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Azimuths And Bearings
An azimuth (; from ar, اَلسُّمُوت, as-sumūt, the directions) is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north. Mathematically, the relative position vector from an observer (origin) to a point of interest is projected perpendicularly onto a reference plane (the horizontal plane); the angle between the projected vector and a reference vector on the reference plane is called the azimuth. When used as a celestial coordinate, the azimuth is the horizontal direction of a star or other astronomical object in the sky. The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5 km radius at sea level) around an observer on Earth's surface, and the reference vector points to true north. The azimuth is the angle between the north vector and the star's vector on the horizontal plane. Azimuth is usually measured in degrees ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Surface
A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets (including Earth), dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs). The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus of a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land (or ground) is the term given to non-liquid planetary surfaces. The term '' landing'' is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached. In differentiated bodies, the surface is where the crust meets the planetary boundary layer. Anything below this is regarded as being sub-surface or sub-ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celestial Navigation
Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space (or on the surface of the Earth) without having to rely solely on estimated positional calculations, commonly known as " dead reckoning", made in the absence of satellite navigation or other similar modern electronic or digital positioning means. Celestial navigation uses "sights", or timed angular measurements, taken typically between a celestial body (e.g. the Sun, the Moon, a planet, or a star) and the visible horizon. Celestial navigation can also take advantage of measurements between celestial bodies without reference to the Earth horizon, such as when the Moon and other selected bodies are used in the practice called "lunars" or lunar distance method, used for determining precise time when time is unknown. Celestial navigation by taking sights of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sun And Moon Letters
In Arabic and Maltese, the consonants are divided into two groups, called the sun letters or solar letters ( ar, حروف شمسية ', mt, konsonanti xemxin) and moon letters or lunar letters (Arabic: ', mt, konsonanti qamrin), based on whether they assimilate the letter ' ( ') of a preceding Arabic definite article ''al-'' (), which is an important general rule used in Arabic grammar. Phonetically, sun letters are ones pronounced as coronal consonants, and moon letters are ones pronounced as other consonants. These names come from the fact that the word for 'the sun', ', pronounced ''ash-shams'', assimilates the ', while the word for 'the moon', ', doesn't. This also applies to the Maltese language where they are written as ''ix-xemx'' and ''il-qamar''. Rule When followed by a sun letter, the of the Arabic definite article assimilates to the initial consonant of the following noun, resulting in a doubled consonant. For example, "the Nile" is pronounced , not . Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
King Alfonso X
Alfonso X (also known as the Wise, es, el Sabio; 23 November 1221 – 4 April 1284) was King of Castile, León and Galicia from 30 May 1252 until his death in 1284. During the election of 1257, a dissident faction chose him to be king of Germany on 1 April. He renounced his claim to Germany in 1275, and in creating an alliance with the Kingdom of England in 1254, his claim on the Duchy of Gascony as well. Alfonso X fostered the development of a cosmopolitan court that encouraged learning. Jews, Muslims, and Christians were encouraged to have prominent roles in his court. As a result of his encouraging the translation of works from Arabic and Latin into the vernacular of Castile, many intellectual changes took place, including the encouragement of the use of Castilian as a primary language of higher learning, science, and law. Alfonso was a prolific author of Galician poetry, such as the ''Cantigas de Santa Maria'', which are equally notable for their musical content as for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libros Del Saber De Astronomía
The , ( osp, Libro del saber de astrología), "Books of wisdom of astronomy/astrology of King Alfonso X of Castile", is a series of books of the medieval period, composed during the reign of Alfonso X of Castile. They describe the celestial bodies and the astronomical instruments existing at the time. The collection is a group of treatises on astronomical instruments, like the celestial sphere, the spherical and plane astrolabe, saphea, and universal plate for all latitudes, for uranography or star cartography that can be used for casting horoscopes. The purpose of the rest of the instruments, the quadrant of the type called vetus, sundial, clepsydras, is to determine the time, which was also needed to cast the horoscope. The king looked for separate works for the construction and use of each device. Of the three scientific collections that Alfonso X commissioned between 1276 and 1279, this is the only one that survived with the full original text intact. It is a group of technical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Treatise On The Astrolabe
''A Treatise on the Astrolabe'' is a medieval instruction manual on the astrolabe by Geoffrey Chaucer. It describes both the form and the proper use of the instrument, and stands out as a prose technical work from a writer better known for poetry, written in English rather than the more typical Latin. Significance The ''Treatise'' is considered the "oldest work in English written upon an elaborate scientific instrument". It is admired for its clarity in explaining difficult concepts – although modern readers lacking an actual astrolabe may find the details of the astrolabe difficult to understand. Robinson believes that it indicates that had Chaucer written more freely composed prose it would have been superior to his translations of Boethius and Renaut de Louhans. Chaucer’s exact source is undetermined but most of his ‘conclusions’ go back, directly or indirectly, to ''Compositio et Operatio Astrolabii'', a Latin translation of Messahala's Arabic treatise of the 8 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geoffrey Chaucer
Geoffrey Chaucer (; – 25 October 1400) was an English poet, author, and civil servant best known for '' The Canterbury Tales''. He has been called the "father of English literature", or, alternatively, the "father of English poetry". He was the first writer to be buried in what has since come to be called Poets' Corner, in Westminster Abbey. Chaucer also gained fame as a philosopher and astronomer, composing the scientific '' A Treatise on the Astrolabe'' for his 10-year-old son Lewis. He maintained a career in the civil service as a bureaucrat, courtier, diplomat, and member of parliament. Among Chaucer's many other works are '' The Book of the Duchess'', '' The House of Fame'', '' The Legend of Good Women'', and '' Troilus and Criseyde''. He is seen as crucial in legitimising the literary use of Middle English when the dominant literary languages in England were still Anglo-Norman French and Latin. Chaucer's contemporary Thomas Hoccleve hailed him as "the firste fyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrolabe
An astrolabe ( grc, ἀστρολάβος ; ar, ٱلأَسْطُرلاب ; persian, ستارهیاب ) is an ancient astronomical instrument that was a handheld model of the universe. Its various functions also make it an elaborate inclinometer and an analog calculation device capable of working out several kinds of problems in astronomy. In its simplest form it is a metal disc with a pattern of wires, cutouts, and perforations that allows a user to calculate astronomical positions precisely. Historically used by astronomers, it is able to measure the altitude above the horizon of a celestial body, day or night; it can be used to identify stars or planets, to determine local latitude given local time (and vice versa), to survey, or to triangulate. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes. The astrolabe's importance comes not only from the early developments into the study of astron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ballistics
Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially ranged weapon munitions such as bullets, unguided bombs, rockets or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance. A ballistic body is a free-moving body with momentum which can be subject to forces such as the forces exerted by pressurized gases from a gun barrel or a propelling nozzle, normal force by rifling, and gravity and air drag during flight. A ballistic missile is a missile that is guided only during the relatively brief initial phase of powered flight and the trajectory is subsequently governed by the laws of classical mechanics; in contrast to (for example) a cruise missile which is aerodynamically guided in powered flight like a fixed-wing aircraft. History and prehistory The earliest known ballistic projectiles were stones and spears, and the throwing stick. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering
Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more specialized fields of engineering, each with a more specific emphasis on particular areas of applied mathematics, applied science, and types of application. See glossary of engineering. The term ''engineering'' is derived from the Latin ''ingenium'', meaning "cleverness" and ''ingeniare'', meaning "to contrive, devise". Definition The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET) has defined "engineering" as: The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. This can be dated back to Hipparchus, who around 190 BC used the catalogue of his predecessors Timocharis and Aristillus to discover Earth's precession. In doing so, he also developed the brightness scale still in use today. Hipparchus compiled a catalogue with at least 850 stars and their positions. Hipparchus's successor, Ptolemy, included a catalogue of 1,022 stars in his work the ''Almagest'', giving their location, coordinates, and brightness. In the 10th century, Abd al-Rahman al-Sufi carried out observations on the stars and described their positions, magn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
