An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1251
Comet West (C/1975 V1)
  دنباله‌دار ِ وست، دمدار ِ ~   
donbâledâr-e West, domdâr-e ~

Fr.: comète West   

A spectacular comet that at its closest approach to Earth reached a brightness of -1 magnitude. It was so bright that could be seen even at sunrise. The comet reached → perihelion on 1976 Feb. 25 at 0.20 A.U. and had a fan-shaped tail of dimensions 25° x 25° x 15° on the sky. A few days after perihelion, the nucleus split in four fragments. The → carbon monoxide (CO) molecule in comets was first detected in West. The comet's orbit has a period of about 500,000 years. Formerly designated 1976 VI.

After the Danish astronomer Richard M. West (1941-), who worked at the → European Southern Observatory (ESO); → comet.

  دنباله‌دار؛ گیسوار   
donbâledâr; gisvâr

Fr.: cométaire   

Of or relating to or resembling a → comet.

comet; → -ary.

cometary activity
  ژیرندگی ِ دنباله‌دار   
žirandegi-ye donbâledâr

Fr.: activité cométaire   

The appearance of → gas and → dust features from the rocky-icy nucleus of a comet when approaching the Sun (→ cometary atmosphere, → cometary tail). The → sublimation of → water can explain cometary activity at distances from the Sun up to about 4 → astronomical units. At larger distances, the average temperature of the → comet nucleus' surface is less than 140 K, too low for efficient sublimation of water → ice. However, there are many examples of cometary activity at larger distances. This can probably be due to the sublimation of more → volatile → chemical species. Indeed, radio spectroscopic observations of comets at large distances have revealed an important → outgassing of → carbon monoxide (CO), which can sublimate at temperatures as low as 25 K.

cometary; → activity.

cometary atmosphere
  جو ِ دنباله‌دار، هواسپهر ِ ~   
javv-e donbâledâr, havâsepehr-e ~

Fr.: atmosphère de comète   

The envelope of → gas and → dust around a → comet nucleus, also known as → coma. As the comet approaches the → Sun, the frozen materials → sublimate and give rise to an expanding atmosphere. The atmosphere is composed of dust, → molecules, → radicals, and molecular → ions released from the inner coma with velocities ~ 0.5 to 1 km s-1, well above the → escape velocity for the nucleus. The → chemical species observed in cometary spectra can be divided into several categories: (i) atoms and molecules related to → water (H, O, OH, OH+, H2O, H2O+), (ii) carbon and related molecules (C, C+, CO, CO+, CO2+, C2, CH, CH+, HCO, H2CO), (iii) → nitrogen and related molecules (CN, CN+, HCN, CH3CN, NH, NH2, N2+, NH3, NH4), (iv) → sulphur and related molecules (S, CS, S2, H2S+), (v) → metals (Na, K, Ca, Co, Cr, Cu, V, Fe, Mn, Ni). For a typical average comet the neutral atmosphere is first seen when the heliocentric distance is d ≤ 3 → astronomical units.

cometary; → atmosphere.

cometary globule
  گویچه‌ی ِ گیسوار   
guyce-ye gisvâr

Fr.: globule cométaire   

A relatively small cloud of → dust and → gas in the → interstellar medium shaped like a comet with a bright-rimmed head. Cometary globules are situated near young → massive stars with a strong → stellar wind. The wind ionizes gases on the side facing the → O stars and sweep away the low-density gas toward the tail. Cometary globules are believed to be → molecular cloud condensations, which are so dense that they are not disrupted when an → H II region expands into the molecular cloud surrounding it. The → Rosette nebula is a good example of an H II region which shows an abundance of cometary globules.

comet; → globule.

cometary nucleus
  هسته‌ی ِ دنباله‌دار   
haste-ye donbâledâr (#)

Fr.: noyau cométaire   

comet nucleus.

cometary; → nucleus.

cometary orbit
  مدار ِ دنباله‌دار   
madâr-e donbâledâr

Fr.: orbite de comète   

The → path followed by a → comet in the → solar system around the → Sun. Most cometary orbits appear to be → elliptical, or in some cases → parabolic. The orbits of → short-period comets are elliptical, carrying them out to a region lying from → Jupiter to beyond the orbit of → Neptune. Those of → long-period comets are very elliptical. The orbits may be strongly influenced if they pass near the Jovian planets, particularly Jupiter itself. The cometary orbits are also influenced to some degree by gases shooting out of comets, so their orbits are primarily but not completely determined by gravity. Newton (1644-1727) was the first to compute a cometary orbit. He found that the comet of 1680 was following a parabolic orbit around the Sun. Edmond Halley (1656-1742), following the methods of Newton, computed the → orbital elements of 24 comets. He realized that the comets of 1531, 1607 and 1682 had very similar elements and postulated that they were in fact the same object, orbiting an elongated ellipse. He predicted the next return to occur in 1758 or early 1759. The return of what is now called Halley's comet was observed after his death, This first observation of a "predicted" comet is manifestly one of the major successes of → celestial mechanics.

cometary; → orbit.

cometary tail
  دم ِ دنباله‌دار   
dome- donbâledâr

Fr.: queue de comète   

A formation of → gas and/or → dust that streams away from the → coma of many comets under the influence of the Sun's → radiation pressure and the → solar wind. See also: → dust tail, → gas tail, → ion tail, → plasma tail, → sodium tail, → Type I tail, → Type II tail, → antitail.

cometary; → tail.

  هم مسا   

Fr.: commensurable   

(adj.) Of the same size, extent, or duration as another; proportionate.

L.L. commensuratus, from → com- "together, with" + mensuratus, p.p. of mensurare "to measure," from menusra "measure."

Hammasâ, from ham- "together," → com- + masâ "size, greatness," from Mid.Pers. masây, masâk "size," Av. masah- "size, greatness, length," maz-, masan-, mazant- "great, important," mazan- "greatness, majesty," mazišta- "greatest," cf. Skt. mah-, mahant-, Gk. megas, L. magnus; PIE *meg- "great."

commensurate orbits
  مدارها‌ی ِ هم مسا   
madârhâ-ye hammasâ

Fr.: orbites commensurables   

Of two bodies orbiting around a common barycenter, when the orbital period of one is an exact fraction, for example one-half or two-thirds, of the other.

commensurate; → orbit.

  ۱) هامت؛ ۲) هامتیدن   
1) hâmat; 2) hâmatidan

Fr.: commentaire   

1a) A remark, observation, or criticism (
1b) A note in explanation, expansion, or criticism of a passage in a book, article, or the like; annotation (
2) To make remarks, observations, or criticisms (

M.E. coment, from O.Fr. coment "commentary;" L.L. commentum "comment, interpretation," in classical L. "invention, fiction," from comminisci "to contrive, devise," from → com-, intensive prefix + base of meminisse "to remember," related to mens, → mind.

Hâmat, from hâ-, intensive prefix, variant of ham-, → com-, + mat- "think; thought," from Av. mat- matay- "to think," humat- "good thought;" cf. Skt. matāy-.


Fr.: commentaire   

1) A series of comments, explanations, or annotations (
2) An explanatory essay or treatise (

From M.E. commentaries (plural), from L. commentarium "notebook," noun use of neuter of commentarius, from comment(um), → comment, + -arium, → -ary.

Hâmatgân, from hâmat, → comment, + gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna.


Fr.: commenter   

To deliver, to write a → commentary on.

Verb from → comment.


Fr.: commentateur   

1) A person who makes commentaries.
2) A person who discusses news, sports events, weather, or the like, as on television or radio.

Agent noun from → commentate.

  راه اندازش   

Fr.: rodage   

Putting a telescope or an observing instrument into active service after their final construction.

From L. commissionem "delegation of business," from commissus, p.p. of committere "to bring together," from → com- "together" + mittere "to put, send."

Râhandâzeš, verbal noun from compound verb râhandâxtan "to set in work; to prepare," from râh "way, path" + andâxtan "to cast; to make, do; to throw."

commissioning period
  دوره‌ی ِ راه اندازش   
dowre-ye râhandâzeš

Fr.: période de rodage   

A period during which a newly constructed observing instrument is used for test.

commissioning; → period.


Fr.: commun   

Belonging to or shared by two or more or all in question. → common denominator, → least common multiplier.

From M.E. comun, from O.Fr. comun, from L. communis "in common, public, general, shared by all or many," originally "sharing common duties," akin to munia "duties, public duties, functions," from munus "task, duty, gift."

Hamdâr, literally "possessing together, sharing together," from ham-, → com-, + dâr present stem of dâštan "to have, to possess," from 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."

common denominator
  نامان ِ همدار   
nâmân-e hamdâr

Fr.: dénominateur commun   

A quantity into which all the denominators of a set of fractions may be divided without a remainder.

common; → denominator.

common fraction
  برخه‌ی ِ همدار   
barxe-ye hamdâr

Fr.: fraction d'entiers   

A fraction written as a/b where a and b are → positive  → integers, as opposed to a → decimal fraction; for example, 5/7. Common fractions are sometimes also called → vulgar fractions.

common; → fraction.

common logarithm
  لگاریتم ِ دهدهی   
logâritm-e dahdahi

Fr.: logarithme décimal   

The logarithm with → base 10. It is known also as the → decimal logarithm, decadic logarithm, or Briggsian logarithm, after Henry Briggs, an English mathematician who pioneered its use.

common; → logarithm; → decimal.

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