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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < -es -iv -ti 217 a- abe abs abs acc acc ach act act ada adi adv aff agg Alc Alf ali all alp alt Ama amp ana ang ang ann ano ant ant ape apo app aps arc arg arm art ass ast ast ast atm ato att aur aut axi B-t bai Bal bar bar Be bee Bes bi- bif bin bin bio bis bla bli blu Boe Bol bor bou bra bri Bro bum CAI cal Can cap car car cat cat CCD Cel cen CGS cha cha che che chr cir cir civ cla clo clo CMB 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 coo cor cor cor cos cos cos cou cov cra cri cro cry cum cur cyc d'A dar dat DC dea dec dec dec def def deh Del den dep des det dev dia dif dif dif dim dip dir dis dis dis dis dis div dom dou dou dri dup dus dyn dyn ear eas 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 fac fal far fec Fer fer fie fin fir fis fla flo flu fog for for Fou fra fre Fre Fro fus G-t gal gal Gam gas Gau Gem gen geo geo geo gia gla gol gra gra gra gra Gre Gre gui H a haf Hal har har He- hea hel Hel her Her hie hig his hom hor hot Hub Hug hur hyd hyd hyl hyp ice ide ima imp imp imp inc ind ind ine inf inf Inf inj InS ins int int int int int int int int inv inv ion iro Isl iso iso Jac jet jud jur Kel Kep kil kly L d Lag lam Lap lar lat law Lea len lep lib lig lin lin lin liq lit loc log lon Los low lum lun Lut Lyr mac mag mag mag mag mag maj man Mar mas mas mat mea mec mem mer mes met met met mic mid mil min Mir Miz mod mol mon moo MOS mul mul mut nai nas nat neb neg Neu neu New New Nih noi non non non nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove oxi pac Pal par par Par par pas Pau Pel per per per per per per pha phi pho pho pho phy pip Pla pla pla pla pla Plu Poi pol pol pol pop pos pos pot Pra pre pre pre Pri pri pri pro pro pro pro pro pro pro Pto pul puz 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 rev rhe Rie Rig Rit roe Ros rot Ruf Ryd Sag sam sat sca sca Sch Sco sec sec sec seg sel sem sen set sha SHB sho sib sie sil sim sin sit sky slo sno sod sol sol sol sol sor sou Spa spa spe spe spe sph spi Spi spr sta sta sta sta sta ste ste Ste sto str str sub sub sub suf sun sup sup sup sup sur swo syn sys tak Tay Tel ten ter tet the the the thi Tho thu tid tim toa top tot tra tra tra tra tri tri tro Tru tur twi Typ UBV ult unb uni uni uni up ura uti val var vec Vel ver ver vig vir vis VLT vol wad was wav wav wea wei Whe Wie win WN5 Wol X-r yea You zer zod > >>

Number of Results: 12929 Search : far
Ritchey-Chretien telescope
  تلسکوپ ِ ریچی-کرتین، دوربین ِ ~   
teleskop-e Ritchey-Chrétien, durbin-e ~

Fr.: télescope Ritchey-Chrétien   

A type of → Cassegrain telescope in which the → primary mirror is a → hyperboloid. It is designed to eliminate → coma and → spherical aberration, thus providing a relatively large field of view as compared to a more conventional configuration.

Named after the American astronomer George Ritchey (1864-1945) and the French optician Henri Chrétien (1879-1956); → telescope.

Ritz combination principle
  پروز ِ میازش ِ ریتز   
parvaz-e miyâzeš-e Ritz

Fr.: principe de combinaison de Ritz   

An empirical rule discovered before the advent of quantum mechanics which states that it is possible to find pairs of spectral lines, which have the property that the sum of their wavenumbers is also an observed spectral line.

Named after Walther Ritz (1878-1909), a Swiss theoretical physicist; → combination; → principle.

rival
  هماورد   
hamâvard (#)

Fr.: rival   

1) A person who is competing for the same object or goal as another, or who tries to equal or outdo another; competitor.
2) A person or thing that is in a position to dispute another's preeminence or superiority (Dictionary.com).

From L. rivalis "a rival, adversary; neighbor," originally, "one who uses a stream in common with another," from riv(us) "stream, brook," + -alis, → -al.

Hamâvard "a rival; an adversary in a combat," from ham- "together," → com-, + âvard "battle, struggle," variants nabard, nibard, nâvard "fight, struggle, war," ultimately from Proto-Ir. *part- "to fight, to struggle."

rivalry
  هماوردی   
hamâvardi (#)

Fr.: rivalité   

1) The action, position, or relation of a rival or rivals; competition.
2) An instance of this (Dictionary.com).

Noun from → rival.

river
  رود   
rud (#)

Fr.: rivière   

A large natural stream of water flowing in a definite course.

M.E., from O.Fr. rivere, riviere, from V.L. *riparia "riverbank, seashore, river," noun use of feminine of L. riparius "of a riverbank."

Rud, from Mid.Pers. rôd "river," O.Pers. rautah- "river;" cf. Skt. srotas- "river," sru- "to flow;" Pali sota- "stream, flood;" Gk. rhoos "a stream, a flowing," from rhein "to flow;" O.E. stream; Ger. Strom; PIE base *sreu- "to flow."

roAp star
  ستاره‌ی Apی ِ تند نونده   
setâre-ye Ap-ye tond navandé

Fr.: étoile Ap à oscillation rapide   

Same as → rapidly oscillating Ap star

rapidly oscillating Ap star

Robertson-Walker metric
  متریک ِ روبرتسون-واکر   
metrik-e Robertson-Walker (#)

Fr.: métrique de Robertson-Walker   

The mathematical description of the interval (→ space-time separation) between → events ("points" in space-time) in a → homogeneous and → isotropic → Universe. It results from an exact solution of → Einstein's field equations of → general relativity. Under the assumptions, the Robertson-Walker interval is expressed by:
ds2 = c2dt2 - R2(t) [dr2/(1 - kr2) + r22 + r2sin2θ dθ2)].
Same as Friedmann-Lemaître-Robertson-Walker metric. Compare → Minkowski metric.

Named after Howard Percy Robertson (1903-1961), American mathematician and physicist, and Arthur Geoffrey Walker (1909-2001), British mathematician and physicist, for their contributions to physics and physical cosmology; → metric.

robot
  روبوت   
robot (#)

Fr.: robot   

A machine that does mechanical, routine tasks on command.

From Czech, coined by Karel Čapek in the play R.U.R. (1920), from the base robot-, as in robota "compulsory labor," robotník "peasant owing such labor," from robotiti "to work, drudge."

Robot, loan from E., as above.

robust
  تناور   
tanâvar (#)

Fr.: robuste   

The quality of a model when it is insensitive to small discrepancies in assumptions.

From L. robustus "strong and hardy," literally "as strong as oak," from robur, robus "hard timber, strength," also "a special kind of oak," named for its reddish heartwood, from L. ruber, → red.

Tanâvar "robust, stout, corpulent," from tan "corpus, body," → if and only if + âvar contraction of âvarandé agent noun of âvardan "to bring; to cause, produce," → collect.

Roche limit
  حد ِ رُش   
hadd-e Roche

Fr.: rayon de Roche   

The smallest distance at which a → satellite under the influence of its own → gravitation and that of a central mass about which it is describing a → Keplerian orbit can be in equilibrium. This does not, however, apply to a body held together by the stronger forces between atoms and molecules. At a lesser distance the → tidal forces of the → primary body would break up the → secondary body. The Roche limit is given by the formula d = 1.26 RMMm)1/3, where RM is the radius of the → primary body, ρM is the → density of the primary, and ρm is the density of the secondary body. This formula can also be expressed as: d = 1.26 Rm (MM/Mm)1/3, where Rm is the radius of the secondary. As an example, for the Earth-Moon system, where RM = 6,378 km, ρM = 5.5 g cm-3, and ρm = 2.5 g cm-3 is 1.68 Earth radii.

Named after Edouard Albert Roche (1820-1883), the French astronomer who first calculated this theoretical limit in 1848; → limit.

Roche lobe
  لپ ِ رُش   
lap-e Roche

Fr.: lobe de Roche   

The region around a star in a → binary system within which orbiting material is gravitationally bound to that star. The point at which the Roche lobes of the two stars touch is called the → inner Lagrangian point. → equipotential surface.

Roche limit; → lobe.

Roche lobe overflow (RLOF)
  سرریز ِ لپ ِ رُش   
sarriz-e lap-e Roche

Fr.: débordement du lobe de Roche   

A process in a → binary system when a star fills its → Roche lobe, often by becoming a → giant or → supergiant during the later stages of → stellar evolution. When the star expands, any material that passes beyond the Roche lobe will flow onto the binary → companion, often by way of an → accretion disk. This occurs through the → inner Lagrangian point where the gravity of the two stars cancels. The RLOF is responsible for a number of phenomena including → cataclysmic variables, → Type Ia supernovae, and many → X-ray binary systems.

Roche lobe; → overflow.

rock
  برد، سنگ   
bard (#), sang (#)

Fr.: roche   

1) A large mass of → stone forming a hill, cliff, promontory, or the like.
2) Geology: Mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable quantities in nature, as by the action of heat or water (Dictionary.com).

M.E. rokk(e), from O.Fr. ro(c)que, roche (cf. Sp., Provençal roca, It. rocca, M.L. rocca, V.L. *rocca, of uncertain origin.

Bard (Dehxodâ) "rock, stone," used in a large part of Western Iran, specifically in Lori and Kurd., related to Kurd. pal "rock, stone;" cf. Gk. poros "rock." Sang, → stone.

rock crystal
  بلور ِ سنگی، برد-بلور   
bolur-e sangi, bard-bolur

Fr.: cristal de roche   

Pure natural crystalline form of → silica, SiO2, which is transparent and colorless.

rock; → crystal.

rocket
  روکت   
roket

Fr.: fusée   

A projectile driven by reaction propulsion that carries its own propellants. → missile = mušak (موشک).

From It. rocchetto "a rocket," literally "a bobbin," diminutive of rocca "a distaff," with reference to its shape.

rocket astronomy
  اخترشناسی با روکت   
axtaršenâsi bâ roket

Fr.: astronomie par fusée   

The study of celestial bodies in the wavelengths that are almost completely absorbed by the atmosphere, by using a rocket to carry instruments above 250 km to measure the searched for phenomena.

rocket; → astronomy.

rocketry
  روکت‌شناسی، روکت‌گری   
roket šenâsi, roketgari

Fr.: fuséologie   

The science of rocket design, development, and flight.

rocket + -ry a noun suffix.

Roket šenâsi, from roket, → rocket, + šenâsi, → -logy; roketgari with suffix -gari, from -gar, → -or.

rockoon
  روکلون   
roklon

Fr.: fusée-sonde lancée à partir d'un ballon   

A rocket launched from a balloon at a pre-determined height and fired by a ground-controlled radio relay when some particular event, e.g. a solar flare, occurs.

From rocket + balloon.

From roket + lon, → ballon astronomy.

Roemer delay
  درنگ ِ رؤمر   
derang-e Rømer

Fr.: retard de Rømer   

A time delay caused by the light travel across a → dynamical system. The finite → speed of light causes a delay, for example, between the → primary eclipse and the → secondary eclipse in → binary systems.

Named after Ole Rømer (1664-1710), who discovered the finite speed of light, → Roemer's measurement; → delay.

Roemer's measurement
  اندازه‌گیری ِ رؤمر   
andâzegiri-ye Rømer

Fr.: mesure de Rømer   

The first successful measurement of the → speed of light carried out by the Danish astronomer Ole Rømer in 1675 at Paris Observatory. Astronomers knew that the mean period of revolution for Jupiter's innermost satellite → Io (Jupiter I) was 42.5 hours. During this period Io was sometimes eclipsed by Jupiter. Astronomers expected that if Io was visible at some time it must be visible 42.5 hours later. But Ole Rømer discovered that there were many irregularities in Io's orbital period. Sometimes Io appeared too early and other times too late in relation to the expected times. The irregularities repeated themselves precisely at a one-year interval, which meant that they must be connected to the Earth's rotation around the Sun. Rømer attributed this difference in time to the additional distance the light from Io had to travel at different times, and used this information to calculate the speed of light. He found that it takes light 22 minutes to traverse the Earth's orbital diameter; the correct figure was later determined to be 16 minutes and 40 seconds. Rømer was able to measure the speed of light to be 230,000 km s-1. Although this figure was very close to the currently accepted value of 300,000 km s-1, it was rejected by the scientific community of the time, who assumed it to be much too high a figure.

Ole Rømer (1664-1710); → measurement.

<< < -es -iv -ti 217 a- abe abs abs acc acc ach act act ada adi adv aff agg Alc Alf ali all alp alt Ama amp ana ang ang ann ano ant ant ape apo app aps arc arg arm art ass ast ast ast atm ato att aur aut axi B-t bai Bal bar bar Be bee Bes bi- bif bin bin bio bis bla bli blu Boe Bol bor bou bra bri Bro bum CAI cal Can cap car car cat cat CCD Cel cen CGS cha cha che che chr cir cir civ cla clo clo CMB 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 coo cor cor cor cos cos cos cou cov cra cri cro cry cum cur cyc d'A dar dat DC dea dec dec dec def def deh Del den dep des det dev dia dif dif dif dim dip dir dis dis dis dis dis div dom dou dou dri dup dus dyn dyn ear eas 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 fac fal far fec Fer fer fie fin fir fis fla flo flu fog for for Fou fra fre Fre Fro fus G-t gal gal Gam gas Gau Gem gen geo geo geo gia gla gol gra gra gra gra Gre Gre gui H a haf Hal har har He- hea hel Hel her Her hie hig his hom hor hot Hub Hug hur hyd hyd hyl hyp ice ide ima imp imp imp inc ind ind ine inf inf Inf inj InS ins int int int int int int int int inv inv ion iro Isl iso iso Jac jet jud jur Kel Kep kil kly L d Lag lam Lap lar lat law Lea len lep lib lig lin lin lin liq lit loc log lon Los low lum lun Lut Lyr mac mag mag mag mag mag maj man Mar mas mas mat mea mec mem mer mes met met met mic mid mil min Mir Miz mod mol mon moo MOS mul mul mut nai nas nat neb neg Neu neu New New Nih noi non non non nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove oxi pac Pal par par Par par pas Pau Pel per per per per per per pha phi pho pho pho phy pip Pla pla pla pla pla Plu Poi pol pol pol pop pos pos pot Pra pre pre pre Pri pri pri pro pro pro pro pro pro pro Pto pul puz 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 rev rhe Rie Rig Rit roe Ros rot Ruf Ryd Sag sam sat sca sca Sch Sco sec sec sec seg sel sem sen set sha SHB sho sib sie sil sim sin sit sky slo sno sod sol sol sol sol sor sou Spa spa spe spe spe sph spi Spi spr sta sta sta sta sta ste ste Ste sto str str sub sub sub suf sun sup sup sup sup sur swo syn sys tak Tay Tel ten ter tet the the the thi Tho thu tid tim toa top tot tra tra tra tra tri tri tro Tru tur twi Typ UBV ult unb uni uni uni up ura uti val var vec Vel ver ver vig vir vis VLT vol wad was wav wav wea wei Whe Wie win WN5 Wol X-r yea You zer zod > >>