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

A combining form meaning "house, household, environment, nature, natural habitat."

Ultimately from Gk. oikos "house," cognate with L. villa "country house, farm," related to vicus "village, group of houses; " cf. Av. vis- "homestead, community;" O.Pers. viθ- "house, royal house, farm;" Mid.Pers. wis "village;" dialectal Pers. wiš-, vīš- "to set (of Sun)," wīs- "to enter" (Cheung 2007); Skt. viś- "settlement, house, tribe, people;" Goth. weihs "village;" Lith. viešpats "master of the house;" PIE *ueik'- "to settle (down)."

Bum-, from bum "region, land, a mansion or place where one dwells in saftey; nature, disposition;" Mid.Pers. bûm "land, earth, country;" O.Pers. būmi- "place of being/living, land, region;" Av. būmī- "earth," from bav- "to be, become, take place;" cf. Skt. bhūmi- "land, region;" PIE *bheu- "to be, come into being, become" (cf. Gk. phu- "become," phuein "to bring forth, make grow;" L. fui "I was" (perf. tense of esse), futurus "that is to be, future;" Ger. present first and second person sing. bin, bist; E. to be; O.Ir. bi'u "I am;" Lith. bu'ti "to be;" Rus. byt' "to be").

1) The scientific discipline that is concerned with the relationships between living organisms and their past, present, and future environments.
2) The study of the damaging effects of modern civilisation on the environment, with the aim of prevention or reversal through conservation.

→ eco- + → -logy.

1) Pertaining to the production, distribution, and use of income, wealth, and commodities.
2) Of or relating to the science of economics.
3) Pertaining to an economy, or system of organization or operation, especially of the process of production (Dictionary.com).

Adjective, from → economics.

An increase in the output that an economy produces over a period of time.

→ economic; → growth.

1) Avoiding waste or extravagance; thrifty.
2) → economic.

→ economic; → -al.

The science that deals with description and analysis of the production, distribution, and consumption of goods and services.

From L. oeconomicus "well ordered," from Gk. oikonomikos "practiced in the management of a household or family," from oikonomia, from oiko- "house," → eco-, + -nomia "rule, law," → -nomy; + → -ics.

Bum, → eco- + -dât, → -nomy, + -ik, → -ics.

1) To practice economy; avoid waste or extravagance.
2) To manage economically; use sparingly or frugally (Dictionary.com).

From econom(y), → economy, + → -ize.

1) Thrifty and efficient use of material resources of a community, society, or household; frugality in expenditures.
2) An act or means of thrifty saving; a saving.
3) The management of the resources of a community, country, etc., especially with a view to its productivity (Dictionary.com).

From M.Fr. economie, → economics.

Bumdât, back formation from bumdâti, → economic.

The fabrication of a stable, enduring → ecosystem on a lifeless planet. It is the last stage of a → terraforming process.

From → eco- "house, dwelling place," + poiesis a combining form meaning "making, formation; poetry," from Gk. poesy, from poiein "to make, compose." Coined by Robert Hall Haynes (1931-1998), a Canadian geneticist and biophysicist.

Bum-âfarini, literally "creating environment," from bum "region, land," → eco- + âfarini "creation," from âfaridan, âfarin- "to create," from Mid.Pers. âfridan, âfrin- "to praise, bless; create," ultimately from Proto-Iranian āfrīta-, from prefixed frī- "to praise; to like;" cf. Av. frāy- "to satisfy, propitiate, pray;" Skt. prī- "to gladden, show favor to," prīta- "glad;" Gk. praus "gentle."

The space around a star in which a planet would experience external conditions that are not incompatible with the existence of life.

Ecosphere, from eco-, → ecology, + → sphere.

Bumsepehr, from bum "eco-," → ecology, + sepehr, → sphere.

Any geographic area that includes all of the organisms and nonliving parts of their physical environment.

→ ecology; → system.

Same as → Eddington parameter.

→ Eddington limit; → factor.

The theoretical upper limit of → luminosity at which the → radiation pressure of a light-emitting body would exceed the body's → gravitational attraction. A star emitting radiation at greater than the Eddington limit would break up. The Eddington luminosity for a non-rotating star is expressed as: L_Edd = 4πGMm_pcσ_T^-1, where G is the → gravitational constant, M the star mass, m_p the → proton mass, c the → speed of light, and σ_T the → Thomson cross section. It can also be written as L_Edd = 4πGMcκ^-1, where κ is the → opacity. In terms of solar mass, the Eddington limit can be expressed by: L_Edd = 1.26 × 10³⁸ (M/Msun) erg s^-1. See also → rotational Eddington limit.

Named after Arthur Stanley Eddington (1882-1944), prominent British astrophysicist; → limit.

Same as → Eddington limit.

→ Eddington limit; → luminosity.

A → dimensionless parameter indicating the degree to which a star is close to the → Eddington limit. It is expressed as Γ = L / L_Edd = κ L / (4πGMc), where L and M are the star luminosity and mass respectively, κ is the opacity, c the speed of light, and G the → gravitational constant. At the Eddington limit, Γ = 1, the star would become unbound. Because stellar luminosity generally scales with a high power of the stellar mass (L∝ M^3-4), → massive stars with M larger than 10 Msun generally have electron Eddington parameters of order Γ ≅ 0.1-1.

After Arthur Stanley Eddington (1882-1944), prominent British astrophysicist; → parameter.

A theoretical model in which the → cosmological constant plays a crucial role by allowing an initial phase that is identical to the Einstein static Universe. After an arbitrarily long time, the Universe begins to expand. The difficulty with this model is that the initiation of galaxy formation may actually cause a collapse rather than initiate an → expansion of the Universe.

→ Eddington limit; Lemaître in honor of Georges-Henri Lemaître (1894-1966), a Belgian Roman Catholic priest, who first proposed the Big Bang theory; → universe.

The time required for the redistribution of → angular momentum due to → meridional circulation. The Eddington-Sweet time for a uniformly → rotating star is expressed as: τ_ES = τ_KH . GM / (Ω² R³), where τ_KH is the → Kelvin-Helmholtz time scale, R, M, and L designate the radius, mass, and luminosity respectively, Ω the → angular velocity, and G the → gravitational constant. The Eddington-Sweet time scale can be approximated by τ_ES≅ τ_KH / χ, where χ is the ratio of the → centrifugal force to → gravity. For the Sun, χ ≅ 10^-5 resulting in an Eddington-Sweet time scale which is too long (10¹² years), i.e. unimportant. In contrast, for a rotating → massive star  χ is not so much less than 1. Hence the Eddington-Sweet circulation is very important in massive stars.

Named after the prominent British astrophysicist Arthur S. Eddington (1882-1944), who was the first to suggest these currents (in The Internal Constitution of the Stars, Dover Pub. Inc., New York, 1926) and P. A. Sweet who later quantified them (1950, MNRAS 110, 548); → time scale.

A deviation in the steady flow of a fluid causing a vortex-like motion running contrary to the general flow.
Meteo.: A small disturbance of wind in a large wind flow, which can produce turbulent conditions or turbulence.

Late M.E., from O.E. ed- "turning" + ea "water;" akin to O.N. itha.

Gižâv, from dialectical Kurd. "whirlpool," from giž "turning," Pers. gij "giddy-headed, vertigio;" Laki géž "whirlpool," vagéža "whirlwind" + âv, variant âb "water" (Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook").

An induced current circulating in masses of metal moving in a magnetic field or located in a changing magnetic field. Also known as → Foucault current.

→ eddy; → current.

A macroscopic process that occurs in a → fluid because of the relative motions induced by the non-uniform → turbulent motions of the fluid. Also known as turbulent → diffusion. Eddy diffusion may occur in an atmosphere if it is unstable against turbulence. It dominates the atmosphere below the homopause. See also → molecular diffusion.

→ eddy; → diffusion.