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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 888
antipodal
  پادپایی   
pâdpâyi

Fr.: antipodal   

1) Of or relating to the → antipodes.
2) Describing two points when a line drawn from one to the other does not pass through the geometric centre of the Earth.

antipode; → -al.

antipode
  پادپای   
pâdpây

Fr.: antipode   

1) The exact or direct opposite.
2) Either or both of two points, places, or regions that are situated diametrically opposite to one another on the Earth's surface (Dictionary.com).

M.E., from L., from Gk. antipod-, antipous, literally "with feet opposite," from → anti- "against," + pod-, pous, → foot.

Pâdpây, from pâd-, → anti-, + pây, → foot.

antiproton
  پادپروتون   
pâdproton

Fr.: antiproton   

The antiparticle of a proton, identical in mass and spin but of opposite (negative) charge.

From → anti- + → proton.

antiquark
  پادکو‌آرک   
pâdkuârk

Fr.: antiquark   

The → antiparticle of a → quark.

anti-; → quark.

antisolar point
  نقطه‌ی ِ پادخورشیدی   
noqte-ye pâdxoršidi

Fr.: direction antisolaire   

Meteo.: The point on the → celestial sphere that lies directly opposite the Sun from the → observer, observer, that is, on the line from the Sun through the observer. The antisolar point is the center of the rainbow, and can be easily found on a sunny day: it it located at the shadow of one's head; it is 180° away from the Sun. If the Sun is in the sky, the antisolar point is below the horizon. If the Sun has set, the antisolar point is above the horizon.

anti-; → solar; → point.

antitail
  پاددم   
pâddom

Fr.: contre-queue   

A small tail-like structure on a comet that, unlike most comet tails, seems to point toward the Sun. This rare event is an optical illusion due to larger dust particles left along the comet's orbit. And typically occurs when the Earth crosses the plane of the comet's orbit. It seen when the observer is in the plane of the cometary orbit.

Antitail, from → anti- "opposite, opposing, against" + → tail.

Pâddom, from pâd-, → anti-, + dom "tail."

antithesis
  پاد-دایش   
pâd-dâyeš

Fr.: antithèse   

Logical or verbal opposition.
Philo. The second of two opposed propositions in Hegelian dialectic, the first of which is the → thesis; → synthesis.

anti-; → thesis.

antithetic
  پاد-دایشیک   
pâd-dâyešik

Fr.: antithétique   

1) Of the nature of or involving → antithesis.
2) Directly opposed or contrasted; opposite (Dictionary.com).

antithesis; → -ic.

Antlia
  تلمبه   
Tolombé (#)

Fr.: Machine pneumatique   

The Air Pump. A faint constellation in the southern hemisphere, at about alpha 10h, delta -35 deg. Abbreviation: Ant; genitive form: Antliae.

L. antlia "pump," from Gk. antlia "ship's hold, bilge water," from antlos.

Tolombé "pump," from Turkish tulumba "pump," from It. tromba.

Antoine equation
  هموگش ِ آنتوان   
hamugeš-e Antoine

Fr.: équation d'Antoine   

A mathematical expression, derived from the → Clausius-Clapeyron equation, of the relation between the vapor pressure and the temperature of pure substances. It shows that the logarithm of vapor pressure is linearly dependent on the reciprocal of → absolute temperature.

Named after Louis Charles Antoine (1825-?), a French marine engineer, who derived the equation; → equation.

antonym
  پادچم   
pâdcem

Fr.: antonyme   

Grammar: A word opposite in meaning to another.

From → anti- + (syn)onym, → synonym.

Pâdcem, from opâd-, → anti-, + cem, → meaning.

antumbra
  پادسایه   
pâdsâyé

Fr.: anti-ombre   

That part of the Moon's shadow that extends beyond the → umbra. It is similar to the → penumbra in that the Sun is only partially blocked by the Moon. From within the antumbra, the Sun appears larger than the Moon which is seen in complete silhouette. An → annular eclipse is seen when an observer passes through the antumbra (F. Espenak, NASA).

anti- + → umbra.

Ap star
  ستاره‌ی ِ Ap   
setâre-ye Ap

Fr.: étoile Ap   

A star of spectral type A in which lines of ionized metals and → rare-earth elements are abnormally enhanced. Such stars have unusually strong magnetic fields, thousands of times stronger than the Sun's typical surface field. Ap stars are generally slow rotators because of magnetic braking.

A for the spectral type, p for → peculiar; → star.

apastron
  اپاستار، اپاستاره   
apâstâr, apâsetâré

Fr.: apoastre   

The point at which a binary star is furthest from its companion.

Apastron, from Gk. ap-, → apo- + astron "star."

Apâstâr, apâsetâré, from apâ-, → apo-, + stâr, setâré, → star.

aperiodic damping
  میرایی ِ نادوره‌ای   
mirâyi-ye nâdowreyi

Fr.: amortissement apériodique   

A system in which the → damping is great enough to prevent oscillation.

Aperiodic, from → a- + periodic; + → damping.

aperture
  دهانه   
dahâné (#)

Fr.: ouverture   

The diameter of the main mirror in a reflecting telescope, the objective lens in a refracting telescope, the dish of a radio telescope, or the entry of an instrument such as spectrograph, photometer.

From L. apertura, from apertus, p.p. of aperire "to open, uncover," from PIE *ap-wer-yo- from *ap- "off, away" + base *wer- "to cover".

Ddahâné "an opening," from dahân "mouth," from Mid.Pers./Mod.Pers. zafar, Av. zafar, zafan "mouth," compare with Skt. jambha- "set of teeth, mouth, jaws," Ger. Kiefer "mouth".

aperture efficiency
  کار‌آیی ِ دهانه   
kârâyi-ye dahâné

Fr.: efficacité d'ouverture   

The ratio of the → effective aperture of a radio telescope to the true aperture.

aperture; → efficiency.

aperture photometry
  شیدسنجی ِ دهانه‌ای   
šidsanji-ye dahânéi

Fr.: photométrie d'ouverture   

Photometry using a diaphragm to isolate a small sky area, either directly with a focal-plane diaphragm, or with an image processing system.

aperture; → photometry.

aperture ratio
  وابر ِ دهانه   
vâbar-e dahâné

Fr.: rapport d'ouverture   

The ratio of the effective diameter of a lens or mirror to its focal length.

aperture; → ratio.

aperture stop
  دریچه‌ی ِ دهانه   
darice-ye dahâné

Fr.: diaphragme d'ouverture   

The diaphragm that limits the diameter of the axial light bundle allowed to pass through a lens.

aperture; → stop.

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