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

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

Homepage

Number of Results: 13116 Search : far
 pointing   آماجش   âmâješFr.: pointage   The act or process of directing a telescope. → point. The direction in the sky to which the telescope is pointed. Pointing also describes how accurately a telescope can be pointed toward a particular direction in the sky.Verbal noun of → point. pointing model   مدل ِ آماجش   model-e âmâješFr.: modèle de pointage   A mathematical model that reproduces the diurnal rotation of the Earth and is used to direct a telescope toward a precise position on the sky.→ pointing; → model. poise   پو‌آز   poiseFr.: poise   The unit of viscosity in the c.g.s. system, equal to 1 dyne.s/cm2. Symbol: PPoise, from Jean-Louis-Marie Poiseuille (1797-1869), a French physiologist and physician who studied the flow of liquids through tubes and developed a method for measuring blood pressure. Poiseuille's law   قانون ِ پو‌آزوی   qânun-e PoiseuilleFr.: loi de Poiseuille   In fluid dynamics, the law that the rate of flow of a liquid through a horizontal tube of uniform radius is directly proportional to the pressure of the liquid and the fourth power of the radius of the tube and is inversely proportional to the viscosity of the liquid and the length of the tube.Named after Jean-Louis-Marie Poiseuille (1797-1869), a French physiologist and physician who found the law in 1844; → law. Poisson distribution   واباژش ِ پو‌آسون   vâbâžeš-e PoissonFr.: distribution de Poisson   A → probability function that characterizes → discrete  → random events occurring independently of one another within some definite time or space. It may be regarded as an approximation of the → binomial distribution when the number of events becomes large and the probability of success becomes small. The Poisson distribution is expressed by: f(x) = (λxe-λ)/x!, where λ is the mean number of successes in the interval, e is the base of the → natural logarithm, and x is the number of successes we are interested in.Named after Siméon Denis Poisson (1781-1840), French mathematician, who developed the application of Fourier series to physical problems and made major contributions to the theory of probability and to the calculus of variations; → distribution. Poisson's equation   هموگش ِ پو‌آسون   hamugeš-e PoissonFr.: équation de Poisson   An equation (∇2φ = 4πGρ) which relates the gravitational (or electromagnetic) potential to the mass density (or charge density). polar   ۱) قطبی؛ ۲) پلار   1) qotbi; 2) polârFr.: 1) polaire; 2) polar   1) Of or pertaining to the pole of any sphere, a magnet, an electric cell, etc. 2) A subclass of → cataclysmic variables, the prototype being AM Herculis. Polars are short-period systems in which a → late-type → main sequence star transfers mass to a highly magnetized → white dwarf. The strong magnetic field (10-70 million → gauss) prevents the formation of an → accretion disk, locks both stars in synchronous rotation and guides the accreting matter to accretion spots which are the source of intense X-ray radiation (material impacts on to the white dwarf where it is radiated away).1) Adj. of → pole. 2) From polar(ization) + (st)ar, because of their → circularly polarized light. polar alignment   آخطش ِ قطبی   âxateš-e qotbiFr.: alignement polaire   The process or the state of making a → telescope's → polar axis → parallel to the → Earth's → rotation axis, that is with the → true North or → South  → celestial pole. When this is accomplished, the sky's motion can be cancelled out simply by turning the axis (either by hand or with a motor → drive) at the same rate as the rotation of the Earth, but in the opposite direction.→ polar; → alignment. polar axis   آسه‌ی ِ قطبی   âse-ye qotbi (#)Fr.: axe polaire   The axis of an → equatorial mounting that is parallel to the Earth's axis, and consequently points to the celestial pole.→ polar; → axis. polar bond   بند ِ قطبی   band-e qotbiFr.: lien polaire   A chemical bond where the electrons are shared unequally between atoms. The atom that is more electronegative will pull the electrons closer to itself.→ polar; → bond. polar cap   کلاهک ِ قطبی   kolâhak-e qotbiFr.: calotte polaire   1) Either of the regions around the poles of the Earth that are permanently covered with ice. 2) Either of the two regions around the poles of the planet Mars, consisting of frozen carbon dioxide and water ice. 3) An area of a → pulsar's surface from where open magnetic field lines emanate.→ polar; → cap. polar circle   پرهون ِ قطبی، دایره‌ی ِ ~   parhun-e qotbi, dâyere-ye ~ (#)Fr.: cercle polaire   An imaginary parallel circle on the celestial sphere or on the Earth at a distance of 23°.5 from either poles.→ polar; → circle. polar coordinates   هم‌آراهای ِ قطبی   hamârâhâ-ye qotbi (#)Fr.: coordonnées polaires   A coordinate system in which the position of any point (M) in a plane is specified by two coordinates: 1) ρ, which expresses the distance from a fixed point (the pole, denoted O), and 2) the number φ, which is the angle formed by the line segment OM and a fixed reference line passing through the pole.→ polar; → coordinate. polar cusp   تیزه‌ی ِ قطبی   tize-ye qotbiFr.: cuspide polaire   An area in the Earth's → magnetosphere, where the → magnetosheath plasma has direct access to the → ionosphere.→ polar; → cusp. polar day   روز ِ قطبی   ruz-e qotbi (#)Fr.: jour polaire   In polar regions, the portion of the year when the Sun is continuously in the sky. Its length changes from twenty hours at the Arctic/Antarctic Circle (latitude 66°33' N or S) to 186 days at the North/South Pole.→ polar; → day. polar distance   دورای ِ قطبی   durâ-ye qotbiFr.: distance polaire   The angular distance of an object from a celestial pole. It is equal to 90° minus the object's declination.→ polar; → distance. polar equation   هموگش ِ قطبی   hamugeš-e qotbiFr.: équation polaire   An equation for a curve written in terms of the → polar coordinates.→ polar; → equation. polar faculae   پریسک‌های ِ قطبی   periskhâ-ye qotbiFr.: facules polaires   Solar faculae occurring in regions of high heliographic latitudes. They are smaller than the main-zone faculae; their shape is point-like or oval. Their lifetimes range from a few minutes to some hours, but the decisive difference from the main-zone faculae lies in their activity cycle. When spots and faculae of the main zone are at minimum, the polar faculae have their maximum activity, and vice versa.→ polar; → facula. polar molecule   مولکول ِ قطبی   molekul-e qotbiFr.: molécule polaire   A molecule in which the centers of positive and negative charge distribution do not converge and therefore has a mostly positive charge on one side and a mostly negative charge on the other. Different atoms around a central atom will always be polar molecules. Some polar molecules are H2O, HF, COS, and CH3Cl. Polar molecules are characterized by a → dipole moment.→ polar; → molecule. polar motion   جنبش ِ قطبی   jonbeš-e qotbiFr.: mouvement du pôle   The irregularly varying motion of the Earth's pole of rotation with respect to the Earth's crust.→ polar; → motion.