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

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

Homepage

Number of Results: 438
 grating efficiency   کار‌آیی ِ توری   kârâyi-ye turi (#)Fr.: efficacité de réseau   The measure of the light intensity diffracted from a grating.→ grating; → efficiency. grating groove   شیار ِ توری   šiyâr-e turi (#)Fr.: trait du réseau, sillon ~ ~   One of thousands of long, narrow indentations in the surface of a → diffraction grating.→ grating; → groove. gravitate   گرانیدن   gerânidan (#)Fr.: graviter   To move or tend to move under the influence of gravitational force.From L. gravitatus, p.p. of gravitâre, from gravis "heavy," → gravity.Gerânidan, infinitive of gerân, → gravity. gravitation   گرانش   gerâneš (#)Fr.: gravitation   1) The universal phenomenon of attraction between material bodies. → Newton's law of gravitation. 2) The act or process of moving under the influence of this attraction.Verbal noun of → gravitate. gravitational   گرانشی   gerâneši (#)Fr.: gravitationnel   Of or relating to or caused by → gravitation.Adj. of → gravitation. gravitational acceleration   شتاب ِ گرانشی   šetâb-e gerâneši (#)Fr.: accélération gravitationnelle   The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity. gravitational attraction   درکشش ِ گرانشی   darkešeš-e gerânešiFr.: attraction gravitationnelle   The force that pulls material bodies toward one another because of → gravitation. gravitational collapse   رمبش ِ گرانشی   rombeš-e gerâneši (#)Fr.: effondrement gravitationnel   Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents. gravitational constant   پایای ِ گرانشی   pâyâ-ye gerâneši (#)Fr.: constante gravitationnelle   A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10-8 dyn cm2 g-2 or 6.673 x 10-8 cm3s-2g-1, or 6.673 x 10-11 N m2 kg-2 or 6.673 x 10-11 m3s-2kg-1. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation. gravitational contraction   ترنگش ِ گرانشی   terengeš-e gerânešiFr.: contraction gravitationnelle   Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force. gravitational coupling constant   پایای ِ جفسری ِ گرانشی   pâyâ-ye jafsari-ye gerânešiFr.: constante de couplage gravitationnel   The dimensionless gravitational constant defined as the gravitational attraction between pair of electrons and normally given by: αG = (Gme2) / (ħc) = (me / mP)2 ~ 1.7518 × 10-45, where ħ is → Planck's reduced constant, c the → speed of light, me is the → electron mass, and mP is the → Planck mass.→ gravitational; → coupling; → constant. gravitational encounter   رویارویی ِ گرانشی   ruyâruyi-ye gerânešiFr.: rencontre gravitationnelle   An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction. gravitational energy   کاروژ ِ گرانشی   kâruž-e gerânešiFr.: énergie gravitationnelle   Same as → gravitational potential energy.→ gravitational; → energy. gravitational equilibrium   ترازمندی ِ گرانشی   tarâzmandi-ye gerâneši (#)Fr.: équilibre gravitationnel   The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results. gravitational field   میدان ِ گرانشی   meydân-e gerâneši (#)Fr.: champ gravitationnel   The region of space in which → gravitational attraction exists.→ gravitational; → field. gravitational force   نیروی ِ گرانشی   niru-ye gerâneši (#)Fr.: force gravitationnelle   The weakest of the four fundamental forces of nature. Described by → Newton's law of gravitation and subsequently by Einstein's → general relativity.→ gravitational; → force. gravitational instability   ناپایداری ِ گرانشی   nâpâydâri-ye gerâneši (#)Fr.: instabilité gravitationnelle   The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation. gravitational interaction   اندرژیرش ِ گرانشی   andaržireš-e gerânešiFr.: interaction gravitationnelle   Mutual attraction between any two bodies that have mass. gravitational lens   عدسی ِ گرانشی   adasi-ye gerâneši (#)Fr.: lentille gravitationnelle   A concentration of matter, such as a galaxy or a cluster of galaxies, that bends light rays from a background object, resulting in production of multiple images. If the two objects and the Earth are perfectly aligned, the light from the distant object appears as a ring from Earth. This is called an Einstein Ring, since its existence was predicted by Einstein in his theory of general relativity.→ gravitational; → lens. gravitational lens equation   هموگش ِ عدسی ِ گرانشی   hamugeš-e adasi-ye gerânešiFr.: équation de lentille gravitationnelle   The main equation of gravitational lens theory that sets a relation between the angular position of the point source and the observable position of its image.→ gravitational; → lens; → equation.