An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 892

Fr.: anisotrope   

Describing a medium in which certain physical properties are different in different directions.

anisotropy; → -ic.

anisotropic homogeneous cosmological model
  مدل ِ کیهانشناختی ِ همگن و نا-ایزوگرد   
model-e keyhânšenâxti-ye hamgen o nâ-izogard

Fr.: modèle cosmiologique homogène mais anisotrope   

A solution to Einstein's theory of → general relativity that is spatially homogeneous but allows for rotation and/or shear. See also → Bianchi cosmological model.

anisotropic; → homogeneous; → cosmological; → model.

  ناهمسانگردی، نا-ایزوگردی   
nâhamsângardi, nâ-izogardi

Fr.: anisotropie   

A variation in a property with direction, e.g. → cosmic microwave background anisotropy, → dipole anisotropy.

From → an-, privative prefix, + → isotropy.

nâbudi (#)

Fr.: annihilation   

The process in which the entire → mass of → two colliding → particles, one of → matter and one of → antimatter, is → converted into → radiant energy in the form of → gamma rays. See also → annihilation operator.

L. annihilatus, p.p. of annihilare "to reduce to nothing," from ad- "to" + nihil "nothing," from ne- "not" + hilum "small thing, trifle"

Nâbudi, from nâ- "not" + bud "to be, exist," from budan "to be, exist" + -i noun forming suffix.

annihilation operator
  آپارگر ِ نابودی   
âpârgar-e nâbudi

Fr.: opérateur d'annihilation   

In → quantum field theory, the operator that lowers → eigenstates one → energy level, contrarily to the → creation operator.

annihilation; → operator.


Fr.: annoncer   

To make known publicly or officially; proclaim; give notice of (

M.E., from M.Fr. anoncer, O.Fr. anoncier "announce, proclaim," from L. annuntiare, adnuntiare "to announce, relate," literally "to bring news," from → ad- "to" + nuntiare "relate, report," from nuntius "messenger."

žâyidan, from prefix â- + Sogd., Munji žây- "to speak, to say," Yaghnobi žoy- "to read, sing," Yazghulami γay- "to call," Pers. (prefixed) afqân "lamentation, groaning;" Av. gā- "to sing," pairi.gā.vacah- "who sings the words around," bərəzi.gāθra- "singing high," gāθə- "song, gāthā;" cf. Skt. gā- "to sing;" O.Russ. gajati "to croak (ravens)"; Lith. giedoti "to sing" (Cheung 2007).


Fr.: annuel   

Covering the period of a year; occurring or happening every year or once a year.

Annual, from M.Fr. annuel, from L.L. annualis, blend of L. annuus "yearly," from annus "year" and L. annalis "yearly," from annus "year," from PIE *atnos, from *at- "to go" (Skt. a'tati "he goes, wanders").

Sâlâné, from sâl, → year, + âné "-ly".

annual aberration
  بیراهش ِ سالانه   
birâheš-e sâlâné

Fr.: aberration annuelle   

The apparent, small displacement in position of a star during the year due to the → aberration of starlight. It depends on the → celestial latitude, and its maximum value is about 20''.50. See also → constant of aberration; → aberration orbit.

annual; → aberration.

annual apparent motion
  جنبش ِ سالانه‌ی ِ پدیدار   
jonbeš-e sâlâne-ye padidâr

Fr.: mouvement annuel apparent   

annual motion.

annual; → apparent; → motion.

annual equation
  هموگش ِ سالانه   
hamugeš-e sâlâné

Fr.: équation annuelle   

An irregularity in the Moon's orbit, which can amount to 11 degrees in a period of one year. It results from the Sun's disturbing effect on the motion of the Moon due to varying distance between them.

annual; → equation.

annual motion
  جنبش ِ سالانه   
jonbeš-e sâlâné

Fr.: mouvement annuel   

The annual apparent motion of the → Sun in the sky with respect to → fixed stars along the path called → ecliptic. The apparent annual motion is due to the → Earth's → revolution about the Sun. In the course of this motion, the Sun appears to shifts about 1° eastward per day.

annual; → motion.

annual parallax
  دیدگشت ِ سالانه   
didgašt-e sâlâné

Fr.: parallaxe annuelle   

The difference in position of a star as seen from the → Earth and → Sun, i.e. the angle subtended at a star by the mean → radius of the Earth's orbit around the Sun. Same as → heliocentric parallax. Because the Earth revolves around the Sun, we observe the sky from a constantly moving position in space. Therefore, we should expect to see an annual effect, in which the positions of nearby objects appear to oscillate back and forth in response to our motion around the Sun. This does in fact happen, but the distances to even the nearest stars are so great that we need to make careful observations with a telescope to detect it. The annual parallax of the nearest star, → Proxima Centauri, is 0.762 arcsec, which is too small for our → acuity of vision.

annual; → parallax.

annual variation
  ورتش ِ سالانه   
varteš-e sâlâné

Fr.: variation annuelle   

Generally, the variation of a quantity over a year. In particular the yearly change in the right ascension or declination of a star, produced by the combined effects of the precession of the equinoxes and the proper motion of the star.

annual; → variation.


Fr.: annuler   

(Especially of laws or other established rules, usages, etc.) to make void or null; abolish; cancel; invalidate (

M.E., from O.Fr. anuller, from L.L. annullare "to make to nothing," from L. → ad- "to" + nullum, neuter of nullus "nothing," → null.

Ânulidan, from prefix â- + nul, → null, + -idan infinitive suffix.

  حلقه‌وار، حلقه‌ای   
halqevâr, halge-yi

Fr.: annulaire   

Having the form of a → ring.

From Fr. annulaire or directly from L. annularis "pertaining to a ring," from annulus, diminutive of anus "ring."

Halge-yi, halqevâr, adj. from halqé, → ring.

annular eclipse
  خورگرفت ِ حلقه‌وار   
xorgereft-e halqevâr

Fr.: éclipse annulaire   

A solar eclipse in which the Moon is close the → apogee and is, therefore, too small to cover the whole disk of the Sun, leaving a visible edge or ring of sunlight. An annular eclipse can last for 12m 30s at the most. See also → total eclipse.

annular; → eclipse.

annular-total eclipse
  خورگرفت ِ حلقه‌وار-هماک   
xorgereft-e halqevâr-hamâk

Fr.: éclipse annulaire-totale   

A solar eclipse that has both annular and total phases. Same as → hybrid eclipse.

annular; → total; → eclipse.


Fr.: annularité   

The maximum phase of an → annular eclipse during which the Moon's entire disk is seen silhouetted against the Sun. Annularity is the period between second and → third contact during an annular eclipse. It can last from a fraction of a second to a maximum of 12 minutes 29 seconds (F. Espenak, NASA).

annular; → -ity.

ânod (#)

Fr.: anode   

An → electrode from which a stream of → electrons leaves, as in an electron tube or electrolytic cell. → cathode.

From Gk. anodos "way up," from → ana- "up" + hodos "way."

Ânod, loanword from anode as above.

anomalistic month
  ماه ِ پیرازمینی   
mâh-e pirâzamini

Fr.: mois anomalistique   

The time interval of 27.554 551 days (27d 13h 18m 33.2s), on average, between two successive passages of the Moon through the → perigee of its orbit.

Anomalistic from → anomaly.

Pirâzamini from pirâzamin, → perigee.

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