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

A succession of → nuclear fissions when the neutrons released by previous fissions produce other nuclear fissions which themselves cause other reactions and the reactions goes on increasing exponentially.

→ chain; → reaction.

A high plateau site located at an altitude of 5,104 m in the Chilean Atacama desert, about 50 kilometers to the east of San Pedro de Atacama (longitude 67° 46' W, latitude 23° 02' S). It is the site of the → Atacama Large Millimeter Array.

In Kunza, the ancestral language of the people living in the region, Chajnantor or Tchacknatur means "lift-off place." It is the place of platforms for worshipping the Sun, where since immemorial time prayers and wishes lifted off (ESO book Cerca del Cielo).

A prefix meaning "copper," used in the formation of compound words.

From Gk. chalko-, combining form of chalkos "copper."

Xalco-, loan from Gk., as above.
Mes-, from mes, → copper.

→ chalcophile element.

→ chalco-; → -phile.

In the → Goldschmidt classification, a → chemical element that has an → affinity for sulphur, and therefore tending to be more abundant in sulphide minerals and ores than in other types of rock. This group is depleted in the silicate Earth and may be concentrated in the core. The group includes → silver (Ag), → arsenic (As), → bismuth (Bi), → cadmium (Cd), → copper (Cu), → mercury (Hg), → indium (In), → lead (Pb), → sulfur (S), → antimony (Sb), → selenium (Se), → tellurium (Te), and → thallium (Tl). As a consequence of their relatively low condensation temperatures (500-1100 K), most of these elements are depleted in terrestrial planets with respect to chondrites.

→ chalcophile; → element.

The Chameleon. A small inconspicuous → constellation in the southern hemisphere near → Crux, lying at approximate position: R.A. 11 h, Dec. -80°. Abbreviation: Cha; genitive form: Chamaeleonis;

From O.Fr. chaméléon, from L. chamaeleon, from Gk. khamaileon, from khamai "on the ground" (akin to chthon "earth;" cf. Av. zam- "the earth," Mid.Pers. zamig, Mod.Pers. zami, zamin "the earth," Skt. ksam, L. homo "earthly being" and humus "the earth," PIE *dh(e)ghom "earth") + leon "lion."

Âftâbparast "chameleon," literally "sun adorer," from âftâb "Sun, sunlight" + parast "worshipper,"

An enclosed space making part of a laboratory apparatus, such as → bubble chamber, → cloud chamber, → multiwire proportional chamber.

M.E., from O.Fr. chambre, from L.L. camera "a chamber, room."

Otâqak "small room, small chamber," cf. Sogdian ôtâk "place, region," ôtâkcik "local, regional, native" + -ak diminutive suffix.

Blowing out of → ionized gas from a → molecular cloud when the → ionization front of an → H II region created by an → embedded  → massive star arrives at the molecular cloud edge. The large → pressure gradient set up between the H II region and the → interstellar medium ejects the ionized material with velocities larger than 30 km/s, in a way comparable to champagne flowing out of a bottle.

From a hydrodynamical model first proposed by Guillermo Tenorio-Tagle (1979). Champagne, Fr., short for vin de Champagne "wine from Champagne," a historical region at northeast France, from L.L. campania "flat open country," from L. campus "field;" → effect.

The flow of → ionized gas escaping from a → molecular cloud due to the → champagne effect.

→ flow.

Small-scale variations in the position of the Earth's geographical poles within an irregular circle of 3 to 15 metres in diameter. It seems to result from two nearly circular components, a seasonal variation in the mass distribution on the Earth (ice, snow, atmosphere) and movements of matter within the Earth.

Named after Seth Carlo Chandler (1846-1913), the American astronomer who discovered the phenomenon; → wobble.

An astronomy satellite launched by NASA in 1999 July, specially designed to detect X-ray emission from very hot regions of the Universe such as exploded stars, clusters of galaxies, and matter around black holes. Chandra carries a high resolution mirror (aperture 1.2 m, focal length 10 m), two imaging detectors (HRC and ACIS), and two sets of transmission grating spectrometer (LETG and HETG). Important Chandra features are: an order of magnitude improvement in spatial resolution, good sensitivity from 0.1 to 10 keV, and the capability for high spectral resolution observations over most of this range. Chandra was initially given an expected lifetime of 5 years, but on 4 September 2001 NASA extended its lifetime to 10 years "based on the observatory's outstanding results." Among the results obtained using Chandra one can mention the spectacular image of the → supernova remnant Cassiopeia A. See also → X-ray astronomy.

Initially called Advanced X-ray Astrophysics Facility (AXAF), the satellite was renamed the Chandra X-ray Observatory in honor of Subrahmanyan Chandrasekhar, the 1983 Nobel Prize in Physics, → Chandrasekhar limit. Moreover, Chandra, or candra- means "moon" or "shining" in Skt., from cand- "to give light, shine;" cf. Gk. kandaros "coal;" L. candela "a light, torch," from candere "to shine;" → X-ray; → Observatory.

A limiting mass of about 1.44 Solar masses that the theory predicts a non-rotating → white dwarf can attain without collapsing to become a → neutron star or a → black hole. Over this → critical mass, the degeneracy pressure will be unable to bear the load of the bulk mass.

Named after Subrahmayan Chandrasekhar (1910-1995), Indian-born American astrophysicist who, with William A. Fowler, won the 1983 Nobel Prize for Physics for his research on white dwarfs; → limit.

1) (v.intr.) To undergo change.
2a) (v.tr.) To → alter, modify, or make different; to make to pass from one state to another; to → exchange.
2b) To transform or convert.
3) To substitute another or others for; exchange for something else, usually of the same kind.
4) The act of changing; alteration or variation of any kind. → adiabatic change, → canonical change, → polytropic change, → secular change, → exchange.

M.E., from O.Fr. changier, from L.L. cambiare, from L. cambire "to exchange, barter," of Celtic origin, cf. Breton kamm "curved, bent;" Gk. kampe "a corner, a joint;" L. campus "a field;" Lith. kampus "corner;" PIE *kamb- "to bend, crook."

Galnidan, variant of gardidan, gaštan "to change, to turn," → Universe, cf. Awromani gelnây, geln- "to turn over" (Cheung 2007).

1a) General: A condition or place of great disorder or confusion.
1b) Math., Physics: Highly disordered evolution of some → dynamical systems which is sensitively dependent on → initial conditions. In a → chaotic system the → aperiodic, → nonlinear evolution grows → exponentially with time. Ordinary chaos is not → turbulence, but turbulence is always chaotic.
2) In → astrogeology, a distinctive area of fractured terrain on a planet or satellite, e.g. Gorgonum Chaos located in the southern hemisphere of Mars.

Chaos, in Gk. mythology and cosmology, the void existing at the beginning of the creation, as evoked in Hesiod's (c. 850 B.C.) Theogony. However, the meaning of chaos, used by Hesiod, is a matter of debate. Some have interpreted it as the primeval absence of order (hence → confusion). Subsequently, the Roman writer Ovid (43 BC-17? AD) described Chaos in his Metamorphoses as an unordered and formless primordial mass, and opposed Chaos to Cosmos "the ordered universe."

Chaos "gaping void," from L. chaos, from Gk. khaos "abyss, that which gapes wide open, is vast and empty," from *khnwos, from PIE base *gheu-, *gh(e)i- "to gape."

1) Varšun, from Tabari varâšun, Gilaki varâšin, daršin, uršin all meaning "confused, unordered, untidy," cf. Qomi šur-o-šin "chaos, confusion". The stem šun-/šin- is related to Mod.Pers. šân- in afšândan, šândan "to disperse, scatter, stew" (Mid.Pers. afšândan "to spread, scatter"), Gilaki šondan "to disperse," Hamadani šuândan "to derange, disorder," Laki veršânâ "to disperse, scatter," Šuštari šayn "to shake, agitate," Kermâni owšin "a winnowing fork to separate chaff from the grain," Laki šovâné "scattered household furniture," Tabari timšan "sowing seeds;" all ultimately from Proto-Ir. *šan- "to shake;" see also → confuse. The prefix var-, variant bar- "up, over" (as well as dar- "in"), denotes "disorder, confusion" as in darham barham "upside-down, helter-skelter".
2) Šivâr "depression between two terrains," from Tabari; probably a variant of šiyâr, → groove.

The theory of unpredictable behavior that can arise in systems obeying deterministic scientific laws.

→ theory; → chaos.

Or, or relating to → chaos.

Chaotic, adj. from → chaos.

The behavior of a → chaotic system.

→ chaotic; → behavior.

A system that is → deterministic through → description by mathematical rules but can evolve highly → nonlinearly depending on → initial conditions. See also → chaos.

→ chaotic; → system.

The condition of being → chaotic.

→ chaotic; → -ity.

In → dark energy models, a hypothetical fluid that can lead to cosmic acceleration at late times. In its simplest form, the Chaplygin gas has the → equation of statep = - A/ρ, where p and ρ denote the → pressure and → energy density, respectively, and A is a positive model parameter. This equation was introduced by Chaplygin (1904, Sci. Mem. Moscow Univ. Math., 21) to study the lifting force on a plane wing in aerodynamics.

Named after Sergey Chaplygin (1869-1942), Russian physicist; → gas.