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Chalid Ben Abdulmelik
Khālid ibn ʿAbd al‐Malik al‐Marwarrūdhī ( ar, خالد بن عبدالملك المرو الروذي) was a 9th-century Baghdadi astronomer. In 827, Marwarrūdhī, together with the astronomer ʿAlī ibn ʿĪsā al-Asṭurlābī and a party of surveyors, measured the length of a meridian arc of one degree of latitude. The party travelled to the Nineveh Plains in the valley of the Tigris, at 35 degrees north latitude. The measurement they obtained enabled the astronomers to obtain a value of for the circumference of the Earth, (or, according to other sources, ). The two researchers measured in Arabian , and determined the geographical latitudes of the end points they used from the star altitudes in a celestial horizontal coordinate system. As it is thought that one Arabian represented , they found the length of 1° of meridian to be , which differs from the true value by . Marwarrūdhī was chosen by the geometer Al-Abbās ibn Said al-Jawharī to organize a new ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Islamic Golden Age
The Islamic Golden Age was a period of cultural, economic, and scientific flourishing in the history of Islam, traditionally dated from the 8th century to the 14th century. This period is traditionally understood to have begun during the reign of the Abbasid caliph Harun al-Rashid (786 to 809) with the inauguration of the House of Wisdom in Baghdad, the world's largest city by then, where Muslim scholars and polymaths from various parts of the world with different cultural backgrounds were mandated to gather and translate all of the known world's classical knowledge into Aramaic and Arabic. The period is traditionally said to have ended with the collapse of the Abbasid caliphate due to Mongol invasions and the Siege of Baghdad in 1258. A few scholars date the end of the golden age around 1350 linking with the Timurid Renaissance, while several modern historians and scholars place the end of the Islamic Golden Age as late as the end of 15th to 16th centuries meeting with the I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumference
In geometry, the circumference (from Latin ''circumferens'', meaning "carrying around") is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out to a line segment. More generally, the perimeter is the curve length around any closed figure. Circumference may also refer to the circle itself, that is, the locus corresponding to the edge of a disk. The is the circumference, or length, of any one of its great circles. Circle The circumference of a circle is the distance around it, but if, as in many elementary treatments, distance is defined in terms of straight lines, this cannot be used as a definition. Under these circumstances, the circumference of a circle may be defined as the limit of the perimeters of inscribed regular polygons as the number of sides increases without bound. The term circumference is used when measuring physical objects, as well as when considering abstract g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geodesists
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivalent measurements for other planets (known as ''planetary geodesy''). Geodynamical phenomena, including crustal motion, tides and polar motion, can be studied by designing global and national control networks, applying space geodesy and terrestrial geodetic techniques and relying on datums and coordinate systems. The job title is geodesist or geodetic surveyor. History Definition The word geodesy comes from the Ancient Greek word ''geodaisia'' (literally, "division of Earth"). It is primarily concerned with positioning within the temporally varying gravitational field. Geodesy in the German-speaking world is divided into "higher geodesy" ( or ), which is concerned with measuring Earth on the global scale, and "practical geodesy" o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It has 193 member states and 12 associate members, as well as partners in the non-governmental, intergovernmental and private sector. Headquartered at the World Heritage Centre in Paris, France, UNESCO has 53 regional field offices and 199 national commissions that facilitate its global mandate. UNESCO was founded in 1945 as the successor to the League of Nations's International Committee on Intellectual Cooperation.English summary). Its constitution establishes the agency's goals, governing structure, and operating framework. UNESCO's founding mission, which was shaped by the Second World War, is to advance peace, sustainable development and human rights by facilitating collaboration and dialogue among nations. It pursues this objective t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Qasioun
Mount Qasioun ( ar, جَبَل قَاسِيُون, transliterated as Jabal Qāsiyūn) is a mountain overlooking the city of Damascus, Syria. It has a range of restaurants, from which the whole city can be viewed. As the city has expanded over the years, some districts have been established on the foot of the mountain. Its highest point is . The mountain has been heavily entrenched with Syrian government forces since the start of the Syrian Civil War, as it is a strategic site in the battle for the outskirts of Damascus. The mountain is also host to an endemic species of iris, '' Iris damascena'', which can be found on the steep eastern slopes, at an altitude of above sea level. The Syrian government has not given the species any protected status. Its only benefiting factor was that part of the habitat of the species lies within a military area near the 'Qassioun Republican Guards Military Base' and other military facilities, which prevents civilians from accessing the area. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observatory
An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. Historically, observatories were as simple as containing an astronomical sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena). Astronomical observatories Astronomical observatories are mainly divided into four categories: space-based, airborne, ground-based, and underground-based. Ground-based observatories 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al-Abbās Ibn Said Al-Jawharī
(c. 800 Baghdad? – c. 860 Baghdad?) was a geometer who worked at the House of Wisdom in Baghdad and for in a short time in Damascus where he made astronomical observations. He was probably of Iranian origin. His most important work was his ''Commentary on Euclid's Elements'' which contained nearly 50 additional propositions and an attempted proof of the parallel postulate. Described as having superb knowledge of Greek (quite unusual for a Muslim scholar), he is also credited with a translation of Shanaq al-Hindi's ''Book of Poisons'' from Pehlevi into Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ..., ''Kitab al-Sumum''. References * * * * External links * PDF version * * 800s births 860 deaths People from Baghdad 9th-century Iranian mathem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geometer
A geometer is a mathematician whose area of study is geometry. Some notable geometers and their main fields of work, chronologically listed, are: 1000 BCE to 1 BCE * Baudhayana (fl. c. 800 BC) – Euclidean geometry, geometric algebra * Manava (c. 750 BC–690 BC) – Euclidean geometry * Thales of Miletus (c. 624 BC – c. 546 BC) – Euclidean geometry * Pythagoras (c. 570 BC – c. 495 BC) – Euclidean geometry, Pythagorean theorem * Zeno of Elea (c. 490 BC – c. 430 BC) – Euclidean geometry * Hippocrates of Chios (born c. 470 – 410 BC) – first systematically organized '' Stoicheia – Elements'' (geometry textbook) * Mozi (c. 468 BC – c. 391 BC) * Plato (427–347 BC) * Theaetetus (c. 417 BC – 369 BC) * Autolycus of Pitane (360–c. 290 BC) – astronomy, spherical geometry * Euclid (fl. 300 BC) – '' Elements'', Euclidean geometry (sometimes called the "father of geometry") * Apollonius of Perga (c. 262 BC – c. 190 BC) – Euclidean geometry, conic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Coordinate System
The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles: altitude and azimuth. Therefore, the horizontal coordinate system is sometimes called as the az/el system, the alt/az system, or the alt-azimuth system, among others. In an altazimuth mount of a telescope, the instrument's two axes follow altitude and azimuth. Definition This celestial coordinate system divides the sky into two hemispheres: The upper hemisphere, where objects are above the horizon and are visible, and the lower hemisphere, where objects are below the horizon and cannot be seen, since the Earth obstructs views of them. The great circle separating the hemispheres is called the celestial horizon, which is defined as the great circle on the celestial sphere whose plane is normal to the local gravity vector. In practice, the horizon can be defined as the plane tangent to a quiet, liquid surface, such as a pool of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altitude
Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical survey, sport, or atmospheric pressure). Although the term ''altitude'' is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage. Vertical distance measurements in the "down" direction are commonly referred to as depth. In aviation In aviation, the term altitude can have several meanings, and is always qualified by explicitly adding a modifier (e.g. "true altitude"), or implicitly through the context of the communication. Parties exchanging altitude information must be clear which definition is being used. Aviation altitude is measured using either mean sea level (MSL) or local ground level (above ground level, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
35th Parallel North
The 35th parallel north is a circle of latitude that is 35 degrees north of the Earth's equatorial plane. It crosses Africa, the Mediterranean Sea, Asia, the Pacific Ocean, North America and the Atlantic Ocean. In the United States, the parallel defines the southern border of Tennessee, and the border between North Carolina and Georgia, as well as the tripoint of Arizona–California–Nevada. At this northern latitude, the Sun is visible for 14 hours, 31 minutes on its summer solstice (in June) and for 9 hours, 48 minutes on its winter solstice (in December). This parallel is sometimes used to define the northern boundary of the subtropics. Around the world Starting at the Prime Meridian and heading eastwards, the parallel 35° north passes through: : See also * 34th parallel north The 34th parallel north is a circle of latitude that is 34 degrees north of the Earth's equatorial plane. It crosses Africa, the Mediterranean Sea, Asia, the Pacific Ocean, North America and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest include planets, natural satellite, moons, stars, nebulae, galaxy, galaxies, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond atmosphere of Earth, Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonian astronomy, Babylonians, Greek astronomy, Greeks, Indian astronomy, Indians, Egyptian astronomy, Egyptians, Chinese astronomy, Chinese, Maya civilization, Maya, and many anc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
