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

An object whose angular size exceeds the resolution of the instrument used to observe it.

→ extended; → object.

In radio astronomy, a source whose angular extent could be measured, as distinguished from a point source.

→ extended; → source.

1) An act or instance of extending; the state of being extended.
2) Physics: That property of a body by which it occupies space.
3) Math.: A field F is said to be an extension of a field K if K is a subfield of F.
4) Logic: The sum of all individuals or objects to which the comprehension of a term is applied. For example, the extension of the term "dog" is the set of all (past, present and future) dogs in the world.

Verbal noun of → extend.

The range over which a thing extends; length, area, volume, or scope.

→ extension.

1) Outer; being on the outer side; situated or being outside, which is outside.
2) Outside; an exterior part or surface.

From L. exterior "outward, outer, exterior," comparative of exterus "on the outside, outward, outer, foreign," itself a comparative of → ex- "out of."

Boruni, from borun, variant of birun "out, the outside," → out.

1) Any of the four angles that do not include a region of the space between two lines intersected by a third straight line (→ transversal).
2) The angle between any side and an extension of an adjacent side of a polygon.

→ exterior; → angle.

Of or pertaining to the outside or outer part.

M.E., from M.Fr. externe or directly from L. externus "outside, outward," from exterus, a comparative of → ex-, + → -al.

Biruni, adj. from birun "out, the outside," → out.

The → photoelectric effect in solids where free electrons are emitted from the surface of a substance (e.g., → semiconductor) when radiation of appropriate frequency falls on it. Also called → photoemissive effect.

→ external; → photoelectric; → effect.

The work done by a thermodynamic system as it expands against its surrounding environment. It is equal to ∫pdV, where p is the applied external pressure and V the volume, integrated from the initial V₁ to final V₂.

→ external; → work.

Verbal noun of → externalize.

→ externalize + → -tion.

1) To make external; embody in an outward form.
2) To regard or treat as being caused by externals; attribute to external causes (Dictionary.com).

→ external + → -ize.

1) Dimming of light by an intervening medium (the Earth's atmosphere or the interstellar medium). It is usually due to both scattering and absorption.
2) Paleontology: The act or process of dying out or coming to an end, becoming extinct: the extinction of a species; → mass extinction.

Noun of extinct, from L. extinctus, p.p. of extinguere "to quench, wipe out," from → ex- "out" + stinguere "to quench," from PIE base *steig- "to prick, stick, pierce;" cf. Mod.Pers. tiz, tež, tig, tej, tij, tiq "sharp;" Av. tiγra- "pointed," tiγray- "arrow;" → deblur.

Xâmuši, noun of xâmuš "extinguished; silent," Mid.Pers. xâmôš "silent;" cf. Skt. amrs- "to bear patiently."

Gradient of apparent magnitude with air mass.

→ extinction; → coefficient.

In → photometric calibration, the correction for energy loss undergone by radiation due to the → atmospheric extinction. Extinction correction is done using → standard stars observed at different → airmasses.

→ extinction; → correction.

A graph representing the variation of the → interstellar extinction against → wavelength. Usually it displays the → normalized values of extinction as a function of (the → inverse) of the wavelength (in → microns). See, e.g., Sandage & Mathis, 1979, Ann. Rev. Astron. Astrophys. 17, 73.

→ extinction; → curve.

Stars specifically observed at selected air masses in view of determining the atmospheric extinction coefficients.

→ extinction; → star.

A facility at → European Southern Observatory (ESO)'s → La Silla Observatory funded by the European Research Council and the French Agence National de la Recherche with the purpose of detecting and studying → transiting  → exoplanets. ExTrA will search for Earth-sized planets orbiting nearby → red dwarf stars. It uses three 0.6-metre telescopes. They regularly monitor the amount of light received from many red dwarf stars and look for a slight dip in brightness that could be caused by a planet passing across a star's disk and obscuring some of its light. The three ExTra telescopes collect light from the target star and four comparison stars and that light is then fed through optical fibres into a → multi-object spectrograph. This innovative approach of adding → spectroscopic information to traditional photometry helps mitigate the disruptive effect of Earth's atmosphere, as well as effects introduced by instruments and detectors, thus increasing the precision achievable.

ExTrA, short for Exoplanets in Transits and their Atmospheres, → exoplanet; → transit; → atmosphere.

Prefix meaning "outside; beyond the scope of; in addition to what is used or expected." Also extro-.

M.E., from L. extra, adverb and preposition, "outside, except, beyond," from exter "outward, on the outside."

Ostar-, from os-, → ex-, + -tar comparative suffix (Mid.Pers. -tar; Av. -tara; PIE base *-tero); borun-, from borun "out, the outside" (Mid.Pers. bêron, from bê "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river").

1a) To draw or pull out, often with great force or effort.
1b) To obtain from a substance by chemical or mechanical action, as by pressure, distillation, or evaporation.
1c) To derive or obtain (information, for example) from a source.
1d) Math.: To determine or calculate (the root of a number).
2) Something extracted (FreeDictionary.com).

From L. extractus, p.p. of extrahere "to draw out," from → ex-"out, out of" + trahere "to draw" "to pull, draw," from PIE root *tragh- "to draw, drag, move."

Barhanjidan, from bar- "on; upon; against; before; at; in," → object, + hanjidan "to draw, to pull," variants âxtan, âhixtan, âhiz-, halanjidan, lenjidan; Mid.Pers. âhynj- "to draw up," other Pers. cognate sanjidan, farhang, nehang, etc.; ultimately from prefixed (*a-) Proto-Ir. *θanj- "to pull, draw;" Av. θanj- "to pull, to draw."

1) The act of extracting or the condition of being extracted.
2) Something obtained by extracting; an extract (FreeDictionary.com).

→ extract; → -tion.