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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1223
centrifugal force
  نیروی ِ مرکزگریز   
niru-ye markaz-goriz (#)

Fr.: force centrifuge   

A force in a rotating reference frame directed outward from the axis of rotation.

centrifugal; → force.

centripetal
  مرکزگرا   
markaz-gerâ

Fr.: centripète   

Acting or moving toward a center or axis.

From Mod.L., coined 1687 by Sir Isaac Newton from L. centri- combining form of centrum "center" + petere "to fall, rush out;" cf. Av. pat- " to fly, fall, rush," Skt. patati "he flies, falls," Mid.Pers. patet "falls," opastan "to fall," Mod.Pers. oftâdan "to fall;" Gk. piptein "to fall," petomai "I fly;" PIE base *pet- "to fly, to rush."

Markaz-gerâ, from markaz, → center, + gerâ "inclining," from gerâyidan "to incline toward;" Mid.Pers. grâyitan, → diverge.

centripetal acceleration
  شتاب ِ مرکزگرا   
šetâb-e markaz-gerâ (#)

Fr.: accélération centripète   

The rate of change of the → tangential velocity of a body moving along a circular path. The direction of the centripetal acceleration is always inward along the radius vector of the circular motion. The magnitude of the centripetal acceleration is related to the tangential velocity and → angular velocity as follows: ω x ω x r = v2/r.

centripetal; → acceleration.

centripetal force
  نیروی ِ مرکزگرا   
niru-ye markaz-gerâ (#)

Fr.: force centripète   

The force exerted on a body moving in a circular path which is directed toward the center and keeps the body in motion.

centripetal; → force.

centroid
  مرکزوار   
markazvâr (#)

Fr.: centroïde   

Same as → center of gravity, → center of inertia, → center of mass, and → barycenter.

center + → -oid.

Cepheid
  کفیءوسی   
Kefeusi

Fr.: céphéide   

A class of luminous, → yellow supergiants that are pulsating variables and whose period of variation is a function of their luminosity. These stars expand and contract at extremely regular periods, in the range 1-50 days. Their highest brightness and surface temperature occur when their expansion velocity is greatest. Similarly, their minima in brightness and temperature occur when they are in the contraction phase. The longer the period, the more luminous the star. In fact, Cepheids provide one of the most powerful tools for measuring distances to other galaxies (→ period-luminosity relation). However, this method is limited to the distance of the → Virgo cluster of galaxies (15-20 → Mpc) even with the → HST or the largest ground-based telescopes. One particularly special Cepheid is the North Star, → Polaris.

Named after the prototype → Delta Cephei discovered by John Goodricke in 1784. → Cepheus.

Cepheid variable
  ورتنده‌ی ِ کفیءوسی   
vartande-ye Kefeusi

Fr.: variable Céphée   

A → variable star belonging to the class of → Cepheids.

Cepheid; → variable.

Cepheus
  کفیءوس   
Kefeus

Fr.: Céphée   

A → constellation in the Northern Hemisphere lying next to → Cassiopeia. It contains several pulsating variable stars, including the prototype → Cepheid variable Delta Cephei. Abbreviation: Cep, genitive: Cephei.

In Gk. mythology, Cepheus, king of Ethiopia, who was married to the beautiful → Cassiopeia, and was also father of princess → Andromeda.

Kefeus, from Gk. Cepheus. Arabicizd form qifâvus (قیفاووس).

Ceres
  سرس   
Seres (#)

Fr.: Cérès   

Once qualified as the largest known → asteroid, Ceres is now classified as a → dwarf planet (2006 IAU General Assembly). It is approximately 950 km across, and resides with tens of thousands of asteroids in the main → asteroid belt; it is the largest body of the belt. Its mass is 9.4 × 1020 kg, its → rotation period 9.074 hours, its → orbital period 4.60 years, and its → semi-major axis 2.767 AU. NASA's → Dawn spacecraft, which was placed in orbit around Ceres in 2015, has mapped its surface in great detail. Dawn discovered very bright spots, which reflect far more light than their much darker surroundings. The most prominent of these spots lie inside the crater → Occator and suggest that Ceres may be a much more active world than most of its asteroid neighbours (Molaro et al., 2015, arXiv:1602.03467).

Ceres in Roman mythology was the goddess of growing plants and of motherly love. She was equivalent to Demeter in Gk. mythology.

CERN
     
CERN

Fr.: Centre Européen pour la Recherche Nucléaire (CERN)   

European Organization for Nuclear Research, founded in 1954, and located on the Franco-Swiss border near Geneva, Switzerland. CERN is one of the world's largest centres for scientific research. At CERN, the world's largest and most complex scientific instruments are used to study the basic constituents of matter, i.e. the → elementary particles. The instruments used at CERN are particle → accelerators and → detectors. Currently it has 20 Member States.

CERN, acronym of the organization's original name Centre Européen pour la Recherche Nucléaire.

Cerro Tololo Inter-American Observatory (CTIO)
  نپاهشگاه ِ اندر-آمریکایی ِ کوه ِ تولولو   
Nepâhešgâh-e andar-Âmrikâyi-ye Kuh-e Tololo

Fr.: Observatoire inter-américain du Cerro Tololo   

A complex of astronomical telescopes and instruments located approximately 80 km to the East of La Serena, Chile, at an altitude of 2,200 m. CTIO headquarters are located in La Serena, Chile, about 480 km north of Santiago. The principal telescopes on site are the 4-m Victor M. Blanco Telescope and the 4.1-m Southern Astrophysical Research (SOAR) telescope. One of the two 8-m telescopes comprising the Gemini Observatory is co-located with CTIO on the Association of Universities for Research in Astronomy (AURA) property in Chile, together with more than 10 other telescopes and astronomical projects.

Cerro "mountain" in Spanish; Tololo a proper name; → inter-; American, from America, → North America Nebula; → Observatory.

certain
  تاشتیگ   
tâštig (#)

Fr.: certain   

Determined, fixed; established beyond doubt or question; indisputable. → determinism.

From O.Fr. certain, from V.L. *certanus, from L. certus "sure, fixed," originally a variant p.p. of cernere "to distinguish, decide."

Tâštig, from Mid.Pers. tâštig "certain," tâšitan "to cut, cleave, create," Mod.Pers. tarâšidan, Gilaki tâštan "to shave, scrape, cut," Av. taš- "to cut, fashion, shape, form," taša- "ax, hatchet," tašan- "creator, maker," cf. Skt. taks- "to cut, chop, form by cutting, make, create," taksan "carpenter," Gk. tekhne "art, skill, craft, method," L. textere "to weave;" PIE base *tek- "to shape, make."

certainty
  تاشتیگی   
tâštigi (#)

Fr.: certitude   

The fact, quality, or state of being certain, especially on the basis of evidence. Something that is certain. → uncertainty; → uncertainty principle.

Noun from → certain.

cesium
  سزیوم   
seziom (#)

Fr.: césium   

A soft ductile chemical element of the → alkali metal group; symbol Cs. It is found in several → silicate minerals, including pollucite. The metal oxidizes in air and reacts violently with water. → Atomic number 55; → atomic weight 132.9054; → melting point 28.4°C; → boiling point 669.3°C; → specific gravity 1.873 at 20°C; and → valence +1. Cesium has several radioactive isotopes, among which 134Cs with a half-life of 2.07 years and 137Cs with a half-life of 30.3 years. Cesium was discovered spectroscopically in 1860 by W. Bunsen and G. Kirchhoff in mineral water from Durkheim.

From L. caesius "bluish gray," which was the color of the cesium line in the spectroscope, + → -ium.

cesium clock
  ساعت ِ سزیوم   
sâ'at-e seziom

Fr.: horloge à cesium   

atomic fountain clock.

cesium; → clock.

Cetus
  کتوس   
Ketus

Fr.: Baleine   

The Whale, or Sea Monster. A large, rather inconspicuous → constellation in the equatorial region of the sky at R.A. 1h 30m, Dec. -10°. Its brightest star (Diphda) is a 2nd magnitude and contains → Mira Ceti, the first-known variable star, and the → Seyfert galaxy M77. Abbreviation: Cet; genitive form: Ceti.

Named after the sea monster in Gk. mythology sent by Poseidon to punish the Queen → Cassiopeia for bragging that she or her daughter → Andromeda was more beautiful than the Nereides. But → Perseus rescued Andromeda.

Ketus, from Gk., Arabicized form Qeytas (قیطس).

CGS system
  راژمان ِ CGS   
râžmân-e CGS

Fr.: système CGS   

The system of → CGS units.

CGS unit; → system.

CGS units
  یکاهای ِ س.گ.ث   
yekâhâ-ye CGS (#)

Fr.: unités CGS   

A → metric system of physical units based on → centimeter (length), → gram (mass), and → second (time).

CGS, the initials of → centimeter, → gram, and → second; meter, kilogram, and second; → unit.

CH (methylidine)
   CH (متیلیدین)   
CH (methylidine)

Fr.: CH (méthylidine)   

The first molecule detected in the interstellar medium. Methylidine radical (CH) was discovered by Walter S. Adams in 1937 using coudé spectroscopy in the direction of the bright star ζ Ophiuchi at the Mount Wilson Observatory (main CH line at 4300 Å).

Chemical term based on Gk. methy "wine," cognate with Pers. mey "wine," from Mid.Pers. mad, may "wine;" Av. maδu- "wine, mead;" cf. Skt. mádhu- "honey, wine, sweet drink," O.E. medu, E. mead, M.Du. mede, Ger. Met "mead;" O.C.S. medu, Lith. medus "honey;" Rus. m'od "honey," m'édved' "bear" (literally "honey-knower"); PIE base *médhu- "honey, sweet drink."

CH molecule
  مولکول ِ متیلیدین   
molekul-e methylidine

Fr.: molécule de méthylidine   

CH (methylidine).

CH (methylidine); → molecule.

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