Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics and chemistry in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, stars, nebulae and comets. More all phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject is physical cosmology, the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences; the early civilizations in recorded history, such as the Babylonians, Indians, Nubians, Chinese and many ancient indigenous peoples of the Americas, performed methodical observations of the night sky. Astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, but professional astronomy is now considered to be synonymous with astrophysics. Professional astronomy is split into theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, analyzed using basic principles of physics.
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain observational results and observations being used to confirm theoretical results. Astronomy is one of the few sciences in which amateurs still play an active role in the discovery and observation of transient events. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets. Astronomy means "law of the stars". Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now distinct. Both of the terms "astronomy" and "astrophysics" may be used to refer to the same subject. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties," while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, dynamic processes of celestial objects and phenomena."
In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could be called astrophysics; some fields, such as astrometry, are purely astronomy rather than astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics" depending on whether the department is affiliated with a physics department, many professional astronomers have physics rather than astronomy degrees; some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, Astronomy and Astrophysics. In early historic times, astronomy only consisted of the observation and predictions of the motions of objects visible to the naked eye.
In some locations, early cultures assembled massive artifacts that had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye; as civilizations developed, most notably in Mesopotamia, Persia, China and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, the nature of the Sun and the Earth in the Universe were explored philosophically; the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Ptolemaic system, named after Ptolemy.
A important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the astronomical traditions that developed in many other civilizations. The Babylonians discovered. Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, he proposed a model of the Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and inven
A meridian is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator; each meridian is perpendicular to all circles of latitude. Each is the same length, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km. The first prime meridian was set by Eratosthenes in 200 BCE; this prime meridian was used to provide measurement of the earth, but had many problems because of the lack of latitude measurement. Many years around the 19th century there was still concerns of the prime meridian; the idea of having one prime meridian came from William Parker Snow, because he realized the confusion of having multiple prime meridian locations. Many of theses geographical locations were traced back to the ancient Greeks, others were created by several nations.
Multiple locations for the geographical meridian meant that there was inconsistency, because each country had their own guidelines for where the prime meridian was located. The term meridian comes from the spanish meridies, meaning "midday"; the Sun crosses the celestial meridian at the same time. The same Latin stem gives rise to the terms a.m. and p.m. used to disambiguate hours of the day when utilizing the 12-hour clock. Toward the ending of the 12th century there were two main locations that were acknowledged as the geographic location of the meridian and Britain; these two locations conflicted and a settlement was reached only after there was an International Meridian Conference held, in which Greenwich was recognized as the 0° location. The meridian through Greenwich, called the Prime Meridian, was set at zero degrees of longitude, while other meridians were defined by the angle at the center of the earth between where it and the prime meridian cross the equator; as there are 360 degrees in a circle, the meridian on the opposite side of the earth from Greenwich, the antimeridian, forms the other half of a circle with the one through Greenwich, is at 180° longitude near the International Date Line.
The meridians from West of Greenwich to the antimeridian define the Western Hemisphere and the meridians from East of Greenwich to the antimeridian define the Eastern Hemisphere. Most maps show the lines of longitude; the position of the prime meridian has changed a few times throughout history due to the transit observatory being built next door to the previous one. Such changes had no significant practical effect; the average error in the determination of longitude was much larger than the change in position. The adoption of WGS84 as the positioning system has moved the geodetic prime meridian 102.478 metres east of its last astronomic position. The position of the current geodetic prime meridian is not identified at all by any kind of sign or marking in Greenwich, but can be located using a GPS receiver, it was in the best interests of the nations to agree to one standard meridian to benefit their fast growing economy and production. The disorganized system they had before was not sufficient for their increasing mobility.
The coach services in England had erratic timing before the GWT. U. S. and Canada were improving their railroad system and needed a standard time as well. With a standard meridian, stage coach and trains were able to be more efficient; the argument of which meridian is more scientific was set aside in order to find the most convenient for practical reasons. They were able to agree that the universal day was going to be the mean solar day, they agreed that the days would begin at midnight and the universal day would not impact the use of local time. In the "Transactions of the Royal Society of Canada a report was submitted, dated 10 May 1894. Therefore, a compass needle will be parallel to the magnetic meridian. However, a compass needle will not be steady in the magnetic meridian, because of the longitude from east to west being complete geodesic; the angle between the magnetic and the true meridian is the magnetic declination, relevant for navigating with a compass. Navigators were able to use the azimuth of the rising and setting Sun to measure the magnetic variation.
The true meridian is the plane that passes through true north poles and true south poles at the spot of the observer. The difference between true meridian and magnetic meridian is that the true meridian is fixed while the magnetic meridian is formed through the movement of the needle. True bearing is the horizontal angle between a line. Henry D. Thoreau classified this true meridian
Mechanics is that area of science concerned with the behaviour of physical bodies when subjected to forces or displacements, the subsequent effects of the bodies on their environment. The scientific discipline has its origins in Ancient Greece with the writings of Aristotle and Archimedes. During the early modern period, scientists such as Galileo and Newton laid the foundation for what is now known as classical mechanics, it is a branch of classical physics that deals with particles that are either at rest or are moving with velocities less than the speed of light. It can be defined as a branch of science which deals with the motion of and forces on objects; the field is yet less understood in terms of quantum theory. Classical mechanics came first and quantum mechanics is a comparatively recent development. Classical mechanics originated with Isaac Newton's laws of motion in Philosophiæ Naturalis Principia Mathematica. Both are held to constitute the most certain knowledge that exists about physical nature.
Classical mechanics has often been viewed as a model for other so-called exact sciences. Essential in this respect is the extensive use of mathematics in theories, as well as the decisive role played by experiment in generating and testing them. Quantum mechanics is of a bigger scope, as it encompasses classical mechanics as a sub-discipline which applies under certain restricted circumstances. According to the correspondence principle, there is no contradiction or conflict between the two subjects, each pertains to specific situations; the correspondence principle states that the behavior of systems described by quantum theories reproduces classical physics in the limit of large quantum numbers. Quantum mechanics has superseded classical mechanics at the foundation level and is indispensable for the explanation and prediction of processes at the molecular and sub-atomic level. However, for macroscopic processes classical mechanics is able to solve problems which are unmanageably difficult in quantum mechanics and hence remains useful and well used.
Modern descriptions of such behavior begin with a careful definition of such quantities as displacement, velocity, acceleration and force. Until about 400 years ago, motion was explained from a different point of view. For example, following the ideas of Greek philosopher and scientist Aristotle, scientists reasoned that a cannonball falls down because its natural position is in the Earth. Cited as father to modern science, Galileo brought together the ideas of other great thinkers of his time and began to calculate motion in terms of distance traveled from some starting position and the time that it took, he showed that the speed of falling objects increases during the time of their fall. This acceleration is the same for heavy objects as for light ones, provided air friction is discounted; the English mathematician and physicist Isaac Newton improved this analysis by defining force and mass and relating these to acceleration. For objects traveling at speeds close to the speed of light, Newton's laws were superseded by Albert Einstein’s theory of relativity.
For atomic and subatomic particles, Newton's laws were superseded by quantum theory. For everyday phenomena, Newton's three laws of motion remain the cornerstone of dynamics, the study of what causes motion. In analogy to the distinction between quantum and classical mechanics, Einstein's general and special theories of relativity have expanded the scope of Newton and Galileo's formulation of mechanics; the differences between relativistic and Newtonian mechanics become significant and dominant as the velocity of a massive body approaches the speed of light. For instance, in Newtonian mechanics, Newton's laws of motion specify that F = ma, whereas in relativistic mechanics and Lorentz transformations, which were first discovered by Hendrik Lorentz, F = γma. Relativistic corrections are needed for quantum mechanics, although general relativity has not been integrated; the two theories remain incompatible, a hurdle which must be overcome in developing a theory of everything. The main theory of mechanics in antiquity was Aristotelian mechanics.
A developer in this tradition is Hipparchus. In the Middle Ages, Aristotle's theories were criticized and modified by a number of figures, beginning with John Philoponus in the 6th century. A central problem was that of projectile motion, discussed by Hipparchus and Philoponus. Persian Islamic polymath Ibn Sīnā published his theory of motion in The Book of Healing, he said that an impetus is imparted to a projectile by the thrower, viewed it as persistent, requiring external forces such as air resistance to dissipate it. Ibn Sina made distinction between'force' and'inclination', argued that an object gained mayl when the object is in opposition to its natural motion. So he concluded that continuation of motion is attributed to the inclination, transferred to the object, that object will be in motion until the mayl is spent, he claimed that projectile in a vacuum would not stop unless it is acted upon. This conception of motion is consistent with Newton's first law of inertia. Which states that an object in motion will stay in mo
Virtual International Authority File
The Virtual International Authority File is an international authority file. It is a joint project of several national libraries and operated by the Online Computer Library Center. Discussion about having a common international authority started in the late 1990s. After a series of failed attempts to come up with a unique common authority file, the new idea was to link existing national authorities; this would present all the benefits of a common file without requiring a large investment of time and expense in the process. The project was initiated by the US Library of Congress, the German National Library and the OCLC on August 6, 2003; the Bibliothèque nationale de France joined the project on October 5, 2007. The project transitioned to being a service of the OCLC on April 4, 2012; the aim is to link the national authority files to a single virtual authority file. In this file, identical records from the different data sets are linked together. A VIAF record receives a standard data number, contains the primary "see" and "see also" records from the original records, refers to the original authority records.
The data are available for research and data exchange and sharing. Reciprocal updating uses the Open Archives Initiative Protocol for Metadata Harvesting protocol; the file numbers are being added to Wikipedia biographical articles and are incorporated into Wikidata. VIAF's clustering algorithm is run every month; as more data are added from participating libraries, clusters of authority records may coalesce or split, leading to some fluctuation in the VIAF identifier of certain authority records. Authority control Faceted Application of Subject Terminology Integrated Authority File International Standard Authority Data Number International Standard Name Identifier Wikipedia's authority control template for articles Official website VIAF at OCLC
Système universitaire de documentation
The système universitaire de documentation or SUDOC is a system used by the libraries of French universities and higher education establishments to identify and manage the documents in their possession. The catalog, which contains more than 10 million references, allows students and researcher to search for bibliographical and location information in over 3,400 documentation centers, it is maintained by the Bibliographic Agency for Higher Education. Official website
Budrio is a town and comune in the Metropolitan City of Bologna, in Emilia-Romagna, Italy. Budrio is the birthplace of Giuseppe Barilli, better known under his pseudonym of Quirico Filopanti, an Italian mathematician and politician. Budrio's area was a Roman colony; the current town was however founded in the 10th-11th centuries AD. The church of San Lorenzo was active in 1146. In the 14th century Cardinal Gil de Albornoz rebuilt it as a castle, of which the two large towers can still be seen, while of the walls only a small section remains; the most notable attraction are the Villa Ranuzzi Cospi at Bagnarola. The town houses the Pinacoteca Domenico Inzaghi and the churches of San Domenico del Rosario, San Lorenzo, Santi Gervasio e Protasio. Giuseppe Donati, inventor of the ocarina Quirico Filopanti and politician Gustavo Fiorini, retired footballer Gyula, since 1965 Eichenau, since 1991 Official website Radio Budrio