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Habash Al-Hasib Al-Marwazi
Ahmad ibn 'Abdallah al-Marwazi, known as Habash al-Hasib (, died 869) was a Persian astronomer, geographer, and mathematician from Merv in Khorasan, who discovered the trigonometric ratios tangent, and cotangent. Al-Biruni who cited Habash in his work, expanded his astronomical tables. Habash al-Hasib flourished in Baghdad, and died a centenarian some time between 864 and 874 possibly in Abbasid Samarra. The title "Habash" (Abbyssian) may refer to dark skin color. He worked under two Abbasid caliphs, al-Ma'mun and al-Mu'tasim. Habash al-Hasib developed a trigonometric algorithm to solve problems related to parallax, which was later rediscovered by Johannes Kepler in 1609 and it is now known as Kepler's equation. Habash is the father of the astronomer Abu Ja'far ibn Habash. Work Habash Hasib made astronomical observations from 825 to 835, and compiled three '' zijes'' (astronomical tables): the first were still in the Hindu manner; the second, called the "tested" tables ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merv
Merv (, ', ; ), also known as the Merve Oasis, was a major Iranian peoples, Iranian city in Central Asia, on the historical Silk Road, near today's Mary, Turkmenistan. Human settlements on the site of Merv existed from the 3rd millennium BC until the 18th century AD. It changed hands repeatedly throughout history. Under the Achaemenid Empire, it was the center of the satrapy of Margiana. It was subsequently ruled by Hellenistic Period, Hellenistic Kings, Parthians, Sasanian Empire, Sasanians, Arabs, Ghaznavids, Seljuk Turks, Seljuqs, Khwarazmian dynasty, Khwarazmians and Timurids, among others. Merv was the capital city of several polity, polities throughout its history. In the beginning of the 9th century, Merv was the seat of the caliph al-Ma'mun and the capital of the entire Abbasid caliphate, Islamic caliphate. It served later as the seat of the Tahirid dynasty, Tahirid governors of Greater Khorasan, Khorasan. In the 11th–12th centuries, Merv was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abbasid Caliphs
The Abbasid caliphs were the holders of the Islamic title of caliph who were members of the Abbasid dynasty, a branch of the Quraysh tribe descended from the uncle of the Islamic prophet Muhammad, Al-Abbas ibn Abd al-Muttalib. The family came to power in the Abbasid Revolution in 748–750, supplanting the Umayyad Caliphate. They were the rulers of the Abbasid Caliphate, as well as the generally recognized ecumenical heads of Islam, until the 10th century, when the Shi'a Fatimid Caliphate (established in 909) and the Caliphate of Córdoba (established in 929) challenged their primacy. The political decline of the Abbasids had begun earlier, during the Anarchy at Samarra (861–870), which accelerated the fragmentation of the Muslim world into autonomous dynasties. The caliphs lost their temporal power in 936–946, first to a series of military strongmen and then to the Shi'a Buyid Emirs that seized control of Baghdad; the Buyids were in turn replaced by the Sunni Seljuk Tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexagesimal
Sexagesimal, also known as base 60, is a numeral system with 60 (number), sixty as its radix, base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form—for measuring time, angles, and geographic coordinate system, geographic coordinates. The number 60, a superior highly composite number, has twelve divisors, namely 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60, of which 2, 3, and 5 are prime numbers. With so many factors, many fractions involving sexagesimal numbers are simplified. For example, one hour can be divided evenly into sections of 30 minutes, 20 minutes, 15 minutes, 12 minutes, 10 minutes, 6 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, and 1 minute. 60 is the smallest number that is divisible by every number from 1 to 6; that is, it is the lowest common multiple of 1, 2, 3, 4, 5, and 6. ''In this article, all sexagesimal digits are represented as decimal numbers, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth Radius
Earth radius (denoted as ''R''🜨 or ''R''E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted ''a'') of about to a minimum (polar radius, denoted ''b'') of nearly . A globally-average value is usually considered to be with a 0.3% variability (±10 km) for the following reasons. The International Union of Geodesy and Geophysics (IUGG) provides three reference values: the ''mean radius'' (''R'') of three radii measured at two equator points and a pole; the ''authalic radius'', which is the radius of a sphere with the same surface area (''R''); and the ''volumetric radius'', which is the radius of a sphere having the same volume as the ellipsoid (''R''). All three values are about . Other ways to define and measure the Earth's radius involve either the spheroid's radius of curvature or the actual topography. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions are also valid for the diameter of a sphere. In more modern usage, the length d of a diameter is also called the diameter. In this sense one speaks of diameter rather than diameter (which refers to the line segment itself), because all diameters of a circle or sphere have the same length, this being twice the radius r. :d = 2r \qquad\text\qquad r = \frac. The word "diameter" is derived from (), "diameter of a circle", from (), "across, through" and (), "measure". It is often abbreviated \text, \text, d, or \varnothing. Constructions With straightedge and compass, a diameter of a given circle can be constructed as the perpendicular bisector of an arbitrary chord. Drawing two diameters in this way can be used to locate the center of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumference
In geometry, the circumference () is the perimeter of a circle or ellipse. The circumference is 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 (geometry), locus corresponding to the Edge (geometry), edge of a Disk (geometry), 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 (mathematics), 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 abstrac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centaurus (journal)
''Centaurus. Journal of the European Society for the History of Science'' is a quarterly peer-reviewed, open-access academic journal''. Centaurus'' publishes high quality academic content on the history of science in the broadest sense, including the history of mathematics, medicine, biomedical sciences, earth sciences, social sciences, humanities and technology, studied from different perspectives, including epistemic, social, cultural, material and technical aspects. It is the official journal of the European Society for the History of Science (ESHS). The journal was established in 1950. In January 2022, Centaurus was relaunched in open-access format by the ESHS and Brepols as ''Centaurus. Journal of the European Society for the History of Science''. Since 2024 the editor-in-chief is Daniele Cozolli ( Pompeu Fabra University, Spain) and the deputy editor is Doubravka Olšáková (Czech Academy of Sciences, Czech Republic). Abstracting and indexing The journal is abstracted and in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al-Shammisiyyah Observatory
Medieval Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and later in the Far East and India. It closely parallels the genesis of other Islamic sciences in its assimilation of foreign material and the amalgamation of the disparate elements of that material to create a science with Islamic characteristics. These included Greek, Sassanid, and Indian works in particular, which were translated and built upon. Islamic astronomy played a significant role in the revival of ancient astronomy following the loss of knowledge during the early medieval period, notably with the production of Latin translations of Arabic works during the 12th century. A significant number of stars in the sky, such as Aldebaran, Altair and Deneb, and astronomical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica
The is a general knowledge, general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. Since 2016, it has been published exclusively as an online encyclopedia, online encyclopaedia. Printed for 244 years, the ''Britannica'' was the longest-running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in Edinburgh, Scotland, in three volumes. The encyclopaedia grew in size; the second edition was 10 volumes, and by its fourth edition (1801–1810), it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent contributors, and the 9th (1875–1889) and Encyclopædia Britannica Eleventh Edition, 11th editions (1911) are landmark encyclopaedias for scholarship and literary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometry
Trigonometry () is a branch of mathematics concerned with relationships between angles and side lengths of triangles. In particular, the trigonometric functions relate the angles of a right triangle with ratios of its side lengths. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine. Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation. Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation. History Sumerian astronomers studied angle me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season in its new moon phase, when the Moon's orbital plane is closest to Ecliptic, the plane of Earth's orbit. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In #Types, partial and annular eclipses, only part of the Sun is obscured. Unlike a lunar eclipse, which may be viewed from anywhere on the night side of Earth, a solar eclipse can only be viewed from a relatively small area of the world. As such, although total solar eclipses occur somewhere on Earth every 18 months on average, they recur at any given place only once every 360 to 410 years. If the Moon were in a perfectly circular orbit and in the same orbital plane as Earth, there would be total solar eclipses once a month, at every new moon. Instead, because the Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Kepler
Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his Kepler's laws of planetary motion, laws of planetary motion, and his books ''Astronomia nova'', ''Harmonice Mundi'', and ''Epitome Astronomiae Copernicanae'', influencing among others Isaac Newton, providing one of the foundations for his theory of Newton's law of universal gravitation, universal gravitation. The variety and impact of his work made Kepler one of the founders and fathers of modern astronomy, the scientific method, Natural science, natural and modern science. He has been described as the "father of science fiction" for his novel ''Somnium (novel), Somnium''. Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Hans Ulrich von Eggenberg, Prince Hans Ulrich von Eggenberg. Lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
