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Ibn Yunis
Abu al-Hasan 'Ali ibn 'Abd al-Rahman ibn Ahmad ibn Yunus al-Sadafi al-Misri (Arabic: ابن يونس; c. 950 – 1009) was an important Egyptians, Egyptian astronomer and Islamic mathematics, mathematician, whose works are noted for being ahead of their time, having been based on meticulous calculations and attention to detail. The crater Ibn Yunus (crater), Ibn Yunus on the Moon is named after him. Life Information regarding his early life and education is uncertain. He was born in Egypt between 950 and 952 and came from a respected family in Fostat, Fustat. His father was a historian, biographer, and scholar of hadith, who wrote two volumes about the history of Egypt—one about the Egyptians and one based on traveller commentary on Egypt. A prolific writer, Ibn Yunus' father has been described as "Egypt's most celebrated early historian and first known compiler of a biographical dictionary devoted exclusively to Egyptians". His great-grandfather had been an associate of the no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heliacal Rising
The heliacal rising ( ) or star rise of a star occurs annually, or the similar phenomenon of a planet, when it first becomes visible above the eastern horizon at dawn just before sunrise (thus becoming "the morning star") after a complete orbit of the earth around the sun. Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar and astronomical development. The rising of the Pleiades heralded the start of the Ancient Greek sailing season, using celestial navigation. Cause and significance Relative to the stars, the sun appears to drift eastward about one degree per day along a path called the ecliptic because there are 360 degrees in any complete revolution (circle), which takes about 365 days in the case of one revolution of the earth around the sun. Any given "distant" star in the belt of the ecliptic will be visible at night for only half of the year, when it will always remain below the horizon. During the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simon Newcomb
Simon Newcomb (March 12, 1835 – July 11, 1909) was a Canadian–American astronomer, applied mathematician, and autodidactic polymath. He served as Professor of Mathematics in the United States Navy and at Johns Hopkins University. Born in Nova Scotia, at the age of 19 Newcomb left an apprenticeship to join his father in Massachusetts, where the latter was teaching. Though Newcomb had little conventional schooling, he completed a BSc at Harvard in 1858. He later made important contributions to timekeeping, as well as to other fields in applied mathematics, such as economics and statistics. Fluent in several languages, he also wrote and published several popular science books and a science fiction novel. Biography Early life Simon Newcomb was born in the town of Wallace, Nova Scotia. His parents were John Burton Newcomb and his wife Miriam Steeves. His father was an itinerant school teacher, and frequently moved in order to teach in different parts of Canada, particularly in N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Dunthorne
Richard Dunthorne (1711 – 3 March 1775) was an English astronomer and surveyor, who worked in Cambridge as astronomical and scientific assistant to Roger Long (master of Pembroke Hall and Lowndean Professor of Astronomy and Geometry), Library of St John's College, Cambridge, 2008; and Philosophical Transactions (Abridgement Series) (1809). and also concurrently for many years as surveyor to the Bedford Level Corporation. Life and work There are short biographical notes of Dunthorne, one in the Philosophical Transactions (Abridgement Series, published 1809) (unsigned), Philosophical Transactions (Abridgement Series) (1809). another in the 'Dictionary of National Biography' (vol.16), and a third by W T Lynn. Dunthorne was born in humble circumstances in Ramsey, Cambridgeshire, where he attended the free grammar school. There he attracted the notice of Roger Long (later Master of Pembroke Hall, Cambridge), whose protégé Dunthorne became. Dunthorne moved to Cambridge where Lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eclipse
An eclipse is an astronomical event that 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. Apart from syzygy, the term eclipse is also used when a spacecraft reaches a position where it can observe two celestial bodies so aligned. An eclipse is the result of either an occultation (completely hidden) or a transit (partially hidden). 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 shadow of another moon. A binary star system can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth's orbit. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, which can happen only on the night of a full moon when the Moon is near either lunar node. The type and length of a lunar eclipse depend on the Moon's proximity to the lunar node. When the moon is totally eclipsed by the Earth, it takes on a reddish color that is caused by the planet when it completely blocks direct sunlight from reaching the Moon surface, as only the light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish due to the Rayleigh scattering of blue light, the same reason sunrise and sunsets are more orange than during the day. Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjunction (astronomy And Astrology)
In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When two objects always appear close to the ecliptic—such as two planets, the Moon and a planet, or the Sun and a planet—this fact implies an apparent close approach between the objects as seen in the sky. A related word, ''appulse'', is the minimum apparent separation in the sky of two astronomical objects. Conjunctions involve either two objects in the Solar System or one object in the Solar System and a more distant object, such as a star. A conjunction is an apparent phenomenon caused by the observer's perspective: the two objects involved are not actually close to one another in space. Conjunctions between two bright objects close to the ecliptic, such as two bright planets, can be seen with the naked eye. The astronomical symbol for conjunction is (Unicode U+260C ☌). The conjunction sym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logarithms
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 of is , or . The logarithm of to ''base'' is denoted as , or without parentheses, , or even without the explicit base, , when no confusion is possible, or when the base does not matter such as in big O notation. The logarithm base is called the decimal or common logarithm and is commonly used in science and engineering. The natural logarithm has the number as its base; its use is widespread in mathematics and physics, because of its very simple derivative. The binary logarithm uses base and is frequently used in computer science. Logarithms were introduced by John Napier in 1614 as a means of simplifying calculations. They were rapidly adopted by navigators, scientists, engineers, surveyors and others to perform high-accur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosthaphaeresis
Prosthaphaeresis (from the Greek ''προσθαφαίρεσις'') was an algorithm used in the late 16th century and early 17th century for approximate multiplication and division using formulas from trigonometry. For the 25 years preceding the invention of the logarithm in 1614, it was the only known generally applicable way of approximating products quickly. Its name comes from the Greek ''prosthesis'' (πρόσθεσις) and ''aphaeresis'' (ἀφαίρεσις), meaning addition and subtraction, two steps in the process. by Brian Borchers History and motivation In 16th-century Europe, celestial navigation of ships on long voyages relied heavily on |
Johannes Werner
Johann(es) Werner ( la, Ioannes Vernerus; February 14, 1468 – May 1522) was a German mathematician. He was born in Nuremberg, Germany, where he became a parish priest. His primary work was in astronomy, mathematics, and geography, although he was also considered a skilled instrument maker. Mathematics His mathematical works were in the areas of spherical trigonometry, as well as conic sections. He published an original work on conic sections in 1522 and is one of several mathematicians sometimes credited with the invention of prosthaphaeresis, which simplifies tedious computations by the use of trigonometric formulas, sometimes called Werner's formulas. Astronomy In 1500 he observed a comet, and kept observations of its movements from June 1 until the 24th. This work further developed the suggestion of Regiomontanus that the occurrences of eclipses and cometary orbits could be used to find longitude, giving a practical approach for this method by means of the cross-staff. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometric Identity
In trigonometry, trigonometric identities are Equality (mathematics), equalities that involve trigonometric functions and are true for every value of the occurring Variable (mathematics), variables for which both sides of the equality are defined. Geometrically, these are identity (mathematics), identities involving certain functions of one or more angles. They are distinct from Trigonometry#Triangle identities, triangle identities, which are identities potentially involving angles but also involving side lengths or other lengths of a triangle. These identities are useful whenever expressions involving trigonometric functions need to be simplified. An important application is the integral, integration of non-trigonometric functions: a common technique involves first using the Trigonometric substitution, substitution rule with a trigonometric function, and then simplifying the resulting integral with a trigonometric identity. Pythagorean identities The basic relationship betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean Baptiste Joseph Delambre
Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on the history of astronomy from ancient times to the 18th century. Biography After a childhood fever, he suffered from very sensitive eyes, and believed that he would soon go blind. For fear of losing his ability to read, he devoured any book available and trained his memory. He thus immersed himself in Greek and Latin literature, acquired the ability to recall entire pages verbatim weeks after reading them, became fluent in Italian, English and German and even wrote an unpublished ''Règle ou méthode facile pour apprendre la langue anglaise'' (Easy rule or method for learning English). Delambre's quickly achieved success in his career in astronomy, such that in 1788, he was elected a foreign member of the Royal Swedish Academy of Scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
