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: 13048 Search : far
dance
  ۱) وشت؛ ۲) وشتن، وشتیدن   
1) vašt (#); 2) vaštan (#), vaštidan

Fr.: 1) danse; 2) danser   

1a) A successive group of rhythmical steps or bodily motions, or both, usually executed to music.
1b) An act or round of dancing.
2a) To move one's feet or body, or both, rhythmically in a pattern of steps, especially to the accompaniment of music.
2b) To leap, skip, etc., as from excitement or emotion; move nimbly or quickly (Dictionary.com).

M.E. da(u)ncen "to dance," from O.Fr. dancier of unknown origin, perhaps related to O.H.G. *dansjan "to lead (someone) to a dance."

Vašt, variant of gašt, gardidan, gel, gelidan "to turn," → revolve, cf. Eastern Gilâni gilâr "dance."

dancer
  وشتار، وشتنده، وشتگر   
vaštâr, vaštande, vaštgar

Fr.: danseur, danseuse   

1) A person who dances.
2) A person who dances professionally, as on the stage (Dictionary.com).

dance; → -er.

Vaštâr, from vašt "dnace," + agent noun suffix -âr, as in parastâr, padidâr; vaštande, vaštgar with agent noun suffixes, -ande and -gar, → -or.

danger
  خطر   
xatar (#)

Fr.: danger   

1) Liability or exposure to harm or injury; risk; peril.
2) An instance or cause of peril; menace (Dictionary.com).

M.E. daunger, from O.Fr. dangier "power, power to harm, authority, control," alteration of dongier, from V.L. *dominarium "power of a lord," from L. dominus "lord, master," → domain.

Xatar "danger," loan from Ar.

Danjon astrolabe
  اسطرلاب ِ دانژون   
ostorlab-e Danjon

Fr.: astrolabe de Danjon   

A modern unportable astrolabe which is used for high precision measuring of stellar and geographical coordinates. The instrument uses the simultaneous observations of two images of the same star, one of the images formed directly by the lower face of a prism and the other by the light rays reflected first from a mercury bath and then by the upper face of the prism. The images coincide when the zenithal distance of the star attains a prefixed value (Gauss method of equal altitudes, → almucantar). Apart from astrometry, the Danjon astrolabe was used for studying the Earth's rotation and is currently used for solar radius measurements.

After André Danjon (1890-1967), French astronomer, who developed the instrument at the Strasbourg Observatory before the Second World War and at the Paris Observatory in 1948. The concept of prism astrolabe was initially invented by the French Auguste Claude (1858-1938) around 1900 and was later modified in collaboration with Ludovic Driencourt (1861-1940); → astrolabe.

Danjon scale
  مرپل ِ دانژون   
marpel-e danjon

Fr.: échelle de Danjon   

A scale to evaluate as exactly as possible the darkening degree of a total → lunar eclipse. The five steps of the scale run from 0 (extremely dark, invisible Moon) to 4 (extremely bright, the eclipse having a very weak effect on the Moon's visibility). The darkening at a lunar eclipse is determined to a great extent by the transparency of the terrestrial atmosphere, which is affected by clouds and the dust from the volcanic eruptions (M.S.: SDE).

Named after André Danjon, who set up the scale, → Danjon astrolabe; → scale.

dare
  ۱) درشیدن؛ ۲) درشه   
1) daršidan; 2) darše

Fr.: 1) oser; 2) défi   

1) To be courageous enough to try to do something.
2) A challenge, especially to prove courage.

M.E. durren, from O.E. durran "be bold enough, have courage" (to do something); cf. O.Norse dearr, O.H.G. giturran, Gothic gadaursan, from PIE root *dhers- "bold" source also of O.Pers. darš-, as below.

Daršidan, from O.Pers. darš- "to dare," Av. darš- (prefixed *upa- in upadarəš- "to dare"); cf. Khotanese darv- "to dare;" Baluci durrit/durr- "to take courage;" Skt. dhars "to venture;" Gk. thrasus "bold;" Goth. ga-daursan "to venture;" E. "to dare;" PIE *dhers- "to attack, venture, dare" (Cheung 2007).

daring
  درشمند   
daršmand

Fr.: audacieux   

Taking or willing to take risks; audaciousness.

dare; → -ing.

dark
  تاریک   
târik (#)

Fr.: sombre, obscur, noir   

Having very little or no light.

M.E. derk, O.E. deorc, from P.Gmc. *derkaz.

Târik, Mid.Pers. târig "dark," târ "darkness," Av. taθra- "darkness," taθrya- "dark," cf. Skt. támisrâ- "darkness, dark night," L. tenebrae "darkness," Hittite taš(u)uant- "blind," O.H.G. demar "twilight."

dark adaptation
  نیاوش به تاریکی   
niyâveš bé târiki

Fr.: adaptation à l'obscurité   

The automatic adjustment of the iris and retina of the eye to allow maximum vision in the dark, following exposure of the eye to a relatively brighter illumination.

dark; → adaptation.

dark cloud
  ابر ِ تاریک   
abr-e târik (#)

Fr.: nuage sombre   

A relatively dense cloud of → interstellar gas, mainly molecular, whose dust particles obscure the light of stars behind it. A famous example is the → Horsehead Nebula silhouetted against the reddish glow of the → H II region IC 434. Individual dark clouds come in a range of sizes from tens of → light-years to tiny → Bok globules of only a few thousands → astronomical units.

dark; → cloud.

dark current
  جریان ِ تاریکی   
jarayân-e târiki

Fr.: courant d'obscurité   

Current generated in an electronic detector by thermal effects, even in the absence of input signal. In a → CCD detector, the current rises from thermal energy within the silicon lattice comprising the CCD. These electrons are captured by the CCD's potential wells and counted as signal. → dark current noise.

dark; → current.

dark current noise
  نوفه‌ی ِ جریان ِ تاریکی   
nufe-ye jarayân-e târiki

Fr.: bruit du courant d'obscurité   

In a → CCD detector, statistical fluctuation of the → dark current, equal to the square root of the dark current. CCDs can be cooled either with thermoelectric coolers or liquid nitrogen to reduce this effect. Ideally, the dark current noise should be reduced to a point where its contribution is negligible over a typical exposure time.

dark; → current; → noise.

dark energy
  کاروژ ِ تاریک   
kâruž-e târik

Fr.: énergie noire   

A hypothetical form of energy that fills all the space and tends to increase the rate of expansion of the Universe. Assuming the existence of dark energy is a way to explain recent observations that the Universe appears to be expanding at an increasing rate (→ accelerating Universe). Dark energy seems to be a kind of anti-gravity force and is supposed to be related to → vacuum energy. Where gravity pulls things together at the more local level, dark energy tears them apart on the grander scale. The acceleration equation, one of Einstein's equations for the homogeneous Universe, indicates that if the Universe is accelerating, the pressure of the driving component should be strongly negative. The dark energy density relates to the → cosmological constant via: ρ&Lambda = Λc2/(8πG), where G is the → gravitational constant and c the → speed of light. The first indication of dark energy was provided by the observation of → Type Ia supernovae. Other probes of dark energy are: → baryon acoustic oscillations, → weak gravitational lensing, and clusters of galaxies. In the standard model of cosmology, dark energy currently accounts for almost 74% of the total mass-energy of the Universe. Two proposed forms for dark energy are the cosmological constant and exotic component such as → quintessence.

dark; → energy.

dark exposure
  اسنهش ِ تاریکی، نورداد ِ ~   
osneheš-e târiki, nurdâd-e ~

Fr.: pose d'obscurité   

A → CCD frame obtained with closed → shutters in the absence of any light source, in order to estimate the → dark current of the → detector.

dark; → exposure.

dark fringe
  فریز ِ تاریک   
fariz-e târik (#)

Fr.: frange noire   

One of the successive dark and light bands produced by diffraction or interference of light.

From O.Fr. frange, from V.L. *frimbia alteration by metathesis of L. fimbria "fringe, edge of garment."

Fariz, variants farviz, farâviz "fringe, edge of garment."

dark matter
  ماده‌ی ِ تاریک   
mâdde-ye târik (#)

Fr.: matière noire   

Matter that has no radiation and therefore cannot be detected directly, but whose presence can be inferred from dynamical phenomena produced by its gravitational influence. The existence of dark matter is deduced mainly from the rotational speeds of galaxies, velocities of galaxies in clusters, gravitational lensing by galaxy clusters, and the temperature distribution of hot gas in galaxies and clusters of galaxies. Dark matter plays also a central role in cosmic structure formation. There exists a large number of → non-baryonic dark matter candidates. They include, the hypothetical stable particles → WIMPs, → neutralinos, → axions, → gravitinos, etc. Among unstable candidates are gravitinos with mild R-parity violation and sterile neutrinos. See also → baryonic dark matter, → dark matter candidate.

The concept of dark matter was first introduced by J.H. Oort (1932, Bull. Astron. Inst. Netherlands, 6, 249), who studied the vertical motions of the stars in the solar neighborhood and found that the visible matter could account for at most 50% of the derived surface density. → dark; → matter.

dark matter annihilation
  نابودی ِ ماده‌ی ِ تاریک   
nâbudi-ye mâde-ye târik

Fr.: annihilation de la matière noire   

A hypothetical process whereby hypothetical → non-baryonic dark matter particles undergo → annihilation interactions with themselves. The process results in observable by-products such as high-energy photons, neutrinos, and other detectable particles. See also → dark matter decay.

dark; → matter; → annihilation.

dark matter candidate
  نامزد ِ ماده‌ی ِ تاریک   
nâmzad-e mâdde-ye târik (#)

Fr.: candidat matière noire   

A hypothetical physical entity capable of accounting for the corresponding observed phenomena involving → dark matter. → Non-baryonic dark matter candidates include → WIMPs, → neutralinos, → axions, → gravitinos. Among → baryonic dark matter candidates can be noted ordinary and heavy → neutrinos, clouds of → neutral hydrogen gas, and compact objects.

dark; → matter; → candidate.

dark matter decay
  تباهی ِ ماده‌ی ِ تاریک   
tabâhi-ye mâde-ye târik

Fr.: désintégration de la matière noire   

In theoretical models, the hypothetical transformation of a → non-baryonic dark matter particle when symmetry is violated at special physical conditions. Dark matter decay and → dark matter annihilation are expected to produce enormous amounts of energy in the form of gamma-rays, cosmic rays, etc.

dark; → matter; → decay.

dark matter halo
  هاله‌ی ِ ماده‌ی ِ تاریک   
hâle-ye mâde-ye târik (#)

Fr.: halo de matière sombre   

A vast region surrounding a galaxy where dynamical tracers reveal a large amount of → hidden mass. The halo has considerable mass but relatively low luminosity, suggesting the presence of a lot of → dark matter.

dark; → matter; → halo.

<< < -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 ave axi Bab bal Bal bar bar bea Bek 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 CH cha cha che Che chr cir cir cit 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 Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa 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 vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>