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

Construction of mathematical functions whose graphs are curves that "best" approximate a given collection of data points.

→ curve; → fitting.

Use of appropriate techniques to estimate the age of geological specimens or astronomical objects such as meteorites.

Verbal noun of date, from O.Fr. date, from M.L. → data.

Sen yâbi, from Ar. sen "age" + yâbi verbal noun of 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."

Of a spacecraft, the act or process of departing from an operational orbit. → de-orbit.

Noun form of → de-orbit.

A system characterized by → differential rotation. In such a system the → angular velocity decreases as the distance from the rotation center increases.

→ differential; → rotating; → system.

An optical device containing thousands of very fine parallel grooves which produce interference patterns in a way which separates out all the components of the light into a spectrum.

→ diffraction; → grating.

A break in sequence or continuity of anything. → Balmer discontinuity
Math.: A point at which a function is not continuous.
Geology: A surface separating rock layers of differing properties or compositions.

M.L. discontinuitas, from discontinuus, from → dis- + continuus, → continuous.

Nâpeyvastegi, noun from nâpeyvasté "discontinuous," from nâ- "non, un-," → a-, + peyvasté, → continuous.

1) Readily distinguishable from all others.
2) Clearly defined; unquestionable (TheFreeDictionary.com).

Past-participle adjective from obsolete distincten "to distinguish one thing from another; make distinct," from O.Fr. distincter, from L. distinctus, p.p. of distinguere "to separate between, mark off."

Bažnâ, literally "high," from Kurd. bažn "height, stature," variants baž, baš "height," bašn, → stature, faš, baš "a horse's mane."

1) The act or an instance of distinguishing or differentiating.
2) A distinguishing feature.
3) The state of being different or distinguishable.
4) Special honor, recognition, or fame (The FreeDictionary.com).

→ distinct; → -tion.

Serving to identify; distinguishing or characteristic.

→ distinct; → -ive.

In a clear and noticeable way; clearly.

→ distinct; → -ly.

The state or quality of being distinct.

→ distinct; → -ness.

1) To perceive as being different or distinct.
2) To demonstrate or describe as being different or distinct.

ME. distingwen, from O.Fr. distinguer, from L. distinguere "to separate between, divide, mark off," perhaps literally "separate by pricking," from assimilated form of → dis- "apart" + -stinguere "to prick."

Bažnâyidan, verb from bažnâ, → distinct.

1) Characterized by excellence or distinction; eminent.
2) Dignified in conduct or appearance (TheFreeDictionary.com).

Past participle of → distinguish.

A → transparent → crystalline substance (such as calcite, quartz, and tourmaline) that is → anisotropic relative to the → speed of light. A ray incident normally on such crystals is broken up into two rays in traversing the crystal, → ordinary ray and → extraordinary ray.

→ doubly; → refracting; → crystal.

A diffraction grating in which the groves are relatively widely spaced and serves to provide high resolution and dispersion.

Echelle, from Fr. échelle "ladder," , from O.Fr. eschele, from L. scala "ladder;" → grating.

Turi, → grating; nardé, contraction of nardebân "ladder; échelle."

The floor below a telescope used to lift observers to the level of the telescope's eyepiece, since the telescope is tilted at varying angles when it is in use.

Elevating, adj. of → elevate; → floor.

A method of mounting a telescope in which the polar axis is supported at each end by two piers. The great defect of this type of mounting is its inability to observe the pole.

→ mounting.

A telescope mounting consisting of a polar axis pointed toward the celestial pole, and a declination axis supporting the instrument at right angles to the polar axis.

→ equatorial; → mounting.

A star associated with an interstellar ionized nebula (→ H II region or → planetary nebula) whose energetic → ultraviolet, → photons → ionize the nebula.

Exciting, verbal adj. of → excite; → star.

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."