# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13176 Search : in
 centripetal   مرکزگرا   markaz-gerâFr.: centripète   Acting or moving toward a → center or → axis. → centripetal acceleration, → centripetal force.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 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 (v) and → angular velocity (ω) as follows: ac = v2/r = rω2. According to → Newton's second law, an object undergoing centripetal acceleration is experiencing a → centripetal force. centripetal force   نیروی ِ مرکزگرا   niru-ye markaz-gerâ (#)Fr.: force centripète   The force exerted on an object in → circular motion which is directed toward the center and keeps the body in motion. Centripetal force produces → centripetal acceleration, according to → Newton's second law: Fc = mac. Its direction is always inward along the → radius vector, and its magnitude is given by: Fc= mac = mvt2/r = mω2r.→ centripetal; → force. centroid   مرکزوار   markazvâr (#)Fr.: centroïde   1) Same as → center of gravity, → center of inertia, → center of mass, and → barycenter. 2) In a triangle, the point where the three medians converge.→ center + → -oid. Cepheid   کفیءوسی   KefeusiFr.: 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. The process that drives the pulsation of → Cepheid variables is the → kappa mechanism. 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. See also → RR Lyrae star.Named after the prototype → Delta Cephei discovered by John Goodricke in 1784. → Cepheus. Cepheid variable   ورتنده‌ی ِ کفیءوسی   vartande-ye KefeusiFr.: variable Céphée   A → variable star belonging to the class of → Cepheids.→ Cepheid; → variable. Cepheus   کفیءوس   KefeusFr.: 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 from a distance. Dawn caught sight of bright spots that soon resolved into more than 130 bright patches, most of them tied to craters. The most prominent of these spots lie inside the crater → Occator. The patches turned out to be carbonate salts, which only form in the presence of water. Since water skips to gas almost immediately on the dwarf planet's surface, the discovery of carbonates suggested that there was liquid beneath the dwarf planet's crust. Aside from craters, the only outstanding feature On Ceres is a single mountain, Ahuna Mons. It formed about 250 million years ago when plumes of saltwater and mud rose and erupted from within Ceres.Ceres in Roman mythology was the goddess of growing plants and of motherly love. She was equivalent to Demeter in Gk. mythology. CERN      CERNFr.: 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 TololoFr.: 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 seziomFr.: horloge à cesium   → cesium; → clock. Cetus   کتوس   KetusFr.: 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 CGSFr.: 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 methylidineFr.: molécule de méthylidine chain   زنجیر، زنجیره   zanjir (#), zanjiré (#)Fr.: chaîne   1) A series of usually metal links passing through one another, used for various purposes. 2) A series of things connected or following in succession. → chain reaction; → proton-proton chain.Chain, from O.Fr. chaeine, from L. catena "fetter."Zanjir from Mid.Pers. zanjir "chain;" zanjiré, from zanjir + nuance suffix -é.