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

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.

Of, pertaining to, or dealing with the space beyond the Milky Way.

From → extra- + → galactic.

The branch of astronomy that deals with objects beyond the Milky Way, especially galaxies and quasars.

→ extragalactic; → astronomy.

The integrated intensity of all of the light emitted throughout the history of the Universe across the whole of the → electromagnetic spectrum, including those which are not individually detected. The EBL spectrum includes cosmological backgrounds associated with either primordial phenomena, such as the → cosmic microwave background radiation (CMBR), or photons emitted by stars, galaxies and → active galactic nuclei (AGN) due to → nucleosynthesis or other → radiative processes, including → dust scattering, → absorption and reradiation. The EBL may also contain signals that are diffuse and extended, including high-energy photons associated with dark matter particle decays or annihilation.

→ extragalactic; → background; → light.

1) Beyond what is usual, ordinary, regular, or established.
2) Exceptional in character, amount, extent, degree, etc. (Dictionary.com). → unordinary.

→ extra-; → ordinary.

When a beam of → unpolarized light is incident on a → doubly refracting crystal, there will be two refracted rays. The ray for which → Snell's law does not hold.

→ extraordinary; → ray.

Math.: To estimate the value of a result outside the range of a series of known values.

From → extra- + (inter)polate, → interpolate.

From borun, → extra- + yâftan, yâbidan "to find, discover; to obtain, acquire;" Mid.Pers. ayâftan, ayâpênitan "to reach, attain;" Manichean Mid.Pers. 'y'b "to attain;" Parthian, Sogdian (+ *pati-) pty'b "to reach, obtain;" Av. ap- "to reach, overtake," apayeiti "achieved, reached;" Skt. âp- "to reach, gain," âpnoti "reaches, gains;" Gk. hapto, haptomai "to touch, cling to, adhere to;" L. apiscor "touch, reach;" PIE base *ap- "to take, reach."

Predicting the value of unknown data points by projecting a function beyond the range of known data points.

Verbal noun of → extrapolate.

Not belonging to the → solar system; outside, or originating outside, the solar system.

→ extra-; → solar.

A planet which belongs to a star other than → Sun, and therefore does not belong to our → solar system; same as → exoplanet.

→ extrasolar; → planet.

A → planatary system around a star other than the Sun. Same as → exoplanetary system .

→ extrasolar; → system.

1) (adj.) Of or from outside the limits of the Earth.
2) (n.) A hypothetical extraterrestrial being; → alien.

→ extra- + → terrestrial.

Life that may exist and originate outside the planet Earth.

→ extraterrestrial; → life.

Farthest from the center or middle; outermost; exceeding the bounds of moderation. → extreme adaptive optics; → extreme HB star; → extreme horizontal branch star; → extreme infrared; → extreme mass ratio inspiral; → extreme ultraviolet; → extremely metal-poor star.

From L. extremus "outermost, utmost," superlative of exterus, "outer," comparative of ex "out of," → ex-.

Ostom "outermost, utmost" (Av. (ustəma- "outermost, highest, ultimate"), superlative of ost "out," → ex-, + -tom superlative suffix, from Mid.Pers. -tom (xwaštom "most pleasant," nevaktom "best," wattom "worst"), from O.Pers. -tama- (fratama- "first, front"); Av. -təma- (amavastəma- "strongest," hubaiδitəma- "most sweet-scented," baēšazyôtəma- "most healing," fratəma- "first, front"); cf. Skt. tama-.

An → adaptive optics system with high-contrast imaging and spectroscopic capabilities. Extreme adaptive optics systems enable the detection of faint objects (e.g., → exoplanets) close to bright sources that would otherwise overwhelm them. This is accomplished both by increasing the peak intensity of point-source images and by removing light scattered by the atmosphere and the telescope optics into the → seeing disk.

→ extreme; → adaptive; → optics.

Same as → extreme horizontal branch star.

→ extreme horizontal branch star.