
Malvern is a spa town and civil parish in Worcestershire, England. It lies at the foot of the Malvern Hills, a designated Area of Outstanding Natural Beauty. The centre of Malvern, Great Malvern, is a historic conservation area, which grew dramatically in Victorian times due to the natural mineral water springs in the vicinity, including Malvern Water. At the 2011 census it had a population of 29,626. It includes Great Malvern on the steep eastern flank of the Malvern Hills, as well as the former independent urban district of Malvern Link. Many of the major suburbs and settlements that comprise the town are separated by large tracts of open common land and fields, and together with smaller civil parishes adjoining the town's boundaries and the hills, the built up area is often referred to collectively as The Malverns. Archaeological evidence suggests that Bronze Age people had settled in the area around 1000 BC, although it is not known whether these settlements were permane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
