An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 663

Fr.: ellipticité   

The degree of divergence of an ellipse from a circle.

From elliptic-, from elliptical + → -ity.

Beyzigi, from beyzi, → ellipse, + -igi, → -ity.

Elnath (β Tau)
  ناطح، شاخزن   
Nâteh (#), šâxzan (#)

Fr.: Alnath   

Same as → Alnath.



Fr.: allonger   

To draw out to greater length; lengthen; extend.

From L.L. elongatus "lengthened out," p.p. of elongare "to make longer, to remove to a distance," from → ex- "out" + longus "long;" PIE base *dlonghos- "long;" cf. Av. darəga-, darəγa- "long," drājištəm "longest;" Mod.Pers. derâz "long," dir "late; long;" Skt. dīrghá- "long (in space and time);" Gk. dolikhos "long;" P.Gmc. *langgaz (Ger. lang; O.N. langr; M.Du. lanc; Goth. laggs "long;" E. long).

DerâzidanDerâzeš "to elongate," from derâz "long," Mid.Pers. drâz "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" PIE *dlonghos- "long," as above.

  درازیده، کشیده   
derâzidé, kešidé

Fr.: allongé   

Made longer; long and narrow.

Past participle of → elongate.

elongated orbit
  مدار ِ کشیده، ~ درازیده   
madâr-e derâzidé, ~ kašidé

Fr.: orbite allongée   

An → elliptical orbit with a high → eccentricity.

elongated; → orbit.


Fr.: élongation   

1) Increase in length per unit of original length.
2) The angular distance of a planet from the Sun as seen from the Earth. An elongation of 0° is called → conjunction; one of 180° is called → opposition; and an elongation of 90° is called → quadrature.

elongate; → -tion.

Elsasser number
  عدد ِ الزسر   
adad-e Elsasser

Fr.: nombre d'Elsasser   

A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → Lorentz forces to → Coriolis forces. It is given by: Λ = σB2/(ρΩ), where σ s the → electrical conductivity of the fluid, B is the typical → magnetic field strength within the fluid, ρ is the fluid → density, and Ω is the → angular velocity. A typical value for the Earth is Λ ~ 1.

Named after Walter Maurice Elsasser (1904-1991), American theoretical physicist of German origin; → number.

Eltanin (Gamma Draconis)
Tannin (#)

Fr.: Eltanin   

The brightest star in the constellation → Draco, with a visual magnitude of V = 2.23 and color B - V +1.52. It is a cool (4000 K) → giant star of spectral Type K5 III, lying 148 → light-years. Gamma Draconis has a luminosity 600 times that of the Sun and a diameter 50 times that of the Sun. It crosses the sky near the zenith point for England, a nd this was the reason why James Bradley (1693-1762) observed γ Draconis when he was trying to detect parallax and so calculate the distance. He found that the star undergoes a yearly shift of a form quite different from that expected from parallax. In a 1728 paper, Bradley announced his discovery and explained the effect as due to the → aberration of starlight . Variant names: Etamin, Etanin; Ettanin, other designations: HR 6705, HD 164058.

From Ar. At-Tinnin (التنین) "the great serpent," the Ar. rendition of the Greek constellation → Draco.


Fr.: elfe   

A transient upper atmospheric phenomenon occurring over a → thunderstorm in the lower → ionosphere. Elves result from especially powerful electromagnetic radiation pulses that are generated from certain lightning discharges (→ sprite). As the energy passes upwards through the base of the ionosphere it causes the gases to briefly glow for less than a thousandth of a second. This makes elves virtually impossible to see with the naked eye. Elves occur at a height of around 90-95 km, and can expand outward to several hundred kilometers in diameter, like giant expanding doughnuts.

Short for: Emission of Light and Very low-frequency perturbations from Electromagnetic pulse sources.

From E. elf "(in folklore) a small often malicious fairy; goblin; sprite;" O.E. elf, ælf, ylfe; cf. O.S. alf, O.N. alfr, Ger. alp, of unknown origin.

runemudan (#)

Fr.: émaner   

To flow out, issue, or proceed, as from a source or origin; come forth; originate; arise (

From L. emanatus, p.p. of emanare "flow out," figuratively "arise from, proceed from."

Runemudan "to appear, come out," literally "to show face," from ru "face," → surface, + nemudan "to show," → display.

runemud (#)

Fr.: émanation   

An act or instance of emanating; something that emanates or is emanated.

emanate; → -tion.

embedded star
  ستاره‌ی ِ فروپوشیده   
setâre-ye forupušidé

Fr.: étoile enfouie   

A newborn star which is tightly enveloped by a surrounding cloud of gas and dust.

Ebedded p.p. of embed, from en- + bed from O.E. bed "bed," from P.Gmc. *badjam "sleeping place dug in the ground" (O.H.G. betti; Ger. bett); PIE base *bhedh- "to dig, pierce;" cf. Gk. bothyros "pit;" L. fodere "to dig," fossa "ditch;" → star.

Setâré, → star; forupušidé, p.p. of forupušidan, from foru- "below; beneath; down, downwards;" Mid.Pers. frôt "down, downwards;" O.Pers. fravata "forward, downward;" Skt. pravát- "a sloping path, the slope of a mountain" + pušidan "to cover, conceal, clothe; to wear clothes;" Mid.Pers. pôšidan, pôš- "to cover, put on, wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover;" Proto-Indo-Iranian *pauastā- "cloth."


Fr.: incarnation, incorporation, personnification   

The act of embodying; the state or fact of being embodied.

verbal noun of → embody.


Fr.: exprimer, concrétiser, incarner   

1) To give a concrete form or body to an idea or quality.
2) To cause to become a body or part of a body.

From en- "in" + → body

Tanigândan, from Mid.Pers. tanig "bodily, corporal," from tan "body," → if and only if, + -ig, → -ik, + -ândan suffix of transitive verbs.

embolismic month
  بهیزک، ماه ِ بهیزکی   
behizak (#), mâh-e behizaki (#)

Fr.: mois embolismique   

1) In several → lunisolar calendars, an → intercalary month employed to preserve a seasonal relationship between the Lunar and Solar cycles. For example, in the → Hebrew calendar the extra month, called Adar Alef, was inserted after Shvat so that the month of Nissan (month of spring) does not begin in winter.
2) In ancient Iranian → solar calendar the additional whole month of 30 days employed every 120 years to compensate for the left-over quarters of days in a calendar year of 365 days (120 years × 0.25 days = 30 days).

M.E. embolisme, from M.L. embolismus "intercalation," from Gk. emballein "to throw into, to insert," from em- "in" + ballein "to throw" (source of the medical term embolism "the obstruction (of an artery, etc.) by a clot of blood, bubble of air, etc."); → month.

Behizak, from Mid.Pers. vihezagig or vihezakik "movable," from vihezag "movement, progression," from vihez- "to move, progress;" mâh, → month.

embolismic year
  سال ِ بهیزکی   
sâl-e behizaki (#)

Fr.: année embolismique   

In ancient calendars, a year that contains an → embolismic month.

embolismic month; → year.


Fr.: émerger   

1) Move out of or away from something and become visible.
2) To rise or come forth from or as if from water or other liquid (

ex-, + merge, → submerge.


Fr.: émergence   

1) The process of becoming visible after being concealed.
2) The escape of an insect or other invertebrate from an egg, cocoon, or pupal case.
3) The process of coming into existence or prominence (

emerge; → -ence.


Fr.: émergent   

1) Coming into being or notice.
2) Philo.: (of a property) arising as an effect of complex causes and not analyzable simply as the sum of their effects.
3) Ecology: Of or denoting a plant which is taller than the surrounding vegetation, especially a tall tree in a forest (

emerge; → -ent.

emergent ray
  پرتو ِ زمرچنده   
partow-e zomarcandé

Fr.: rayon émergent   

Optics: The → light ray leaving a → medium, in contrast to the → incident ray. If the medium has parallel sides, → angle of incidence and → angle of emergence

emergent; → ray.

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