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Zīj
A ' () is an Islamic astronomical book that tabulates parameters used for astronomical calculations of the positions of the sun, moon, stars, and planets. Etymology The name ''zīj'' is derived from the Middle Persian term ' or ' "cord". The term is believed to refer to the arrangement of threads in weaving, which was transferred to the arrangement of rows and columns in tabulated data. Some such books were referred to as ', derived from the equivalent Greek word, . Historically significant zījes The ''Zij-i Sultani'', published by the astronomer and sultan Ulugh Beg in 1438/9, was used as a reference ' throughout Islam during the early modern era. Omar Khayyam's '' Zij-i Malik Shahi'' was updated throughout the modern era under various sultanates. ' were updated by different empires to suit their various interests, such as the simplified version of ' by the Mughal Empire. History Some of the early ''zīj''es tabulated data from Indian planetary theory (known as the Sin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy In Medieval Islam
Medieval Islamic astronomy comprises the Astronomy, 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 History of India, 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 astronomy, Greek, Sassanid Empire, Sassanid, and Indian astronomy, Indian works in particular, which were translated and built upon. Islamic astronomy played a significant role in the revival of ancient astronomy following the Dark Ages (historiography), loss of knowledge during the early medieval period, notably with the production of Middle Latin, Latin translations of Arabic works La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephemeris
In astronomy and celestial navigation, an ephemeris (; ; , ) is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available. The astronomical position calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination, together with the distance from the origin if applicable. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary es, sidereal time, positions for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zij-i Sultani
''Zīj-i Sulṭānī'' () is a Zij astronomical table and star catalogue that was published by Ulugh Beg in 1438–1439. It was the joint product of the work of a group of Muslim astronomers working under the patronage of Ulugh Beg at Samarkand's Ulugh Beg Observatory. These astronomers included Jamshid al-Kashi and Ali Qushji, among others. The ''Zij-i-Sultani'' was not surpassed in accuracy until the work of Taqi ad-Din and Tycho Brahe in the 16th century. The serious errors which Ulugh Beg found in previous Zij star catalogues (many of the earlier ones were simply updates on Ptolemy's work, adding the effect of precession to the longitudes) induced him to redetermine the positions of 992 fixed stars, to which he added 27 stars from al-Sufi's ''Book of Fixed Stars'' (964), which were too far south for observation from Samarkand. This catalogue, one of the most original of the Middle Ages, was edited by Thomas Hyde at Oxford in 1665 under the title ''Jadāvil-i Mavāzi' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Islamic Astrology
Astrology refers to the study of the movements and relative positions of celestial bodies interpreted as having an influence on human affairs and the natural world. In early Islamic history, astrology (''ʿilm al-nujūm'', ), was "by far" the most popular of the "numerous practices attempting to foretell future events or discern hidden things", according to historian Emilie Savage-Smith.#ESMaDiEI2004, Savage-Smith, ''Magic and Divination in Early Islam'', 2004: p.xxxvii Some medieval Muslims took an interest in the study of the apparent motion of the stars. This was partly because they considered the celestial bodies to be essential, and partly because the dwellers of desert-regions often traveled at night, and relied upon knowledge of the constellations for guidance in their journeys. After the arrival of Islam, Muslims needed to determine the time of the prayers, which direction the kaaba would face, and the correct orientation of the mosque, all of which helped give a religious ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Moon
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse. The original meaning of the term 'new moon', which is still sometimes used in calendrical, non-astronomical contexts, is the first visible crescent of the Moon after conjunction with the Sun. This thin waxing crescent is briefly and faintly visible as the Moon gets lower in the western sky after sunset. The precise time and even the date of the appearance of the new moon by this definition will be influenced by the geographical location of the observer. The first crescent marks the beginning of the month in the Islamic calendar and in some lunisolar calendars such as the Hebrew calendar. In the Chinese calendar, the beginning of the month is marked by the last visible crescent of a waning Moon. The astronomical new moon occurs by def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eclipses
An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three celestial objects is known as a ''syzygy''. An eclipse is the result of either an ''occultation'' (completely hidden) or a ''transit'' (partially hidden). A "deep eclipse" (or "deep occultation") is when a small astronomical object is behind a bigger one. "What is a deep eclipse? The smaller star is behind the bigger star" The term ''eclipse'' is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equation Of Time
The equation of time describes the discrepancy between two kinds of solar time. The two times that differ are the apparent solar time, which directly tracks the diurnal motion of the Sun, and mean solar time, which tracks a theoretical mean Sun with uniform motion along the celestial equator. Apparent solar time can be obtained by measurement of the current position (Hour angle#Solar hour angle, hour angle) of the Sun, as indicated (with limited accuracy) by a sundial. ''Mean'' solar time, for the same place, would be the time indicated by a steady clock set so that over the year its differences from apparent solar time would have a mean of zero. The equation of time is the east or west component of the analemma, a curve representing the angular offset of the Sun from its mean position on the celestial sphere as viewed from Earth. The equation of time values for each day of the year, compiled by astronomical observatory, observatories, were widely listed in almanacs and ephemeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Astronomy
Spherical astronomy, or positional astronomy, is a branch of observational astronomy used to locate astronomical objects on the celestial sphere, as seen at a particular date, time, and location on Earth. It relies on the mathematical methods of spherical trigonometry and the measurements of astrometry. This is the oldest branch of astronomy and dates back to antiquity. Observations of celestial objects have been, and continue to be, important for religious and astrological purposes, as well as for timekeeping and navigation. The science of actually measuring positions of celestial objects in the sky is known as astrometry. The primary elements of spherical astronomy are celestial coordinate systems and time. The coordinates of objects on the sky are listed using the equatorial coordinate system, which is based on the projection of Earth's equator onto the celestial sphere. The position of an object in this system is given in terms of right ascension (α) and declination (δ). ... [...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] |
Star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night; their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and traces of heavier elements. Its stellar mass, total mass mainly determines it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude
Longitude (, ) is a geographic coordinate that specifies the east- west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians are imaginary semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, south-east London on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west. Because of the Earth's rotation, there is a close connection between longitude and time measurement. Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latitude
In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Parallel (latitude), Lines of constant latitude, or ''parallels'', run east-west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth. On its own, the term "latitude" normally refers to the ''geodetic latitude'' as defined below. Briefly, the geodetic latitude of a point is the angle formed between the vector perpendicular (or ''Normal (geometry), normal'') to the ellipsoidal surface from the point, and the equatorial plane, plane of the equator. Background Two levels of abstraction are employed in the definitions of latitude and longitude. In the first step the physical surface i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
