An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1251

Fr.: chiralité   

The geometric property of a rigid object that is → chiral.

chiral; → -ity.

Xeiron (#)

Fr.: Chiron   

An object, discovered in 1977, which was initially assumed to be an asteroid, but subsequent observations showed it to be a weak comet with a detectable coma. Its orbit, lying now between those of Saturn and Uranus, is unstable on time scales of a million years.

In Gk. mythology, Xειρων (Cheiron or Chiron) was the wisest of the Centaurs; he was not a drunkard like other Centaurs. Chiron was tutor to Jason and Heracles. He was the only immortal centaur.


Fr.: compression d'impulsion   

1) Telecommunications: A signal in which the wave frequency increases or decreases, linearly or exponentially, with time.
2) Astro: The theoretically predicted → gravitational wave arising from the interaction of two highly → compact objects. As the two objects spiral toward each other, due to orbital energy loss, the frequency and amplitude of the gravitational wave will increase continuously.

Chirp "a short, high-pitched sound, such as that made by certain birds or insects," from M.E. chirpen, of onomatopoeic origin.

Cirp loanword from E., as above.

Chladni pattern
  الگوی ِ کلادنی   
olgu-ye Chladni

Fr.: figure de Chladni   

A pattern formed by fine powder or salt placed on a vibrating surface. The figures display the positions of → nodes and → antinodes.

Named after Ernst Chladni (1756-1827), German physicist; → figure.

klorât (#)

Fr.: chlorate   

1) A negative ion, ClO3- derived from chloric acid.
2) Any salt of chloric acid.

From chlor-, → chlorine, + → -ate.

chloric acid
  اسید کلریک   
asid klorik (#)

Fr.: acide chlorique   

A colorless, strong acid HClO3, formed by the action of dilute sulfuric acid on barium chlorate.

From chlor-, → chlorine, + → -ic; → acid.

klor (#)

Fr.: chlore   

A gaseous → chemical element of the halogen group, which is greenish yellow and poisonous; symbol Cl. → Atomic number 17; → atomic weight 35.453; → melting point -100.98°C; → boiling point -34.6°C. Chlorine is about two and one-half times as dense as air. It is used for water purification, in the making of bleaching powder. Its compounds occur as common → salt (sodium chloride), NaCl, in sea water and as rock salt. Chlorine is the first poison gas to be used in warfare (by German army, the Second Battle of Ypres, 1915). It has several → radioactive isotopes, in particular 36Cl with a half-life of 3 × 105 years. Chlorine was discovered by the Swedish pharmacist and chemist Carl-Wilhelm Scheele (1742-1786) in 1774. In 1810, the English chemist Humphry Davy (1778-1829) proved it was an element and gave it the name chlorine.

From Gk. chloros "light green, greenish yellow;" cognate with Pers. zard "yellow," zarr "gold;" E. → gold, → yellow.


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.

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