# 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: 1965 Search : ion
 equation of time   هموگش ِ زمان   hamugeš-e zamânFr.: équation du temps   The difference, due to Earth's elliptical orbit and variable orbital velocity, between apparent solar time and mean solar time. It varies throughout the year, and slightly from year to year. At present, it reaches extremes of about -14 minutes in February, and about +16 minutes in November. The equation of time is visually illustrated by an → analemma.→ equation; → time. equilibrium partitioning   پرکه‌بندی ِ ترازمند   parkebandi-ye tarâzmandFr.: équilibre de partition   A concept whereby chemical → concentrations among geological or environmental media are at equilibrium, and therefore the partitioning of metals in those media can be predicted based on → partition ratios. equilibrium position   نهش ِ ترازمندی   naheš-e tarâzmandi (#)Fr.: position d'équilibre   The position of an oscillating body at which no net force acts on it.→ equilibrium; → position. equipartition of energy   هموگپرکش ِ کاروژ   hamugparkeš-e kâružFr.: équipartition de l'énergie   1) General: Equal sharing of the → total energy among all → components of a → system. 2) In the → kinetic theory of gases, the → theorem according to which → molecules in → thermal equilibrium have the same average energy (1/2 kT) associated with each independent → degree of freedom of their motion.→ equi-; → partition. equivalent positions   نهش‌های ِ هموگ‌ارز   nehešhâ-ye hamug-arzFr.:   Complete set of points in any given space group which are obtained by performing the symmetry operations of the space group on a single point (x, y, z).→ equivalent; → position. erosion   فرسایش   farsâyeš (#)Fr.: érosion   Geology: The act or state of eroding; state of being eroded. A general term applied to the wearing away and movement of earth materials by the action of water, glaciers, winds, gravity, etc.From M.Fr. erosion, from L. erosionem (nom. erosio), from erodere "to gnaw away," from → ex- "away" + rodere "to gnaw, eat away" (cf. Fr. and E. animal rat).Farsâyeš, from far- intensive prefix "much, abundant" (Mid.Pers. fra- "forward, before; much; around;" O.Pers. fra- "forward, forth;" Av. frā, fərā-, fra- "forward, forth; excessive;" cf. Skt. prá- "before; forward, in fron;" Gk. pro "before, in front of;" L. pro "on behalf of, in place of, before, for;" PIE *pro-) + verbal noun of sâyidan, variants sâbidan "to bruise, file," pasâvidan "to touch;" Khotanese sauy- "to rub;" Sogdian ps'w- "to touch;" Proto-Iranian *sau- "to rub." eruption   اسدرش   osdarešFr.: éruption   1) An act, process, or instance of erupting; something that is erupted or ejected. 2) → flare. 3) Geology: The ejection of molten rock, steam, etc., as from a volcano or geyser.Verbal noun of → erupt. estimation   بر‌آوری   barâvari (#)Fr.: estimation   Statistics: The process by which sample data are used to indicate the value of an unknown quantity in a population.Verbal noun of → estimate. Euclidean division   بخش ِ اقلیدوسی   baxš-e OqlidosiFr.: division euclidienne   In arithmetic, the conventional process of division of two → integers. For a → real number a divided by b > 0, there exists a unique integer q and a real number r, 0 ≤ r