An Etymological Dictionary of Astronomy and Astrophysics

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).

See also: 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.”

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).

See also: 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 (methylidine).

See also: → CH (methylidine); → molecule.

→ CH (methylidine).

See also: → CH (methylidine); → molecule.

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.

Etymology (EN): Chain, from O.Fr. chaeine, from L. catena “fetter.”

Etymology (PE): Zanjir from Mid.Pers. zanjir “chain;” zanjiré, from zanjir + nuance suffix -é.

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.

Etymology (EN): Chain, from O.Fr. chaeine, from L. catena “fetter.”

Etymology (PE): Zanjir from Mid.Pers. zanjir “chain;” zanjiré, from zanjir + nuance suffix -é.

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.

See also: → chain; → reaction.

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.

See also: → 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.

See also: 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 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.

See also: 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.

Etymology (EN): From Gk. chalko-, combining form of chalkos “copper.”

Etymology (PE): Xalco-, loan from Gk., as above.
Mes-, from mes, → copper.

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

Etymology (EN): From Gk. chalko-, combining form of chalkos “copper.”

Etymology (PE): Xalco-, loan from Gk., as above.
Mes-, from mes, → copper.

→ chalcophile element.

See also: → chalco-; → -phile.

→ chalcophile element.

See also: → 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.

See also: → chalcophile; → element.

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.

See also: → 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;

Etymology (EN): 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.”

Etymology (PE): Âftâbparast “chameleon,” literally “sun adorer,” from âftâb “Sun, sunlight” + parast “worshipper,”

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;

Etymology (EN): 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.”

Etymology (PE): 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.

Etymology (EN): M.E., from O.Fr. chambre, from L.L. camera “a chamber, room.”

Etymology (PE): Otâqak “small room, small chamber,” cf. Sogdian ôtâk “place, region,” ôtâkcik “local, regional, native” + -ak diminutive suffix.

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

Etymology (EN): M.E., from O.Fr. chambre, from L.L. camera “a chamber, room.”

Etymology (PE): 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.

Etymology (EN): 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.

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.

Etymology (EN): 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.

See also: → flow.

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

See also: → 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.

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

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.

See also: 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.

See also: 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.

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.

See also: 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.

Etymology (EN): 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.

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.

Etymology (EN): 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.

Etymology (EN): 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.”

Etymology (PE): Galnidan, variant of gardidan, gaštan “to change, to turn,” → Universe, cf. Awromani gelnây, geln- “to turn over” (Cheung 2007).

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.

Etymology (EN): 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.”

Etymology (PE): 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.

Etymology (EN): 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.”

Etymology (PE): 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.

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.

Etymology (EN): 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.”

Etymology (PE): 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.

See also: → theory; → chaos.

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

See also: → theory; → chaos.

Or, or relating to → chaos.

See also: Chaotic, adj. from → chaos.

Or, or relating to → chaos.

See also: Chaotic, adj. from → chaos.

The behavior of a → chaotic system.

See also: → chaotic; → behavior.

The behavior of a → chaotic system.

See also: → chaotic; → behavior.

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

See also: → chaotic; → system.

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

See also: → chaotic; → system.

The condition of being → chaotic.

See also: → chaotic; → -ity.

The condition of being → chaotic.

See also: → 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.

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

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.

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

A band in the → absorption spectrum of → ozone (O₃) extending in the → visible from 400 nm to 700 nm. → Hartley band, → Huggins band.

See also: J. Chappuis, Acad. Sci., Paris, C. R. 91, 985 (1880).

A band in the → absorption spectrum of → ozone (O₃) extending in the → visible from 400 nm to 700 nm. → Hartley band, → Huggins band.

See also: J. Chappuis, Acad. Sci., Paris, C. R. 91, 985 (1880).

1a) The aggregate of features and traits that form the individual nature of some person or thing.

1b) One such feature or trait; characteristic.

2. A person represented in a play, film, story, etc; role. See also
   → personage (Dictionary.com).
   

3. Computers: One of a set of symbols, such as letters or numbers, that are arranged to express information; the numerical code representing such a character.

Etymology (EN): M.E. carecter “distinctive mark,” from O.Fr. caractère, from L. character, from Gk. kharakter “graving tool, its mark,” from kharassein “to engrave,” from kharax “pointed stick.”

Etymology (PE): 1, 2) Serešt “nature, temperament, constitution; mixed,” sereštan “to mix, mingle; knead;” serišom “glue;” Mid.Pers. srištan “to mix, knead;” cf. Av. ham-sriš- “to put together;” Skt. śres- “to cling, stick, be attached;” Proto-Ir. root *sraiš- “to put together, attach” (Cheung 2007).
Sereštâr with -âr, contraction of âvar agent noun of âvardan “to bring; to cause, produce,” → format.

3. Daxšé, variants dâq “a brand, a mark burned on the skin of an
   animal with a hot iron,” Gilaki dajé “a brand,”
   Hamadani daj “sign placed on a heap of harvest indicating identity or ownership,” Mid.Pers. daxšag “mark, sign, charactersitic; (monthly) signs (of women)”, dazidan “to burn, scorch,” Av. daxša-
   “sign, mark, defect,” from dag- “to burn,” dažaiti “burns,” cf. Skt. dah- “to burn,” dahati “burns,” Gk. tephra “ash,” L. favilla “glowing ashes,” Lith. dagas “hot season,” O.Prus. dagis “summer,” P.Gmc. *dagaz, Ger. Tag, E. day; PIE *dheg^wh- “to burn.”

1a) The aggregate of features and traits that form the individual nature of some person or thing.

1b) One such feature or trait; characteristic.

2. A person represented in a play, film, story, etc; role. See also
   → personage (Dictionary.com).
   

3. Computers: One of a set of symbols, such as letters or numbers, that are arranged to express information; the numerical code representing such a character.

Etymology (EN): M.E. carecter “distinctive mark,” from O.Fr. caractère, from L. character, from Gk. kharakter “graving tool, its mark,” from kharassein “to engrave,” from kharax “pointed stick.”

Etymology (PE): 1, 2) Serešt “nature, temperament, constitution; mixed,” sereštan “to mix, mingle; knead;” serišom “glue;” Mid.Pers. srištan “to mix, knead;” cf. Av. ham-sriš- “to put together;” Skt. śres- “to cling, stick, be attached;” Proto-Ir. root *sraiš- “to put together, attach” (Cheung 2007).
Sereštâr with -âr, contraction of âvar agent noun of âvardan “to bring; to cause, produce,” → format.

3. Daxšé, variants dâq “a brand, a mark burned on the skin of an
   animal with a hot iron,” Gilaki dajé “a brand,”
   Hamadani daj “sign placed on a heap of harvest indicating identity or ownership,” Mid.Pers. daxšag “mark, sign, charactersitic; (monthly) signs (of women)”, dazidan “to burn, scorch,” Av. daxša-
   “sign, mark, defect,” from dag- “to burn,” dažaiti “burns,” cf. Skt. dah- “to burn,” dahati “burns,” Gk. tephra “ash,” L. favilla “glowing ashes,” Lith. dagas “hot season,” O.Prus. dagis “summer,” P.Gmc. *dagaz, Ger. Tag, E. day; PIE *dheg^wh- “to burn.”

1a ) A distinguishing feature or quality.

1b) The integer part of a → common logarithm.

For example, log₁₀ (23) = 1.362, where the characteristic is 1 and the → mantissa is 0.362.

2) Pertaining to, constituting, or indicating the character or

peculiar quality of a person or thing; typical; distinctive.

See also: → character; → -istic.

1a ) A distinguishing feature or quality.

1b) The integer part of a → common logarithm.

For example, log₁₀ (23) = 1.362, where the characteristic is 1 and the → mantissa is 0.362.

2) Pertaining to, constituting, or indicating the character or

peculiar quality of a person or thing; typical; distinctive.

See also: → character; → -istic.

Of a pulsar, a normalized period of rotation assumed to be a good approximation to pulsar’s true age.

See also: → characteristic; → age.

Of a pulsar, a normalized period of rotation assumed to be a good approximation to pulsar’s true age.

See also: → characteristic; → age.

Graph representing an optical film’s response to the amount of light falling on it.

See also: → characteristic; → curve.

Graph representing an optical film’s response to the amount of light falling on it.

See also: → characteristic; → curve.

Physics: An analytical relationship between a set of physical variables that determines the state of a physical system.
Math.: The equation which is solved to find a matrix’s eigenvalues, also called the characteristic polynomial.

See also: → characteristic; → equation.

Physics: An analytical relationship between a set of physical variables that determines the state of a physical system.
Math.: The equation which is solved to find a matrix’s eigenvalues, also called the characteristic polynomial.

See also: → characteristic; → equation.

A typical or most likely mass for the formation of an astronomical object. In current star formation models, it is of order of a few tenths of a → solar mass.

See also: → characteristic; → mass.

A typical or most likely mass for the formation of an astronomical object. In current star formation models, it is of order of a few tenths of a → solar mass.

See also: → characteristic; → mass.

The quantity kT in the → Maxwell-Boltzmann distribution law, where k is → Boltzmann’s constant and T the gas temperature. See also → thermal energy.

See also: → characteristic; → thermal; → energy

The quantity kT in the → Maxwell-Boltzmann distribution law, where k is → Boltzmann’s constant and T the gas temperature. See also → thermal energy.

See also: → characteristic; → thermal; → energy

1. The act of describing the character or qualities of someone or something.
   

2. The artistic representation (as in fiction or drama) of human character or motives (Merriam-Webster.com).

See also: → characterize; → -tion.

1. The act of describing the character or qualities of someone or something.
   

2. The artistic representation (as in fiction or drama) of human character or motives (Merriam-Webster.com).

See also: → characterize; → -tion.

1. To mark or distinguish as a characteristic; be a characteristic of.
   

2. To describe the character or individual quality of.
   

3. To attribute character to (Dictionary.com).

See also: → character; → -ize.

1. To mark or distinguish as a characteristic; be a characteristic of.
   

2. To describe the character or individual quality of.
   

3. To attribute character to (Dictionary.com).

See also: → character; → -ize.

A black amorphous substance produced by heating wood or other natural organic matter
in the absence of air. It is used as a fuel.

Etymology (EN): M.E. charcole, maybe from cherre “char” + cole, → coal.

Etymology (PE): Zoqâl “live coal, charcoal,” variant sokâr; Sogd. askâr; Pashto skor-; Khotanese skara, probably ultimately from Proto-Ir. *uz-gar-, from *uz- “out,” → ex-, + *gar “to heat, kindle fire, cook;” cf. Tabari kalə “furnace,” kəlen “ash;” Laki koira; Kurd. kulan, kulandan “to cook;”
related to garm “warm;” cf. Skt. ghar- “to burn,” PIE root *gwher- “to warm, be warm,” → warm.

A black amorphous substance produced by heating wood or other natural organic matter
in the absence of air. It is used as a fuel.

Etymology (EN): M.E. charcole, maybe from cherre “char” + cole, → coal.

Etymology (PE): Zoqâl “live coal, charcoal,” variant sokâr; Sogd. askâr; Pashto skor-; Khotanese skara, probably ultimately from Proto-Ir. *uz-gar-, from *uz- “out,” → ex-, + *gar “to heat, kindle fire, cook;” cf. Tabari kalə “furnace,” kəlen “ash;” Laki koira; Kurd. kulan, kulandan “to cook;”
related to garm “warm;” cf. Skt. ghar- “to burn,” PIE root *gwher- “to warm, be warm,” → warm.

→ electric charge.

Etymology (EN): Charge from O.Fr. chargier “load, burden,” from L.L. carricare “to load a wagon, cart,” from L. carrus “wagon.”

Etymology (PE): Bâr “charge, weight,” from Mid.Pers. bâr,
from O.Pers./Av. base bar- “to bear, carry,” Mod.Pers. bordan “to carry,” L. brutus “heavy, dull, stupid, brutish,” Skt. bhara- “burden, load,” bharati “he carries,” Gk. baros “weight,” Mod.Pers. gerân “heavy,” Skt. guru, L. gravis; PIE *gwere- “heavy,” *bher- “carry, give birth.”

→ electric charge.

Etymology (EN): Charge from O.Fr. chargier “load, burden,” from L.L. carricare “to load a wagon, cart,” from L. carrus “wagon.”

Etymology (PE): Bâr “charge, weight,” from Mid.Pers. bâr,
from O.Pers./Av. base bar- “to bear, carry,” Mod.Pers. bordan “to carry,” L. brutus “heavy, dull, stupid, brutish,” Skt. bhara- “burden, load,” bharati “he carries,” Gk. baros “weight,” Mod.Pers. gerân “heavy,” Skt. guru, L. gravis; PIE *gwere- “heavy,” *bher- “carry, give birth.”

The heavy saturation of CCD pixels whereby electrons spill over up and down the column; also called blooming.

Etymology (EN): → chrge; bleeding, from Bleed, from O.E. bledan, from P.Gmc. *blothjan “emit blood” (cf. Ger. bluten), from *blotham “blood”, PIE root bhel- “to bloom, thirve”.

Etymology (PE): Sarriz “overflow”, from sar “head”
(Mid.Pers. sar, Av. sarah- “head,” Skt. siras- “head,” Gk. kara “head,” keras “horn,” Mod.Pers. sarun “horn,” L. cerebrum “brain;” PIE *ker- “head, horn”) + riz present stem of rixtan “to pour; to flow; to cast” (Mid.Pers. rēxtan and rēcitan “to flow,” Av. raēk- “to leave, set free; to yield, transfer,” infinitive *ricyā, Mod.Pers; rig in morderig “heritage” (literally, “left by the dead”), Skt. rinakti “he leaves,” riti- “stream; motion, course,” L. rivus “stream, brook,” Old Church Slavic rēka “river,” Rus. reka “river,” Goth. rinnan “run, flow,” rinno “brook,” O.E. ridh “stream;” PIE base *rei- “to flow; to run”).

The heavy saturation of CCD pixels whereby electrons spill over up and down the column; also called blooming.

Etymology (EN): → chrge; bleeding, from Bleed, from O.E. bledan, from P.Gmc. *blothjan “emit blood” (cf. Ger. bluten), from *blotham “blood”, PIE root bhel- “to bloom, thirve”.

Etymology (PE): Sarriz “overflow”, from sar “head”
(Mid.Pers. sar, Av. sarah- “head,” Skt. siras- “head,” Gk. kara “head,” keras “horn,” Mod.Pers. sarun “horn,” L. cerebrum “brain;” PIE *ker- “head, horn”) + riz present stem of rixtan “to pour; to flow; to cast” (Mid.Pers. rēxtan and rēcitan “to flow,” Av. raēk- “to leave, set free; to yield, transfer,” infinitive *ricyā, Mod.Pers; rig in morderig “heritage” (literally, “left by the dead”), Skt. rinakti “he leaves,” riti- “stream; motion, course,” L. rivus “stream, brook,” Old Church Slavic rēka “river,” Rus. reka “river,” Goth. rinnan “run, flow,” rinno “brook,” O.E. ridh “stream;” PIE base *rei- “to flow; to run”).

A mobile particle carrying an electric charge. In semiconductors, a mobile electron or hole. Also called carrier.

See also: → charge; → carrier.

A mobile particle carrying an electric charge. In semiconductors, a mobile electron or hole. Also called carrier.

See also: → charge; → carrier.

In particle physics, an operation that changes a particle to its antiparticle in equations describing subatomic particles or, equivalently, reverses its charge and magnetic moment.

See also: → charge; → conjugation.

In particle physics, an operation that changes a particle to its antiparticle in equations describing subatomic particles or, equivalently, reverses its charge and magnetic moment.

See also: → charge; → conjugation.

The → electric charge per unit volume in space, or per unit area on a surface, or per unit length of a line. They are respectively called volume- (ρ), surface- (σ), or line (λ) charge density.

See also: → charge; → density.

The → electric charge per unit volume in space, or per unit area on a surface, or per unit length of a line. They are respectively called volume- (ρ), surface- (σ), or line (λ) charge density.

See also: → charge; → density.

The way a number of → electric charges are arranged in space with respect to the point of observation.

See also: → charge; → distribution.

The way a number of → electric charges are arranged in space with respect to the point of observation.

See also: → charge; → distribution.

A collisional process in which an → ion collides with a neutral → atom or → molecule and captures one of its electrons. One of the most important charge-exchange processes occurring in the → interstellar medium is: O⁺ + H → H⁺ + O + 0.020 eV.

See also: → charge; → exchange.

A collisional process in which an → ion collides with a neutral → atom or → molecule and captures one of its electrons. One of the most important charge-exchange processes occurring in the → interstellar medium is: O⁺ + H → H⁺ + O + 0.020 eV.

See also: → charge; → exchange.

The → electric charge carried by an object is independent of the → velocity of the object with respect to the → observer. In other words, the charge is the same in any → frame of reference.

See also: → charge; → invariance.

The → electric charge carried by an object is independent of the → velocity of the object with respect to the → observer. In other words, the charge is the same in any → frame of reference.

See also: → charge; → invariance.

Same as → charge conjugation and → C-symmetry.

See also: → charge; → symmetry.

Same as → charge conjugation and → C-symmetry.

See also: → charge; → symmetry.

Defects or impurities in a CCD structure which prevent charges in certain pixels from being transferred to the next pixel.

Etymology (EN): → charge; trap, from O.E. træppe “snare, trap,” from P.Gmc. *trap-.

Etymology (PE): Talé “trap,” Mid.Pers. talag “trap, snare.”

Defects or impurities in a CCD structure which prevent charges in certain pixels from being transferred to the next pixel.

Etymology (EN): → charge; trap, from O.E. træppe “snare, trap,” from P.Gmc. *trap-.

Etymology (PE): Talé “trap,” Mid.Pers. talag “trap, snare.”

A solid-state detector that stores the electrons, produced by incident photons, in potential wells at the surface of a semiconductor. The packages of charge are moved about the surface by being transferred to similar adjacent potential wells. The wells are controlled by the manipulation of voltage applied to surface electrodes.

Etymology (EN): → charge; coupled adj. from → couple; → device.

A solid-state detector that stores the electrons, produced by incident photons, in potential wells at the surface of a semiconductor. The packages of charge are moved about the surface by being transferred to similar adjacent potential wells. The wells are controlled by the manipulation of voltage applied to surface electrodes.

Etymology (EN): → charge; coupled adj. from → couple; → device.

A charge-transfer device that passes along stored charges positioned at predetermined locations; it is used as an image sensor in which the image points are accessed by reference to their horizontal and vertical coordinates.

See also: → charge; → injection;
→ device.

A charge-transfer device that passes along stored charges positioned at predetermined locations; it is used as an image sensor in which the image points are accessed by reference to their horizontal and vertical coordinates.

See also: → charge; → injection;
→ device.

The laws of physics should be the same if a particle is interchanged with its → antiparticle (→ charge conjugation), or swapped for its mirror image (→ parity symmetry). It is known that charge-parity (CP) symmetry holds for interactions involving → electromagnetism, → gravitation, and → strong interactions, but CP violation is known to occur during → weak interactions involved in → radio decay. Same as → CP-symmetry.

See also: → charge; → parity;
→ symmetry.

The laws of physics should be the same if a particle is interchanged with its → antiparticle (→ charge conjugation), or swapped for its mirror image (→ parity symmetry). It is known that charge-parity (CP) symmetry holds for interactions involving → electromagnetism, → gravitation, and → strong interactions, but CP violation is known to occur during → weak interactions involved in → radio decay. Same as → CP-symmetry.

See also: → charge; → parity;
→ symmetry.

A semi-conductor device that relays stored charges positioned at predetermined locations, such as charge-coupled or charge-injection devices.

See also: → charge; → transfer;
→ device.

A semi-conductor device that relays stored charges positioned at predetermined locations, such as charge-coupled or charge-injection devices.

See also: → charge; → transfer;
→ device.

Fraction of the original charge which is successfully transferred from one pixel to the next in one CCD cycle.

See also: → charge; → transfer;
→ efficiency.

Fraction of the original charge which is successfully transferred from one pixel to the next in one CCD cycle.

See also: → charge; → transfer;
→ efficiency.

Quality of a → particle, → body, or → system that possesses → electric charge

Etymology (EN): Past participle of “to → charge.”

Etymology (PE): Bârdâr “charged,” from bâr, → cahrge, + dâr “having, possessor,” from dâštan “to have, to possess,” Mid.Pers. dâštan, O.Pers./Av. root dar- “to hold, keep back, maitain, keep in mind,” Skt. dhr-, dharma- “law,”
Gk. thronos “elevated seat, throne,” L. firmus “firm, stable,” Lith. daryti “to make,” PIE *dher- “to hold, support.”

Quality of a → particle, → body, or → system that possesses → electric charge

Etymology (EN): Past participle of “to → charge.”

Etymology (PE): Bârdâr “charged,” from bâr, → cahrge, + dâr “having, possessor,” from dâštan “to have, to possess,” Mid.Pers. dâštan, O.Pers./Av. root dar- “to hold, keep back, maitain, keep in mind,” Skt. dhr-, dharma- “law,”
Gk. thronos “elevated seat, throne,” L. firmus “firm, stable,” Lith. daryti “to make,” PIE *dher- “to hold, support.”

Any particle containing either a → positive or → negative → electric charge.

See also: → charged; → particle.

Any particle containing either a → positive or → negative → electric charge.

See also: → charged; → particle.

An → asteroid that belongs to the class of → Centaurs (discovered through stellar → occultation observations). At just 250 km across, Chariklo is the smallest body so far found to have rings. There are two dense rings, with respective widths of about 7 and 3 km, → optical depth of 0.4 and 0.06, and orbital radii of 391 and 405 km (see F. Braga-Ribas et al. Nature, 2014, 26 March).

See also: From Khariklo, the name of a nymph in Greek mythology, the wife of → Chiron and the daughter of → Apollo.

An → asteroid that belongs to the class of → Centaurs (discovered through stellar → occultation observations). At just 250 km across, Chariklo is the smallest body so far found to have rings. There are two dense rings, with respective widths of about 7 and 3 km, → optical depth of 0.4 and 0.06, and orbital radii of 391 and 405 km (see F. Braga-Ribas et al. Nature, 2014, 26 March).

See also: From Khariklo, the name of a nymph in Greek mythology, the wife of → Chiron and the daughter of → Apollo.

The volume of a fixed mass of any gas increases for each degree rise in temperature by a constant fraction of the volume at 0° C, the pressure being constant throughout.

Etymology (EN): Named after Jacques Charles (1746-1823), French physicist, who first discovered the law, and who was responsible for the first balloon ascents using hydrogen.

The volume of a fixed mass of any gas increases for each degree rise in temperature by a constant fraction of the volume at 0° C, the pressure being constant throughout.

Etymology (EN): Named after Jacques Charles (1746-1823), French physicist, who first discovered the law, and who was responsible for the first balloon ascents using hydrogen.

The largest satellite of Pluto. It is about 1,040 km across, roughly half Pluto’s diameter. Charon is unusual in that it is the largest moon with respect to its primary planet in the Solar System. Moreover, the Pluto-Charon system is extraordinary because the center of mass lies in open space between the two, a characteristic of a double planet system. Pluto and Charon are also tidally locked in a synchronous orbit. Pluto’s rotational period is 6.39 Earth days. It takes 6.39 days for Charon to make one revolution around Pluto. Thus, the two bodies continuously face each other. Also called Pluto I.

Etymology (EN): In Gk. mythology, Xαρον (Charon) was a figure who ferried the dead across the river Styx into Hades (the underworld).

The largest satellite of Pluto. It is about 1,040 km across, roughly half Pluto’s diameter. Charon is unusual in that it is the largest moon with respect to its primary planet in the Solar System. Moreover, the Pluto-Charon system is extraordinary because the center of mass lies in open space between the two, a characteristic of a double planet system. Pluto and Charon are also tidally locked in a synchronous orbit. Pluto’s rotational period is 6.39 Earth days. It takes 6.39 days for Charon to make one revolution around Pluto. Thus, the two bodies continuously face each other. Also called Pluto I.

Etymology (EN): In Gk. mythology, Xαρον (Charon) was a figure who ferried the dead across the river Styx into Hades (the underworld).

An elementary particle detector using a special apparatus capable of operating at high rates. The detector consists of an → array of many closely spaced parallel wires, or → anodes,
in an enclosure filled with a carefully chosen gas. The wires, being placed between two → cathode plates, are under high voltage. Each wire acts as an independent
→ proportional counter.
The particle that passes through the chamber will ionize surrounding gaseous atoms. The resulting ions and electrons are accelerated by the electric field around the wire, causing a localized cascade of ionization which brings about
an electric current proportional to the energy of the detected particle. Previous detectors, such as the → bubble chamber, could
record the tracks left by particles on photographic emulsions at the rate of only one or two per second. In comparison, the multiwire chamber records up to one million tracks per second in three dimensions with an accuracy of a tenth of a millimeter and moreover sends the data directly to a computer for analysis. The speed and precision of the multiwire chamber has revolutionized high-energy physics. For instance it was crucial in finding the predicted → W boson and → Z boson of the → electroweak interaction theory. Charpak’s chamber also has applications in medicine, biology, and industry. Also called → multiwire proportional chamber.

See also: In honor of Georges Charpak (1924-2010), a French physicist, who built the first detector of this type in 1968. He received
the Nobel Prize for physics in 1992; → detector.

An elementary particle detector using a special apparatus capable of operating at high rates. The detector consists of an → array of many closely spaced parallel wires, or → anodes,
in an enclosure filled with a carefully chosen gas. The wires, being placed between two → cathode plates, are under high voltage. Each wire acts as an independent
→ proportional counter.
The particle that passes through the chamber will ionize surrounding gaseous atoms. The resulting ions and electrons are accelerated by the electric field around the wire, causing a localized cascade of ionization which brings about
an electric current proportional to the energy of the detected particle. Previous detectors, such as the → bubble chamber, could
record the tracks left by particles on photographic emulsions at the rate of only one or two per second. In comparison, the multiwire chamber records up to one million tracks per second in three dimensions with an accuracy of a tenth of a millimeter and moreover sends the data directly to a computer for analysis. The speed and precision of the multiwire chamber has revolutionized high-energy physics. For instance it was crucial in finding the predicted → W boson and → Z boson of the → electroweak interaction theory. Charpak’s chamber also has applications in medicine, biology, and industry. Also called → multiwire proportional chamber.

See also: In honor of Georges Charpak (1924-2010), a French physicist, who built the first detector of this type in 1968. He received
the Nobel Prize for physics in 1992; → detector.

In astrogeology, long, narrow, steep sided depressions on planets and Moon, for example, Melas Chasma and Candor Chasma on Mars.

Etymology (EN): L. chasma, from Gk. khasma “yawning hollow, gulf,” related to khaskein “to yawn,” and thus to → chaos (1).

Etymology (PE): Karz “big fissure in a mountain,” from Qâeni dialect.

In astrogeology, long, narrow, steep sided depressions on planets and Moon, for example, Melas Chasma and Candor Chasma on Mars.

Etymology (EN): L. chasma, from Gk. khasma “yawning hollow, gulf,” related to khaskein “to yawn,” and thus to → chaos (1).

Etymology (PE): Karz “big fissure in a mountain,” from Qâeni dialect.

A → meteor exploded on February 15, 2013 over Chelyabinsk, southern Russia.The explosion occurred at a height of 20 km above Earth, releasing 500 kilotons → TNT equivalent of energy, approximately 30 times the yield of the nuclear bomb over Hiroshima. It caused a → shock wave that damaged 7,200 buildings in six Russian cities and injured some 1,500 people, mainly from flying glass. Later, about five tons of meteoritic material reached the ground, including a 650 kg → meteorite that was recovered by divers from the bottom of Lake Chebarkul, on the slopes of the southern Ural mountains. With an estimated initial mass of about 12,000-13,000 metric tons, and measuring about 20 m in diameter, it is the largest known natural object to have entered Earth’s atmosphere since the 1908 → Tunguska event.

See also: Chelyabinsk, a city in Russia, the capital of the Chelyabinsk region, on the eastern slope of the Ural Mountains on the Miass River, 200 km south of Ekaterinburg and 1,879 km east of Moscow. The population of Chelyabinsk is about 1,183,000 (2015), the area, 530 sq. km; → meteor.

A → meteor exploded on February 15, 2013 over Chelyabinsk, southern Russia.The explosion occurred at a height of 20 km above Earth, releasing 500 kilotons → TNT equivalent of energy, approximately 30 times the yield of the nuclear bomb over Hiroshima. It caused a → shock wave that damaged 7,200 buildings in six Russian cities and injured some 1,500 people, mainly from flying glass. Later, about five tons of meteoritic material reached the ground, including a 650 kg → meteorite that was recovered by divers from the bottom of Lake Chebarkul, on the slopes of the southern Ural mountains. With an estimated initial mass of about 12,000-13,000 metric tons, and measuring about 20 m in diameter, it is the largest known natural object to have entered Earth’s atmosphere since the 1908 → Tunguska event.

See also: Chelyabinsk, a city in Russia, the capital of the Chelyabinsk region, on the eastern slope of the Ural Mountains on the Miass River, 200 km south of Ekaterinburg and 1,879 km east of Moscow. The population of Chelyabinsk is about 1,183,000 (2015), the area, 530 sq. km; → meteor.

A combining form meaning “chemical, chemically induced, chemistry,” used in the formation of compound terms like → chemosynthesis. Also chem- (before a vowel) and chemo-.

See also: Chemi- extracted from → chemical or → chemistry.

A combining form meaning “chemical, chemically induced, chemistry,” used in the formation of compound terms like → chemosynthesis. Also chem- (before a vowel) and chemo-.

See also: Chemi- extracted from → chemical or → chemistry.

Of, relating to, used in, or produced by means of chemistry.

Etymology (EN): From chemic “of alchemy,” → chemistry + → -al.

Etymology (PE): Šimiyâyi, of or pertaining to šimi→ chemistry.
Šimik, from šim- + -ik, → -ic.

Of, relating to, used in, or produced by means of chemistry.

Etymology (EN): From chemic “of alchemy,” → chemistry + → -al.

Etymology (PE): Šimiyâyi, of or pertaining to šimi→ chemistry.
Šimik, from šim- + -ik, → -ic.

The relative amount of a given → chemical element or → chemical compound
with respect to another element or compound in a given sample.

See also: → chemical; → abundance.

The relative amount of a given → chemical element or → chemical compound
with respect to another element or compound in a given sample.

See also: → chemical; → abundance.

Same as → chemisorption.

See also: → chemical; → adsorption.

Same as → chemisorption.

See also: → chemical; → adsorption.

The extent to which a chemical species, such as an atom or molecule, tends to combine with another to form a chemical compound.

See also: → chemical; → affinity.

The extent to which a chemical species, such as an atom or molecule, tends to combine with another to form a chemical compound.

See also: → chemical; → affinity.

A force by which chemical substances are held together by attraction of atoms to each other through sharing, as well as exchanging, of electrons.

See also: → chemical; → bond.

A force by which chemical substances are held together by attraction of atoms to each other through sharing, as well as exchanging, of electrons.

See also: → chemical; → bond.

The identities, and relative abundances of the → chemical elements or → compounds that make up a substance.

See also: → chemical; → composition.

The identities, and relative abundances of the → chemical elements or → compounds that make up a substance.

See also: → chemical; → composition.

A substance whose molecules are made up of atoms of at least two
different elements.

See also: → chemical; → compound.

A substance whose molecules are made up of atoms of at least two
different elements.

See also: → chemical; → compound.

A substance which consists entirely of atoms of the same → atomic number and cannot be decomposed or changed into another substance using chemical means. Currently 118 chemical elements are known, the most abundant being → hydrogen. → periodic table.

See also: → chemical; → element.

A substance which consists entirely of atoms of the same → atomic number and cannot be decomposed or changed into another substance using chemical means. Currently 118 chemical elements are known, the most abundant being → hydrogen. → periodic table.

See also: → chemical; → element.

The → process by which the relative → abundance of a given → chemical element or → species in an → astrophysical object is increased. For example the the → increase of the → heavy element content of the → interstellar medium due to → stellar evolution.

See also: → chemical; → enrichment.

The → process by which the relative → abundance of a given → chemical element or → species in an → astrophysical object is increased. For example the the → increase of the → heavy element content of the → interstellar medium due to → stellar evolution.

See also: → chemical; → enrichment.

The symbolic representation of a chemical reaction where the formulae of the → reactants are placed on the left and the formulae of → products on the right of an arrow.

See also: → chemical; → equation.

The symbolic representation of a chemical reaction where the formulae of the → reactants are placed on the left and the formulae of → products on the right of an arrow.

See also: → chemical; → equation.

A cumulative change in the chemical properties, or more specifically, the relative abundances of chemical elements in an astrophysical system.

See also: → chemical; → evolution.

A cumulative change in the chemical properties, or more specifically, the relative abundances of chemical elements in an astrophysical system.

See also: → chemical; → evolution.

→ mixing process.

See also: → chemical; → mixing.

→ mixing process.

See also: → chemical; → mixing.

For a given component in a → gas mixture, the change in → Gibbs free energy (G) with respect to change in amount of the component (n), when pressure, temperature, and amounts of other components remain constant: ∂G/∂n. Components are in equilibrium if their chemical potentials are equal.

See also: → chemical; → potential.

For a given component in a → gas mixture, the change in → Gibbs free energy (G) with respect to change in amount of the component (n), when pressure, temperature, and amounts of other components remain constant: ∂G/∂n. Components are in equilibrium if their chemical potentials are equal.

See also: → chemical; → potential.

A → change or → transformation in which a → substance → decomposes, → combines with other → substances, or interchanges constituents with other substances.

See also: → chemical; → reaction.

A → change or → transformation in which a → substance → decomposes, → combines with other → substances, or interchanges constituents with other substances.

See also: → chemical; → reaction.

The physical processes that can cause certain elements to migrate in a → stellar atmosphere. These processes are thought to be important in creating the chemical peculiarities seen in
→ Am stars and → Ap stars.

See also: → chemical; → separation.

The physical processes that can cause certain elements to migrate in a → stellar atmosphere. These processes are thought to be important in creating the chemical peculiarities seen in
→ Am stars and → Ap stars.

See also: → chemical; → separation.

A set of chemically → identical  → atomic or → molecular entities.

See also: → chemical; → species.

A set of chemically → identical  → atomic or → molecular entities.

See also: → chemical; → species.

A → main sequence star of → spectral type A or B (→ A-type star, → B-type star) identified by the presence of anomalously strong or weak → absorption lines of certain elements in their spectra.
CP stars have been divided into four main classes on the basis of their spectra: 1) non-magnetic metallic-lined (CP1, → Am star), magnetic (CP2, → Ap star), non-magnetic mercury-manganese (CP3, → HgMn star), and helium-weak (CP4, → He-weak star).

See also → Ap/Bp stars.

See also: → chemical; → -ly; → peculiar; → star.

A → main sequence star of → spectral type A or B (→ A-type star, → B-type star) identified by the presence of anomalously strong or weak → absorption lines of certain elements in their spectra.
CP stars have been divided into four main classes on the basis of their spectra: 1) non-magnetic metallic-lined (CP1, → Am star), magnetic (CP2, → Ap star), non-magnetic mercury-manganese (CP3, → HgMn star), and helium-weak (CP4, → He-weak star).

See also → Ap/Bp stars.

See also: → chemical; → -ly; → peculiar; → star.

The production and emission of light via a → chemical reaction.

See also: Chemi-, → chemo-; → luminescence.

The production and emission of light via a → chemical reaction.

See also: Chemi-, → chemo-; → luminescence.

A kind of → adsorption in which the forces involved are → valence forces of the same kind as those operating in the formation of → chemical compounds. Same as → chemical adsorption. See also → physisorption.

See also: Chemi-, from → chemical; → sorption.

A kind of → adsorption in which the forces involved are → valence forces of the same kind as those operating in the formation of → chemical compounds. Same as → chemical adsorption. See also → physisorption.

See also: Chemi-, from → chemical; → sorption.

The science of the composition, structure, properties, and reactions of chemical elements and compounds and their interactions with matter and energy.

Etymology (EN): Chemistry, from chemist, from Gk. chemia “alchemy” + -ry, from M.E. -rie, from O.Fr.

Etymology (PE): Šimi, from Fr. as above.

The science of the composition, structure, properties, and reactions of chemical elements and compounds and their interactions with matter and energy.

Etymology (EN): Chemistry, from chemist, from Gk. chemia “alchemy” + -ry, from M.E. -rie, from O.Fr.

Etymology (PE): Šimi, from Fr. as above.

A combining form meaning “chemical, chemically induced, chemistry,” used in the formation of compound terms like → chemosynthesis. Also chem- (before a vowel) and chemi- (before elements of L. origin).

See also: Chemo- extracted from → chemical or → chemistry.

A combining form meaning “chemical, chemically induced, chemistry,” used in the formation of compound terms like → chemosynthesis. Also chem- (before a vowel) and chemi- (before elements of L. origin).

See also: Chemo- extracted from → chemical or → chemistry.

In biochemistry, the ability to produce organic compounds using energy contained in inorganic molecules. Chemosynthesis is similar to → photosynthesis. Instead of using light as an energy source to make food, energy or compounds from chemical reactions is used. Most chemosynthetic organisms are bacteria.

See also: → chemo-; → synthesis.

In biochemistry, the ability to produce organic compounds using energy contained in inorganic molecules. Chemosynthesis is similar to → photosynthesis. Instead of using light as an energy source to make food, energy or compounds from chemical reactions is used. Most chemosynthetic organisms are bacteria.

See also: → chemo-; → synthesis.

The first mission, conducted by the → European Space Agency, dedicated to searching for → exoplanetary transits by performing ultra-high precision → photometry on bright stars already known to host planets. Launched on 18 December 2019, Cheops is a small spacecraft with a launch mass (including propellant) of approximately 280 kg. It has a single instrument: a high precision → photometer with a 300 mm effective aperture telescope and a single → charge-coupled device (CCD) → detector covering → visible to → near-infrared wavelengths.

The mission’s main science goals are to measure the bulk density of → super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterization studies of → exoplanets in these mass and size ranges.

See also: CHEOPS, short for CHaracterising ExOPlanet Satellite.

The first mission, conducted by the → European Space Agency, dedicated to searching for → exoplanetary transits by performing ultra-high precision → photometry on bright stars already known to host planets. Launched on 18 December 2019, Cheops is a small spacecraft with a launch mass (including propellant) of approximately 280 kg. It has a single instrument: a high precision → photometer with a 300 mm effective aperture telescope and a single → charge-coupled device (CCD) → detector covering → visible to → near-infrared wavelengths.

The mission’s main science goals are to measure the bulk density of → super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterization studies of → exoplanets in these mass and size ranges.

See also: CHEOPS, short for CHaracterising ExOPlanet Satellite.

Visible radiation emitted when → charged particles pass through a transparent medium faster than the speed of light in that medium.

Etymology (EN): Named after Pavel A. Čerenkov (1904-1990), Russian physicist, who discovered the phenomenon. He shared the Nobel prize 1958 in physics
with Ilya Frank and Igor Tamm, who in 1937 gave the theoretical explanation for this radiation.

Visible radiation emitted when → charged particles pass through a transparent medium faster than the speed of light in that medium.

Etymology (EN): Named after Pavel A. Čerenkov (1904-1990), Russian physicist, who discovered the phenomenon. He shared the Nobel prize 1958 in physics
with Ilya Frank and Igor Tamm, who in 1937 gave the theoretical explanation for this radiation.

A probability density function, denoted χ², that gives the distribution of the sum of squares of k independent random variables, each being drawn from the normal distribution with zero mean and unit variance. The integer k is the number of degrees of freedom. The distribution has a positive skew; the skew is less with more degrees of freedom. As degrees of freedom increase, the chi-square distribution approaches a normal distribution. The most common application is chi-square tests for goodness of fit of an observed distribution to a theoretical one. If χ² = 0 the agreement is perfect.

Etymology (EN): Chi Gk. letter of alphabet; → square; → distribution.

Etymology (PE): Vâbâžeš, → distribution; do, → two.

A probability density function, denoted χ², that gives the distribution of the sum of squares of k independent random variables, each being drawn from the normal distribution with zero mean and unit variance. The integer k is the number of degrees of freedom. The distribution has a positive skew; the skew is less with more degrees of freedom. As degrees of freedom increase, the chi-square distribution approaches a normal distribution. The most common application is chi-square tests for goodness of fit of an observed distribution to a theoretical one. If χ² = 0 the agreement is perfect.

Etymology (EN): Chi Gk. letter of alphabet; → square; → distribution.

Etymology (PE): Vâbâžeš, → distribution; do, → two.

A crater about 200 km in diameter on the northern coast of the Yucatan Peninsula, near the town of Chicxulub, Mexico. It is attributed to a 10 km wide → asteroid that hit the Earth about 65 million years ago (→ Chicxulub impactor).

Ten years before the 1990 discovery of the Chicxulub crater, physicist Luis Alvarez and geologist Walter Alvarez proposed a theory to explain the formation of the crater. They noted increased concentrations of the element → iridium in 65-million-year-old clay. Iridium is rare on Earth, but it’s more common in some objects from space, like → meteors and asteroids. According to the Alvarez theory, a massive asteroid had hit the Earth, blanketing the world in iridium. The collision caused fires, climate change and widespread extinctions, among which that of dinosaurs, who had lived for 180 million years.

See also: Named after a twon in the Mexican state of Yucatan, which lies near the geographic center of the → crater.

A crater about 200 km in diameter on the northern coast of the Yucatan Peninsula, near the town of Chicxulub, Mexico. It is attributed to a 10 km wide → asteroid that hit the Earth about 65 million years ago (→ Chicxulub impactor).

Ten years before the 1990 discovery of the Chicxulub crater, physicist Luis Alvarez and geologist Walter Alvarez proposed a theory to explain the formation of the crater. They noted increased concentrations of the element → iridium in 65-million-year-old clay. Iridium is rare on Earth, but it’s more common in some objects from space, like → meteors and asteroids. According to the Alvarez theory, a massive asteroid had hit the Earth, blanketing the world in iridium. The collision caused fires, climate change and widespread extinctions, among which that of dinosaurs, who had lived for 180 million years.

See also: Named after a twon in the Mexican state of Yucatan, which lies near the geographic center of the → crater.

An object having an estimated mass between 1.0 × 10¹⁵ and 4.6 × 10¹⁷ kg, which struck the Earth at the → Cretaceous-Tertiary event about 65 million years ago. It was probably an → asteroid 10 km in diameter with a velocity of roughly 20 km per sec at an angle of just under 60°. The collision
created the → Chicxulub crater. The event was responsible for eliminating approximately 70 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods.

See also: → Chicxulub crater; → impactor.

An object having an estimated mass between 1.0 × 10¹⁵ and 4.6 × 10¹⁷ kg, which struck the Earth at the → Cretaceous-Tertiary event about 65 million years ago. It was probably an → asteroid 10 km in diameter with a velocity of roughly 20 km per sec at an angle of just under 60°. The collision
created the → Chicxulub crater. The event was responsible for eliminating approximately 70 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods.

See also: → Chicxulub crater; → impactor.

1. A person between birth and puberty; a son or daughter; an offspring.
   

   2. In → graph theory, the → vertex (node) below a given vertex connected by its → edge downward. In other words, in a rooted tree, a vertex v is a child of vertex w if v immediately succeeds w on the path from the root to v. Vertex v is a child of w if and only if w is the parent of v.

Etymology (EN): M.E.; O.E. cild “fetus, infant;” akin to Goth. kilthai “womb.”

Etymology (PE): Farzand, from Mid.Pers. frazand “child;” Av. frazanti- “progeny, offspring,” from fra- “forward, along,” → pro-, + zan “to give birth;” → birth.

1. A person between birth and puberty; a son or daughter; an offspring.
   

   2. In → graph theory, the → vertex (node) below a given vertex connected by its → edge downward. In other words, in a rooted tree, a vertex v is a child of vertex w if v immediately succeeds w on the path from the root to v. Vertex v is a child of w if and only if w is the parent of v.

Etymology (EN): M.E.; O.E. cild “fetus, infant;” akin to Goth. kilthai “womb.”

Etymology (PE): Farzand, from Mid.Pers. frazand “child;” Av. frazanti- “progeny, offspring,” from fra- “forward, along,” → pro-, + zan “to give birth;” → birth.

A → lunisolar calendar (Chinese: yīnyáng li),
which is now mainly used for determining cultural festivals. It is based on astronomical observations of the Sun’s annual apparent motion (→ ecliptic) and → lunar phases. The calendar starts at Chinese New Year and consists of 12 or 13 → lunar months. The ecliptic is divided into 24 sections (jiéqi) of 15° each. In general, Chinese New Year falls on the day of the second new Moon after the → winter solstice on approximately December 22. Since 12 months are about 11 days shorter than the → tropical year, a → leap month is inserted to keep the calendar in tune with the seasons.
An ordinary → lunar year
has 353-355 days while a → leap year has 383-385 days. Therefore, the → solstices and → equinoxes move 11 (or 10 or 12) days later. Each 13-month leap year is about 19 days too long, so the solstices and equinoxes jump 19 (or 18 or 20) days earlier. Each year is assigned a name consisting of two components within a 60-year cycle. The first component is a celestial stem. The second component is a terrestrial branch; it features the names of animals in a zodiac cycle consisting of 12 animals. Each of the two components is used sequentially. Therefore, the first year of the 60-year cycle becomes jia-zi, the second year is yi-chou, and so on. One starts from the beginning when the end of a component is reached. The 60th year is gui-hai. The current 60-year cycle started on 2 February 1984. The leap year must be inserted if there are 13 new moons from the start of the 11th month in the first year to the start of the 11th month in the second year. The beginnings of the Chinese calendar can be traced back to the 14th century BC. Legend has it that the Emperor Huang-di invented the calendar in 2637 BC. The calendar has been adopted by several southeast Asian cultures.
The Chinese calendar has undergone several reforms, the last one in 1645. For more details, see, e.g., Helmer Aslaksen, The Mathematics of the Chinese calendar, e-paper.

See also: Chinese adj. of China, from Pers. Cin [Chin], from Qin the first imperial dynasty of China (221 to 206 BC); → calendar.

A → lunisolar calendar (Chinese: yīnyáng li),
which is now mainly used for determining cultural festivals. It is based on astronomical observations of the Sun’s annual apparent motion (→ ecliptic) and → lunar phases. The calendar starts at Chinese New Year and consists of 12 or 13 → lunar months. The ecliptic is divided into 24 sections (jiéqi) of 15° each. In general, Chinese New Year falls on the day of the second new Moon after the → winter solstice on approximately December 22. Since 12 months are about 11 days shorter than the → tropical year, a → leap month is inserted to keep the calendar in tune with the seasons.
An ordinary → lunar year
has 353-355 days while a → leap year has 383-385 days. Therefore, the → solstices and → equinoxes move 11 (or 10 or 12) days later. Each 13-month leap year is about 19 days too long, so the solstices and equinoxes jump 19 (or 18 or 20) days earlier. Each year is assigned a name consisting of two components within a 60-year cycle. The first component is a celestial stem. The second component is a terrestrial branch; it features the names of animals in a zodiac cycle consisting of 12 animals. Each of the two components is used sequentially. Therefore, the first year of the 60-year cycle becomes jia-zi, the second year is yi-chou, and so on. One starts from the beginning when the end of a component is reached. The 60th year is gui-hai. The current 60-year cycle started on 2 February 1984. The leap year must be inserted if there are 13 new moons from the start of the 11th month in the first year to the start of the 11th month in the second year. The beginnings of the Chinese calendar can be traced back to the 14th century BC. Legend has it that the Emperor Huang-di invented the calendar in 2637 BC. The calendar has been adopted by several southeast Asian cultures.
The Chinese calendar has undergone several reforms, the last one in 1645. For more details, see, e.g., Helmer Aslaksen, The Mathematics of the Chinese calendar, e-paper.

See also: Chinese adj. of China, from Pers. Cin [Chin], from Qin the first imperial dynasty of China (221 to 206 BC); → calendar.

The quality of an object that is not superimposable on its mirror image.

Etymology (EN): From Gk. cheir “hand;” from PIE *ghes- “hand.”

Etymology (PE): Xirâl, loan from Gk., as above.

The quality of an object that is not superimposable on its mirror image.

Etymology (EN): From Gk. cheir “hand;” from PIE *ghes- “hand.”

Etymology (PE): Xirâl, loan from Gk., as above.

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

See also: → chiral; → -ity.

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

See also: → chiral; → -ity.

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.

Etymology (EN): 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.

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.

Etymology (EN): 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.

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.

Etymology (EN): Chirp “a short, high-pitched sound, such as that made by certain birds or insects,” from M.E. chirpen, of onomatopoeic origin.

Etymology (PE): Cirp loanword from E., as above.

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.

Etymology (EN): Chirp “a short, high-pitched sound, such as that made by certain birds or insects,” from M.E. chirpen, of onomatopoeic origin.

Etymology (PE): Cirp loanword from E., as above.

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

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

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

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

1. A negative ion, ClO₃^- derived from chloric acid.
   

2. Any salt of chloric acid.

See also: From chlor-, → chlorine, + → -ate.

1. A negative ion, ClO₃^- derived from chloric acid.
   

2. Any salt of chloric acid.

See also: From chlor-, → chlorine, + → -ate.

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

See also: From chlor-, → chlorine, + → -ic; → acid.

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

See also: From chlor-, → chlorine, + → -ic; → acid.

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.

See also: From Gk. chloros “light green, greenish yellow;” cognate with Pers. zard “yellow,” zarr “gold;” E. → gold, → yellow.

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.

See also: From Gk. chloros “light green, greenish yellow;” cognate with Pers. zard “yellow,” zarr “gold;” E. → gold, → yellow.

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.

See also: Chondrite, from chondr-, from chondros “grain”,

• suffix → -ite.

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.

See also: Chondrite, from chondr-, from chondros “grain”,

• suffix → -ite.

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.

See also: From Gk. chondr-, from chondros “grain,” + diminutive suffix → -ule.

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.

See also: From Gk. chondr-, from chondros “grain,” + diminutive suffix → -ule.

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

Etymology (EN): M.E. choghe; akin to O.E. ceo, Du. kauw, Dan. kaa.

Etymology (PE): Kalajik, from Daštak Baxtiyâri dialect, related to kal, kalâq, → crow.

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

Etymology (EN): M.E. choghe; akin to O.E. ceo, Du. kauw, Dan. kaa.

Etymology (PE): Kalajik, from Daštak Baxtiyâri dialect, related to kal, kalâq, → crow.

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.

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

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.

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

Of or relating to color or color phenomena or sensations.

Etymology (EN): From L. chromaticus, from Gk. khromatikos “relating to color,” from khroma, khromat- “color” + → -ic.

Etymology (PE): From rang, fâm, → chromo-, + -i adj. suffix.

Of or relating to color or color phenomena or sensations.

Etymology (EN): From L. chromaticus, from Gk. khromatikos “relating to color,” from khroma, khromat- “color” + → -ic.

Etymology (PE): From rang, fâm, → chromo-, + -i adj. suffix.

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.

See also: → chromatic; → aberration.

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.

See also: → chromatic; → aberration.

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).

See also: From the Gk. chroma “color,” from the many colored compounds of this element,

• -ium a suffix used in the name of several chemical elements.

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).

See also: From the Gk. chroma “color,” from the many colored compounds of this element,

• -ium a suffix used in the name of several chemical elements.

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

Etymology (EN): Combining form from Gk. chroma, khroma “color.”

Etymology (PE): 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.”

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

Etymology (EN): Combining form from Gk. chroma, khroma “color.”

Etymology (PE): 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.”

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.

See also: → chromo-; → dynamics.

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.

See also: → chromo-; → dynamics.

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).

See also: → 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.

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).

See also: → 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.

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

Etymology (EN): Chronograph, from Gk. khronos “time” + → -graph.

Etymology (PE): Gâhnegâr, from gâh “time” + negâr, → -graph.

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

Etymology (EN): Chronograph, from Gk. khronos “time” + → -graph.

Etymology (PE): Gâhnegâr, from gâh “time” + negâr, → -graph.

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

Etymology (EN): Chronology, from Gk. khronos “time” + → -logy.

Etymology (PE): 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.

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

Etymology (EN): Chronology, from Gk. khronos “time” + → -logy.

Etymology (PE): 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.

A highly precise timepiece.

Etymology (EN): Chronometer, from from Gk. khronos “time” + → -meter.

Etymology (PE): Gâhsanj, zamânsanj, from gâh or zamân “time” + -sanj→ -meter.

A highly precise timepiece.

Etymology (EN): Chronometer, from from Gk. khronos “time” + → -meter.

Etymology (PE): Gâhsanj, zamânsanj, from gâh or zamân “time” + -sanj→ -meter.

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 (Dictionary.com).

Etymology (EN): 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.

Etymology (PE): Gavis “churn,” of unknown origin.

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 (Dictionary.com).

Etymology (EN): 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.

Etymology (PE): Gavis “churn,” of unknown origin.

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).

See also: Verbal noun of → churn.

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).

See also: Verbal noun of → churn.