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).
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.
The interplay between supersonic turbulence and self-gravity in star forming gas.
(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."
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.
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.
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.
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."
A thing that grazes.
Agent noun of → graze.
1) barmažandé; 2) barmaž
Fr.: 1) rasant; 2) rasage, frôlement, effleurement
Fr.: incidence rasante
Light striking a surface at an angle almost perpendicular to the normal. → grazing-incidence telescope.
Fr.: occultation rasante
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.
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."
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.
parhun-e bozorg, dâyere-ye ~
Fr.: grand cercle
A circle on a sphere whose plane passes through the center of the sphere.
Great Dark Spot
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 Red Spot
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.
greatest eastern elongation
bozorgtarin derâzeš-e xâvari
Fr.: plus grande élongation est
The Greatest → elongation of an inferior planet occurring after sunset.