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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


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Number of Results: 438
gravity wake
  کل ِ گرانی   
kel-e gerâni

Fr.: sillage de gravité   

Transient → streamers which form when → clumps of particles begin to collapse under their own → self-gravity but are sheared out by → differential rotation. This phenomenon is believed to be the source of → azimuthal asymmetry in → Saturn's → A ring (Ellis et al., 2007, Planetary Ring Systems, Springer).

gravity; → wake.

gravity wave
  موج ِ گرانی   
mowj-e gerâni

Fr.: onde de gravité   

1) A wave that forms and propagates at the free → surface of a body of → fluid after that surface has been disturbed and the fluid particles have been displaced from their original positions. The motion of such waves is controlled by the restoring force of gravity rather than by the surface tension of the fluid.
2) Not to be confounded with → gravitational wave.

gravity; → wave.

gravo-turbulence
  گرانی-آشوبناکی   
gerâni-âšubnâki

Fr.: gravo-turbulence   

The interplay between supersonic turbulence and self-gravity in star forming gas.

Gravo-, from grav-, from → gravity + epenthetic vowel -o- + → turbulence.

gray
  خاکستری   
xâkestari (#)

Fr.: gris   

(n.) A color between white and black. (adj.) Having a neutral hue.

M.E., O.E. græg, from P.Gmc. *græwyaz; cf. O.N. grar, O.Fris. gre, Du. graw, Ger. grau; Frank. *gris, Fr. gris.

Xâkestari, "ash-colored," from xâkestar "ashes," from Mid.Pers. *xâkâtur, from xâk "earth, dust" + âtur "fire," varaint âtaxš (Mod.Pers. âtaš, âzar, taš), from Av. ātar-, āθr- "fire," singular nominative ātarš-; O.Pers. ātar- "fire;" Av. āθaurvan- "fire priest;" Skt. átharvan- "fire priest;" cf. L. ater "black" ("blackened by fire"); Arm. airem "burns;" Serb. vatra "fire;" PIE base *āter- "fire."

gray (Gy)
  گری   
gray

Fr.: gray   

An SI unit of absorbed radiation dose. One gray is equivalent to an energy absorption of 1 → joule/kg. It has replaced the → rad (rd), an older standard. One gray is equivalent to 100 rad. See also → sievert (Sv).

Named for Louis Harold Gray (1905-1965), British radiologist and the pioneer of use of radiation in cancer treatment.

gray atmosphere
  جّو ِ خاکستری، هواسپهر ِ ~   
javv-e xâkestari, havâsepher-e ~

Fr.: atmosphère grise   

A simplifying assumption in the models of stellar atmosphere, according to which the absorption coefficient has the same value at all wavelengths.

gray; → atmosphere.

gray body
  جسم ِ خاکستری   
jesm-e xâkestari (#)

Fr.: corps gris   

A hypothetical body which emits radiation at each wavelength in a constant ratio, less than unity, to that emitted by a black body at the same temperature.

gray; → body.

graze
  برمژیدن   
barmažidan (#)

Fr.: raser, frôler, effleurer   

To touch or rub lightly in passing.

Perhaps special use of graze "to feed on grass," from M.E. grasen, O.E. grasian.

Barmažidan, from Choresmian parmž "to touch, to rub," variants barmajidan, majidan, parmâsidan, Mid.Pers. pahrmâh- "to touch, to feel;" ultimately from Proto-Ir. *pari-mars-, from *Hmars-, *Hmarz- "to touch, rub, wipe;" probably related to marz "border, frontier," mâlidan "to rub, polish."

grazer
  برمژنده   
barmžandé

Fr.: rasant   

A thing that grazes.

Agent noun of → graze.

grazing
  ۱) برمژنده؛ ۲) برمژ   
1) barmažandé; 2) barmaž

Fr.: 1) rasant; 2) rasage, frôlement, effleurement   

1) Describing something that grazes. → grazing angle, → grazing occultation.
2) The act of touching or rubbing lightly in passing.

graze; → -ing.

grazing incidence
  فتاد ِ برمژنده   
fotâd-e barmažandé

Fr.: incidence rasante   

Light striking a surface at an angle almost perpendicular to the normal. → grazing-incidence telescope.

grazing; → incidence.

grazing occultation
  فروپوشانش ِ برمژنده   
forupušâneš-e barmažandé

Fr.: occultation rasante   

A special type of occultation that occurs when the star appears to pass tangentially on the → edge of the → Moon.

grazing; → occultation.

grazing-incidence telescope
  تلسکوپ با فتاد ِ برمژنده   
teleskop bâ fotâd-e barmažandé

Fr.: télescope à incidence rasante   

A telescope design used for focusing → extreme ultraviolet, → X-rays, and → gamma rays by means of → grazing incidence. Such short wavelengths do not reflect in the same manner as at the large incidence angles employed in optical and radio telescopes. Instead, they are mostly absorbed. To bring X-rays to a → focus, one has to use a different approach from → Cassegrain or other typical → reflecting telescopes. In a grazing-incidence telescope, incoming light is almost → parallel to the → mirror surface and strikes the mirror → surface at a very → shallow angle. Much like skipping a stone on the water by throwing it at a low angle to the surface, X-rays may be → deflected by mirrors arranged at low incidence angles to the incoming energy. Several designs of grazing-incidence mirrors have been used in various → X-ray telescopes, including → plane mirrors or combinations of → parabolic and → hyperbolic surfaces. To increase the collecting area a number of mirror elements are often nested inside one another. For example, the → Chandra X-ray Observatory uses two sets of four nested grazing-incidence mirrors to bring X-ray photons to focus onto two → detector instruments. → Bragg's law; → X-ray astronomy.

grazing incidence; → telescope.

great
  بزرگ   
bozorg (#)

Fr.: grand   

Unusual or considerable in degree, power, intensity, number, etc.

O.E. great "big, coarse, stout," from W.Gmc. *grautaz (cf. Du. groot, Ger. groß "great").

Bozorg "great, large, immense, grand, magnificient;" Mid.Pers. vazurg "great, big, high, lofty;" O.Pers. vazarka- "great;" Av. vazra- "club, mace" (Mod.Pers. gorz "mace"); cf. Skt. vájra- "(Indra's) thunderbolt," vaja- "strength, speed;" L. vigere "be lively, thrive," velox "fast, lively," vegere "to enliven," vigil "watchful, awake;" P.Gmc. *waken (Du. waken; O.H.G. wahhen; Ger. wachen "to be awake;" E. wake); PIE base *weg- "to be strong, be lively."

Great Attractor
  درکشنده‌ی ِ بزرگ   
darkašande-ye bozorg

Fr.: Grand Attracteur   

A hypothesized large concentration of mass (about 1016  → solar masses), some hundred million → light-years from Earth, in the direction of the → Centaurus → supercluster, that seems to be affecting the motions of many nearby galaxies by virtue of its gravity.

great; → attractor.

great circle
  پرهون ِ بزرگ، دایره‌ی ِ ~   
parhun-e bozorg, dâyere-ye ~

Fr.: grand cercle   

A circle on a sphere whose plane passes through the center of the sphere.

great; → circle.

Great Dark Spot
  لکه‌ی ِ سیاه ِ بزرگ   
lake-ye siyâh-e bozorg

Fr.: Grande tache noire   

One of a series of dark spots on → Neptune similar in appearance to Jupiter's → Great Red Spot. It was discovered in 1989 by NASA's Voyager 2 space probe. Also known as GDS-89. The dark, oval spot had initial dimensions of 13,000 × 6,600 km, about the same size as Earth. Although it appears similar to Jupiter's spot, which is an → anticyclonic storm, it is believed that the Great Dark Spot is an atmospheric hole similar to the hole in Earth's → ozone layer ozone layer. Moreover, unlike Jupiter's spot, which has lasted for hundreds of years, the lifetimes of Great Dark Spots appear to be much shorter, forming and disappearing once every few years or so. Based on pictures taken by Voyager and since then with the → Hubble Space Telescope, Neptune appears to spend somewhat more than half its time with a Great Dark Spot. Around the Great Dark Spot, winds were measured blowing up to 2,400 km an hour, the fastest in the solar system.

great; → dark; → spot.

Great Red Spot
  لکه‌ی ِ سرخ ِ بزرگ   
lakke-ye sorx-e bozorg (#)

Fr.: Grande tache rouge   

An anticyclonic storm on the planet Jupiter akin to a hurricane on Earth, but it is enormous (three Earths would fit within its boundaries) and it has persisted for at least the 400 years that humans have observed it through telescopes.

great; → red; → spot.

Great Rift
  چاک ِ بزرگ   
câk-e bozorg

Fr.:   

An apparent fissure in the bright clouds of the Milky Way between → Cygnus and → Sagittarius caused by a series of large, dark, overlapping clouds.

great; → rift.

greatest eastern elongation
  بزرگترین درازش ِ خاوری   
bozorgtarin derâzeš-e xâvari

Fr.: plus grande élongation est   

The Greatest → elongation of an inferior planet occurring after sunset.

Superlative of → great; → eastern; → elongation.


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