# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 97
 Kepler   کپلر   Kepler (#)Fr.: Kepler   Johannes Kepler (1571-1630), a German mathematician and astronomer and a key figure in the 17th century astronomical revolution. He discovered that the Earth and planets travel about the Sun in elliptical orbits; gave three fundamental laws of planetary motion, and also did important work in optics and geometry. Kepler problem   پراسه‌ی ِ کپلر   parâse-ye KeplerFr.: problème de Kepler   1) Given the trajectory of a particle moving in a → central force field, determine the law governing the central force. 2) Inversely, considering a central force -k/r2, determine the trajectory a particle moving in the field will take.→ Kepler; → problem. Kepler spacecraft   تلسکوپ ِ فضایی ِ کپلر   teleskop-e fazâyi-ye KeplerFr.: télescope spatial de Kepler   A → NASA space telescope launched in March 2009 to discover Earth-size planets using the → transit method. The telescope has a diameter of 0.95 m and its only instrument is a → photometer that continuously monitors the brightness of over 145,000 → main sequence stars in a fixed field of view of 115 deg2 (about 12° diameter). The expected mission lifetime is 3.5 years extendible to at least 6 years.In honor of Johannes → Kepler; → spacecraft. Kepler's equation   هموگش ِ کپلر   hamugeš-e KeplerFr.: équation de Kepler   An equation that enables the position of a body in an elliptical orbit to be calculated at any given time from its orbital elements. It relates the → mean anomaly of the body to its → eccentric anomaly.Keplerian, adj. of → Kepler; → equation. Kepler's first law   قانون ِ نخست ِ کپلر   qânun-e naxost-e Kepler (#)Fr.: première loi de Kepler   Planets move in elliptical paths, with the Sun at one focus of the ellipse (year 1609).→ Kepler; → first; → law. Kepler's laws   قانون‌های ِ کپلر   qânunhâ-ye Kepler (#)Fr.: lois de Kepler   1) The planets move about the Sun in ellipses, at one focus of which the Sun is situated. 2) The → radius vector joining each planet with the Sun describes equal areas in equal times. 3) The ratio of the square of the planet's period of revolution to the cube of the planet's mean distance from the Sun is the same for all planets.→ Kepler; → law. Kepler's second law   قانون ِ دوم ِ کپلر   qânun-e dovom-e Kepler (#)Fr.: deuxième loi de Kepler   A line joining a planet to the Sun sweeps out equal areas in equal intervals of time (year 1609).→ Kepler; → second; → law. Kepler's star   ستاره‌ی ِ کپلر   setâre-ye Kepler (#)Fr.: étoile de Kepler   A → supernova in → Ophiuchus, first observed on 1604 October 9, and described by Johannes Kepler in his book De stella nova (1606). It reached a maximum → apparent magnitude of -3 in late October. The star remained visible for almost a year. The → light curve is that of a → Type Ia supernova. The → supernova remnant consists of a few filaments and brighter knots at a distance of about 30,000 → light-years. It is the radio source 3C 358. Also known as SN 1604 and Kepler's supernova.→ Kepler; → star. Kepler's third law   قانون ِ سوم ِ کپلر   qânun-e sevom-e Kepler (#)Fr.: troisième loi de Kepler   The ratio between the square of a planet's → orbital period (P) to the cube of the mean distance from the Sun (a) is the same for all planets: P2∝ a3 (year 1618). More accurately, P2 = (4π2a3) / [G(M1 + M2)], where M1 and M2 are the masses of the two orbiting objects in → solar masses and G is the → gravitational constant. In our solar system M1 = 1. The → semi-major axis size (a is expressed in → astronomical units and the period (P) is measured in years.→ Kepler; → third; → law. Keplerian   کپلری   KepleriFr.: keplerien   Of or pertaining to Johannes Kepler or to his works or discoveries.From → Kepler + -ian a suffix forming adjectives. Keplerian angular velocity   تندای ِ زاویه‌ای ِ کپلری   tondâ-ye zâviye-yi-ye KepleriFr.: vitesse angulaire keplérienne   The angular velocity of a point in a circular orbit around a central mass. It is given by: ΩK = (GM/r3)1/2, where G is the → gravitational constant, M is the mass of the gravitating object, and r is the radius of the orbit of the point around the object.→ Keplerian; → angular; → velocity. Keplerian disk   گرده‌ی ِ کپلری، دیسک ِ ~   gerde-ye Kepleri, disk-e ~Fr.: disque keplérien   A circumstellar disk (such as an → accretion disk or a → protoplanetary disk) in which the → angular velocity at each radius is equal to the angular velocity of a circular → Keplerian orbit at the same radius. The main characteristic of the Keplerian disk is that → orbital velocity varies as r-1/2. This means that an object on an orbit closer to the central mass turns more rapidly than that on a farther orbit. This velocity difference is at the origin of internal friction or kinematic viscous forces between disk particles, which heats up the material.→ Keplerian; → disk. Keplerian orbit   مدار ِ کپلری   madâr-e Kepleri (#)Fr.: orbit keplérienne   The orbit of a spherical object of a finite mass around another spherical object, also of finite mass, governed by their mutual → gravitational forces only.→ Keplerian; → orbit. Keplerian orbital velocity   تندای ِ مدار ِ کپلری   tondâ-ye madâr-e KepleriFr.: vitesse d'orbite képlérienne   The velocity of an object orbiting another object according to → Kepler's laws.→ Keplerian; → orbital; → velocity. Keplerian rotation curve   خم ِ چرخش ِ کپلری   xam-e carxeš-e Kepleri (#)Fr.: courbe de rotation keplérienne   A → rotation curve in which the speed of the orbiting body is inversely proportional to the → square root of its distance from the mass concentrated at the center of the system.→ Keplerian; → rotation; → curve. Keplerian shear   کرن ِ کپلری   karn-e KepleriFr.: cisaillement keplerien   Shearing motion of an ensemble of particles, each on a nearly circular, → Keplerian orbit. → Orbital velocity decreases as orbital radius increases, yielding shear. Viscous drag on such shear, due to ring-particle collisions, plays a key role in ring processes (Ellis et al., 2007, Planetary Ring Systems, Springer).→ Keplerian; → shear. Keplerian telescope   دوربین ِ کپلر، تلسکوپ ِ ~   durbin-e Kepler, teleskop-e ~ (#)Fr.: télescope de Kepler   A → refracting telescope which has simple → convex lenses for both → objective and → eyepiece. It suffers from → chromatic aberration, which can be reduced by increasing the → focal ratio. It was first devised by Kepler in 1615.→ Keplerian; → telescope. Kerberos   کربروس   KerberosFr.: Kerberos   The fourth → natural satellite of → Pluto discovered in 2011 using the → Hubble Space Telescope. Also called Pluto IV (P4). It has an estimated diameter of 14-44 km, which makes it the second smallest known moon of Pluto after → Styx. Kerberos revolves around Pluto in the region between → Nix and → Hydra at a distance of about 58,000 km and makes a complete orbit roughly every 32.1 days.Named after the three-headed dog of Greek mythology. kernel   ا َستل   astelFr.: noyau   1) Chemistry: The remainder of an atom after the valence electrons have been removed. 2a) Math.: 1) The set of elements that a given function from one set to a second set maps into the identity of the second set. 2b) Let A be a linear transformation of the vector space U into the vector space V . The collection of all those vectors x in U such that Ax = 0 is called the kernel of A and is denoted by ker(A). 3) Computers: The set of functions that make up the operating system, the core that provides basic services for all other parts of the operating system. → core = maqzé (مغزه); → nucleus = hasté (هسته).Kernel, from M.E. kirnel, from O.E. cyrnel, from P.Gmc. *kurnilo- (cf. M.H.G. kornel, M.Du. cornel), from *kernan- (root of corn "seed, grain"), akin to L. granium, + -el, diminutive suffix, variant of → -al.Astel, from asté "kernel, fruit stone," variants hasté, ostoxân "bone," from Mid.Pers. astak "fruit stone, bone," ast "bone;" Av. ast- "bone;" cf. Skt. asthi- "bone;" Gk. osteon; L. os; Hittite hashtai-; PIE base *os- + Pers. diminutive suffix -el→ -al. Kerr black hole   سیه‌چال ِ کر   siyah câl-e Kerr (#)Fr.: trou noir de Kerr   A → black hole that possesses only mass (not electric charge) and rotates about a central axis. It has an → ergosphere and a → stationary limit.Named after the New Zealand mathematician Roy P. Kerr (1934-) who, in 1963, was the first to solve the → field equationss of Einstein's theory of → general relativity for a situation of this kind; → black hole.