An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1234

Fr.: chondrite   

The most common type of → meteorites containing → chondrules. These → stony meteorites make up about 86% of all meteorites. An important feature of the chondrites is that, with the exception of a few highly → volatile elements, they have the same composition as the Sun.

Chondrite, from chondr-, from chondros "grain", + suffix → -ite.


Fr.: chondrule   

Millimeter-sized grains of → silicate sometimes found in large numbers in → chondrite meteorites. They are essentially glassy beads made by a violent but brief heating event that caused dust grains to form melt droplets. However, the cause of the heating remains unknown.

From Gk. chondr-, from chondros "grain," + diminutive suffix → -ule.


Fr.: crave à bec rouge   

A member of the → crow family with a red beak and legs.

M.E. choghe; akin to O.E. ceo, Du. kauw, Dan. kaa.

Kalajik, from Daštak Baxtiyâri dialect, related to kal, kalâq, → crow.

Christoffel symbol
  نماد ِ کریستوفل   
namâd-e Christoffel (#)

Fr.: symbole de Christoffel   

A abbreviated notation for various functions associated with quadratic differential forms. Each Christoffel symbol is essentially a triplet of three indices, i, j and k, where each index can assume values from 1 to 2 for the case of two variables, or from 1 to n in the case of a quadratic form in n variables. Christoffel symbols appear in many calculations in geometry where non-Cartesian coordinates are used. These symbols are fundamental in the study of tensor analysis.

Named after Elwin Bruno Christoffel (1829-1900), a German mathematician; → symbol.

  رنگی، فامی   
rangi, fâmi

Fr.: chromatique   

Of or relating to color or color phenomena or sensations.

From L. chromaticus, from Gk. khromatikos "relating to color," from khroma, khromat- "color" + → -ic.

From rang, fâm, → chromo-, + -i adj. suffix.

chromatic aberration
  بیراهش ِ رنگی   
birâheš-e rangi

Fr.: aberration chromatique   

A defect in a lens that causes it to concentrate the various colors in a beam of light at various point, thus producing color fringes.

chromatic; → aberration.

krom (#)

Fr.: chrome   

A silver-gray, lustrous, brittle, hard metallic → chemical element that is resistant to tarnish and corrosion; symbol Cr. → Atomic number 24; → atomic weight 51.996; → melting point about 1,857°C; → boiling point about 2,672°C; → specific gravity about 7.2 at 20°C. Chromium is used in the hardening of steel alloys and the production of stainless steels. It is extracted by reducing the oxide with → aluminium. Its → radioactive isotope 51Cr has a half-life of 27.8 days. It was discovered in 1797 by the French chemist and pharmacist Nicolas-Louis Vauquelin (1763-1829).

From the Gk. chroma "color," from the many colored compounds of this element, + -ium a suffix used in the name of several chemical elements.

  رنگ-، فام-   
rang-, fâm-

Fr.: chromo-   

A prefix indicating "color, colored." Before a vowel: chrom-.

Combining form from Gk. chroma, khroma "color."

Rang, → color; fâm "color," probably related to bâm "light; morning light; splendor" (bâmdâd "morning,; splendor, light"); Mid.Pers. bâm "brillance, glory, splendor," bâmig "brilliant, glorious;" Av. bā- "to shine, appear, seem," (with ā-) auuā- "to have the appearance of, be like," (with fra-) frauuā- "to shine," (with ni-) -niuuā- "to radiate downward," (with ui-) viuuā- "to shine forth;" cf. Gk. phaos, phos "light," phainein "to show, to bring to light;" Skt. bhā- "to shine," bhati "shines, glitters," O.Ir. ban "white, light, ray of light."

  رنگ توانیک   

Fr.: chromodynamique   

A → quantum field theory of the → interaction of → quarks possessing a distinctive property called → color, in which the quarks exchange → gluons in a manner that is analogous to the interaction of → charged particles in → electrodynamics.

chromo-; → dynamics.

  فام‌سپهر، رنگین‌سپهر   
fâmsepehr (#), ranginsepehr (#)

Fr.: chromosphère   

A region of the stellar atmosphere situated above its → photosphere. The Sun's chromosphere extends from the about 500 km above the photosphere basis, up to 9,000 km, where it meets the → corona. For a plane-parallel model, the chromosphere is more or less continuous throughout the first 1,500 km, but breaks into indented spicules beyond that height. The chromosphere temperature grows from 4,400 K at 500 km to almost 6,000 K at 1,000-2,000 km. A rapid growth of coronal temperatures is registered at heights of about 2,500 km (the transition region), the exact height depending on the local magnetic field intensity. Actually, the chromosphere is made of rising and, often, falling jets called → spicules, which go up to 15,000 km. In the uppermost part of the chromosphere the density is the millionth part of its density at the base. Immediately before or after a solar → total eclipse, the chromosphere becomes visible either as a crescent or as a red → diamond ring, due to → H-alpha emission, from which it also gets its name. Moreover, the chromosphere can be seen in → H and K lines of calcium during eclipses, and in ultraviolet emission lines from space. The presence of the chromosphere around cold → dwarf stars is deduced from similar emissions (M.S.: SDE).

chromo- "color," because of the reddish-pink color of the chromosphere which is seen around the Sun during a total eclipse and is due to the dominance of the → H-alpha line; → sphere.


Fr.: chronographe   

A very accurate instrument that measures, indicates, or graphically records time intervals such as the duration of an event.

Chronograph, from Gk. khronos "time" + → -graph.

Gâhnegâr, from gâh "time" + negâr, → -graph.

  گاه‌شناسی، گاه‌راییک   
gâhšenâsi, gâhrâik

Fr.: chronologie   

The science of dating, of ordering time, of arranging in periods, and of determining temporal distances between past events.

Chronology, from Gk. khronos "time" + → -logy.

Gâhšenâsi, from gâh "time" + -šenâsi-logy. Gâhrâik, from gâh + rây, ârâ "order, arrangement" stem of ârâstan "to arrange, to set in order, adorn" (Mid.Pers. ârây-, ârâstan "to arrange, adorn," O.Pers. râs- "to be right, straight, true," râsta- "straight, true" (Mod.Pers. râst "straight, true"), râd- "to prepare," Av. râz- "to direct, put in line, set," Av. razan- "order," Gk. oregein "to stretch out," L. regere "to lead straight, guide, rule," p.p. rectus "right, straight," Skt. rji- "to make straight or right, arrange, decorate," PIE base *reg- "move in a straight line") + -ik-ics.

  گاه‌سنج، زمان‌سنج   
gâhsanj (#), zamânsanj (#)

Fr.: chronomètre   

A highly precise timepiece.

Chronometer, from from Gk. khronos "time" + → -meter.

Gâhsanj, zamânsanj, from gâh or zamân "time" + -sanj-meter.

  ۱) گویس؛ ۲) گویسیدن   
1) gavis; 2) gavisidan

Fr.: 1) baratte; 2) baratter   

1) A container or machine in which cream or milk is agitated to make butter.
2) To shake or agitate with violence or continued motion (

M.E. chirne, O.E. cyrne cyr(i)n; cognate with M.L.G. kerne, O.N. kjarni, kirna, may be related to → kernel because of the "grainy" appearance of churned cream.

Gavis "churn," of unknown origin.


Fr.: barattage   

In → galactic dynamics models, the process of gaining or losing → angular momentum by stars mostly at the → Lindblad resonances without gaining random motion. Figuratively, transient → spiral waves in → galactic disks churn the stars and gas in a manner that largely preserves the overall angular momentum distribution and leads to little increase in random motion. Churning is the main reason for → radial migration of stars. See also → blurring (J. A. Sellwood & J. J. Binney, 2002, astro-ph/0203510 and references therein).

Verbal noun of → churn.

CI chondrite
  کوندریت ِ IC   
kondrit-e CI

Fr.: chondrite CI   

A group of very rare → carbonaceous chondrites which are unusual because they do not have → chondrules. They are thought to be the most primitive of all meteorites. As a result of alteration, they lack chondrules and → CAIs, but contain up to 20% water, as well as various alteration minerals. Only five CI chondrite falls are known, and of these, only four are massive enough for multiple chemical analyses. The Orgueil meteorite is the most massive of CI chondrites.

C for → carbon, I stands for Ivuna meteorite that fell in Tanzania in 1938; → chondrite.

šangarf (#)

Fr.: cinabre   

A mineral, mercuric sulphide, HgS, which is the primary → ore for the production of → mercury. It is a → crystalline solid with a bright → red color. Cinnabar is highly toxic.

From O.Fr. cinabre, from L. cinnabaris, from Gk. kinnabari, maybe ultimately from Pers. šangarf "red lead, cinnabar," of unknown origin.


Fr.: circardien   

Being, having, characterized by, or occurring in approximately 24-hour periods or cycles, as of biological activity or function (

From L. circa "about," → circum-, + diem, accusative singular of dies "day," → diurnal.

circadian rhythm
  ریتم ِ پیراروزی   
ritm-e pirâruzi

Fr.: rythme circardien   

Any of several physical, mental and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in an organism's environment. Circadian rhythms are found in most living things, including animals, plants and many tiny microbes.

circadian; → rhythm.

Pargâr (#)

Fr.: Compas   

The Compasses. A small, faint → constellation in the southern hemisphere near → Musca and → Triangulum Australe, at about 15h right ascension and 60° south declination. Abbreviation: Cir; genitive Circini.

L. circinus "pair of compasses," from circus "circle, ring," from or akin to Gk. kirkos "a circle," from PIE *kirk- from base *(s)ker- "to turn, bend" (from which derives also Pers. carx "wheel, cycle," → cycle).

Pargâr, → compasses.

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