An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13070 Search : far
Poincaré sphere
  کره‌ی ِ پو‌آنکاره   
kore-ye Poincaré

Fr.: sphère de Poincaré   

A representation that permits an easy visualisation of all different states of → polarization of a vector wave. The equator represents → linear polarization; the north pole corresponds to right-circular and the south pole to left- → circular polarization.

Named after Henri Poincaré (1854-1912), French mathematician and theoretical physicist, and a philosopher of science; → sphere.

Poinsot's motion
  جنبش ِ پویءنسو   
jonbeš-e Poinsot

Fr.: mouvement à la Poinsot   

The motion of a torque free rotating rigid body in space, in general whose angular velocity vector precesses regularly about the constant angular momentum factor.

After Louis Poinsot (1777-1859), French physicist and mathematician. He was the inventor of geometrical mechanics, showing how a system of forces acting on a rigid body could be resolved into a single force and a couple.

point
  ۱) نقطه، پنده؛ ۲) آماجیدن   
1) noqté (#), pandé (#); 2) âmâjidan

Fr.: 1) point; 2) pointer   

1a) General: A sharp or tapering end, as of a dagger; a projecting part of anything.
1b) Physics: Position or time of occurrence, as in boiling point, freezing point, etc.
1c) Math.: A dimensionless geometric element whose location in space is defined solely by its coordinates.
2) To direct a telescope toward a particular position on the sky.

M.E. point(e); O.Fr. point "dot, mark, place, moment;" L. punctum noun use of neuter p.p. of pungere "to prick, pierce."

1) Noqté, loan from Ar. Pandé, variants in classical dictionaries pindé, pendé, fand "a point, dot, mole, freckle;" cf. Skt. prānta- "point, tip, border," from pra "before, forward," → pro-, + ánta- "end, limit, term;" Pali, panta- "remote, solitary;" Prakrit panta " last;" Sindhi pandu "border of a garment;" Lahnda pand, pad "end, top of sugar cane."
2) Âmâjidan, verb from âmâj "aim, goal," from Proto-Iranian base *āma-, from prefix *ā- + *ma- "to measure;" cf. Av. mati- "point, tip;" O.Pers./Av. mā(y)- "to measure;" Pers. mun/mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl;" cf. Skt. mati "measures," matra- "measure," Gk. metron "measure," L. metrum; PIE base *me- "to measure."

point mass
  نقطه‌جرم، پنده‌جرم، جرم ِ نقطه‌وار، ~ پنده‌وار   
noqté jerm, pandé jerm, jerm-e noqtevâr, ~ pandevâr

Fr.: masse ponctuelle   

A hypothetical object which can be thought of as infinitely small.

point; → mass.

point source
  نقطه‌خن، پنده‌خن، خن ِ نقطه‌وار، ~ پنده‌وار   
noqté xan, pandé xan, xan-e noqtevâr, pande-ye ~

Fr.: source ponctuelle   

A source of radiation at a great distance from the observer; an ideal source of infinitesimal size.

point; → source.

point spread function (PSF)
  کریای ِ گسترش ِ نقطه، ~ ~ پنده   
karyâ-ye gostareš-e noqté, ~ ~ pandé

Fr.: fonction d'étalement du point   

The two-dimensional intensity distribution about the image of a point source.

point; → spread; → function.

Pointers
  دورهنما   
dorahnemâ

Fr.:   

The two stars that form the front of the Big Dipper's bowl, away from the handle. More specifically, the stars Dubhe (α Ursae Majoris) and Merak (β Ursae Majoris). A line through β to α passes close to the North Star and they are used for finding it.

point + -er.

Dorahnemâ, literally "the two guides," from do "two" + rah, râh "way, path" (from Mid.Pers. râh, râs "way, street," also rah, ras "chariot;" from Proto-Iranian *rāθa-; cf. Av. raθa- "chariot;" Skt. rátha- "car, chariot," rathyā- "road;" L. rota "wheel," rotare "to revolve, roll;" Lith. ratas "wheel;" O.H.G. rad; Ger. Rad; Du. rad; O.Ir. roth; PIE *roto- "to run, to turn, to roll") + nemâ agent noun of nemudan "to show" (Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into" (Skt. ni "down," nitaram "downward," Gk. neiothen "from below," cf. E. nether, O.E. niþera, neoþera "down, downward, below, beneath," from P.Gmc. *nitheraz, Du. neder, Ger. nieder; PIE *ni- "down, below") + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure").

pointing
  آماجش   
âmâješ

Fr.: 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 âmâješ

Fr.: 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   
poise

Fr.: poise   

The unit of viscosity in the c.g.s. system, equal to 1 dyne.s/cm2. Symbol: P

Poise, 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 Poiseuille

Fr.: 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 Poisson

Fr.: 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)/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 Poisson

Fr.: équation de Poisson   

An equation (∇2φ = 4πGρ) which relates the gravitational (or electromagnetic) potential to the mass density (or charge density).

Poisson distribution; → equation.

polar
  ۱) قطبی؛ ۲) پلار   
1) qotbi; 2) polâr

Fr.: 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 qotbi

Fr.: 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 qotbi

Fr.: 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 qotbi

Fr.: 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.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut aut axi Baa bal Bal bar bar bea beh Bes bia big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo Cal cal Can cap car Car cat cat CCD Cen cen CGS cha cha che che chr cir cir cis cla clo clo clu coa coe coh col col col com com com com com com com com Com con con con con con con con con con con con con Cop Cor cor cor cos cos Cou cou cov cre cri cro cry cur cut Cyg DA dar dat de deb dec dec ded def def dei dem den dep des det dev dia dif dif dig Dio Dir dis dis dis dis dis dis div dom dou dow dri dur dus dyn dyn ear eav ecl Edd eff Ein Ekm ele ele ele ele ell emb emi enc ene ent eph equ equ equ eru eth eup eve EX exc exe exi exo exp ext ext ext fab fai far Fec fem fer fie fin fir fis fla flo flu foc for for Fou fra fre fre fro fun G r Gal gal gam gas Gau gel gen geo geo geo Gho gla goa gra gra gra gra gre Gre gro gyr had hal har har HD Hea Hel hel Her her hid hig hip hol hor hos hov Hub Hun hyd hyd hyd hyp IC ide ill ima imp imp inc inc ind ind inf inf inf inf inj InS ins int int int int int int int int int inv ion iro ise iso iso ite jet Jou Jup kap Kep kil Kip Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea med men mer Mes met met mic Mic Mie Mil min mis mJy mod mol mon moo mot mul mul mut nad nas nat neb neg net neu New New nig Noe non non non Nor nov nuc nul num OB obl obs occ Ock off Ohm on- ope opi opt opt orb orb ord Ori ort osm out ove ozo pal pan par par par par pat pec pen per per per per per Pfu pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua qui rad rad rad rad rad rad rai ran Ras Ray rea rec rec rec red red ref reg reg rel rel rel rep res res res res Reu rhe Rie rig ris Roe Ros rot Rud ryd Sag sam sat sca sca Sch sci Sea sec sec see sel sem sen ser Sey Sha she sho sid sig sim sim sin ske sle smo Sob sof sol sol sol sol sou Sou spa Sp spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver ver vin vir vis Vog von wal wat wav wax wea wei Whi wil win WN7 wor X-r Yar You zer zod > >>