An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 430

Fr.: rasant   

A thing that grazes.

Agent noun of → graze.

  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.

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


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.

greatest eclipse
  بزرگترین خورگرفت   
bozogtarin xorgereft

Fr.: la plus grande éclipse   

The instant when the axis of the Moon's → shadow cone passes closest to Earth's center. For → total eclipses, the instant of greatest eclipse is virtually identical to the instants of greatest magnitude and greatest duration. However, for → annular eclipses, the instant of greatest duration may occur at either the time of greatest eclipse or near the sunrise and sunset points of the eclipse path (F. Espenak, NASA).

Superlative of → great; → eclipse.

greatest elongation
  بزرگترین درازش   
bozorgtarin derâzeš

Fr.: plus grande élongationt   

The largest → elongation of an inferior planet from the Sun. It may be → greatest eastern elongation or → greatest western elongation. The greatest elongation of Mercury is about 28°, and thus Mercury can only be observed 112 minutes after sunset or before sunrise. For Venus, it is about 47°, making it visible at most about 3 hours after sunset or before sunrise.

Superlative of → great; → eastern; → elongation.

greatest western elongation
  بزرگترین درازش ِ باختری   
bozorgtarin derâzeš-e bâxtari

Fr.: plus grande élongation ouest   

The Greatest → elongation of an inferior planet occurring before sunrise.

Superlative of → great; → western; → elongation.

Greek numeral system
  راژمان ِ عددهای ِ یونانی   
râžmân-e adadhâ-ye Yunâni

Fr.: numération grecque   

A → numeral system in which letters represent numbers. In an earlier system, called acrophonic, the symbols for numerals came from the first letter of the number name. Subsequently, the numerals were based on giving values to the letters of alphabet. For example α, β, γ, and δ represented 1, 2, 3, and 4; while ι, κ, λ, and μ stood for 10, 20, 30, and 40, and ρ, σ, τ, and υ for 100, 200, 300, and 400. The Greek also used the additive principle. For example 11, 12, 13, 14, and 374 were written ια, ιβ, ιγ, ιδ, and τοδ. The numbers between 1000 and 9000 were expressed by adding a subscript or superscript ι (iota) to the symbols for 1 to 9. For example ιA and ιΘ for 1000 and 9000. Numbers greater than 9999 were expressed using M, which was the myriad, 10,000. Therefore, since 123 was represented by ρκγ, 123,000 was written as Mρκγ.

numeral; → system.

sabz (#)

Fr.: vert   

A color intermediate in the spectrum between yellow and blue (wavelength between 5000 and 5700 Å). The color of most grasses and leaves while growing.

Green, from O.E. grene, related to growan "to grow," from W.Gmc. *gronja- (cf. Dan. grøn, Du. groen, Ger. grün), from PIE base *gro- "to grow."

Sabz "green," from Mid.Pers. sabz "green, fresh," related to sabzi "grass."

green flash
  درخش ِ سبز   
deraxš-e sabz (#)

Fr.: rayon vert   

A brilliant green color that occasionally appears on the upper limb of the Sun as it rises or sets.

green; → flash.

green pea
  نخود سبز   
noxod sabz

Fr.: petit pois   

A pea harvested and eaten while still green, soft, and unripe; a garden pea; usually in plural.

green; → pea.

Green Pea galaxy
  کهکشان ِ نخود سبز   
kahkešân-e noxod sabz

Fr.: galaxie petit pois   

A member of a class of galaxies of relatively small size (→ compact galaxy) having very strong → emission lines especially the → [O III] doublet and an unusually large → equivalent width of up to 1000 Å. They were first noted because of their peculiar bright green color and small size, unresolved in → Sloan Digital Sky Survey imaging. Green Peas are similar to high-→ redshift  → Lyman alpha emitting galaxies (LAEs) in many respects (small sizes, low → stellar masses, 108-10 → solar masses (Msun), low metallicities for their stellar masses, high → specific star formation rates (sSFR), and large [O III] λ5007/[O II]λ3727 ratios. Green Peas are relatively luminous and massive galaxies compared to the faint-end → dwarf starburst galaxies and LAEs (See Yang et al, 2017, arxiv/1706.02819, and references therein).

Such called because of their appearance and green color (mainly due to very strong optical emission line [O III] 5007 Å) in composite images; → green; → pea; → galaxy.

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