An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 40 Search : side
apparent sidereal day
  روز ِ اختری ِ پدیدار   
ruz-e axtari-ye padidâr

Fr.: jour sidéral apparent   

The time interval between two successive → upper transits of the → true equinox of date.

apparent; → sidereal; → day.

apparent sidereal time
  زمان ِ اختری ِ پدیدار   
zamân-e axtari-ye padidâr

Fr.: temps sidéral apparent   

The → mean sidereal time corrected for the → nutation and shift in the obliquity of the ecliptic that occurs as a result of the Moon's gravitational effect. Apparent sidereal time differs from mean sidereal time in that the → true vernal equinox point is used.

apparent; → sidereal; → time.

apsides, line of
  خط ِ هباک‌ها   
xatt-e habâkhâ

Fr.: ligne des apsides   

The line connecting the two apsides, i.e. the major axis of an elliptical orbit. → apsis.

Apsides, pl. of → apside; → line.

apsis (pl. apsides)
  هباک   
habâk

Fr.: apside   

The point of greatest or least distance of the orbit of a celestial body from a center of attraction. The closest point is the → periapsis, the further point the → apoapsis.

L. apsis "arch, vault," from Gk. hapsis "loop, arch," from haptein "fasten together".

Mod.Pers. habâk "top of the head; the summit of a mountain".

consider
  آگاریدن   
âgâridan

Fr.: considérer   

To think carefully about, especially in order to make a decision; contemplate; reflect on (dictionary.com).

M.E. consideren, from O.Fr. considerer "reflect on, study," from L. considerare "to examine, look at closely," literally "to observe the stars," from → com- "with" + sider (stem of sidus) "star, group of stars," → sideral.

Âgâridan, from intensive prefix â- + gâr-, variants gar-, gâl- "to consider, observe," as in engâridan "to suppose," negaristan "to observe, look, notice," segâl "thought," segâlidan "to think, meditate," ultimately from Proto-Iranian *kar- "to observe, to consider;" cf. Av. kar- "to remember; to impress on memory;" Skt. kal- "to observe, consider," kalayati "considers, observes."

considerable
  آگاریدنی   
âgâridani

Fr.: considérable   

1) Rather large or great in size, distance, extent, etc.
2) Worthy of respect, attention, etc.; important; distinguished (dictionary.com).

consider; → -able.

consideration
  آگارش   
âgâreš

Fr.: considération   

The act or an instance of considering.

consider; → -tion.

Greenwich Apparent Sidereal Time (GAST)
  زمان ِ اختری ِ پدیدار ِ گرینویچ   
zamân-e axtari-ye padidâr-e Greenwich

Fr.: temps sidéral apparent de Greenwich   

The → Greenwich Mean Sidereal Time corrected for → nutation. Therefore, it is measured with respect to the → true vernal equinox. GAST and GMST differ by the → equation of the equinoxes.

Greenwich Meridian; → apparent; → sidereal; → time.

Greenwich Mean Sidereal Time (GMST)
  زمان ِ اختری ِ میانگین ِ گرینویچ   
zamân-e axtari-ye miyângin-e Greenwich

Fr.: temps sidéral moyen de Greenwich   

The → sidereal time related to the angle between the → prime meridian and the → mean vernal equinox, measured in the plane of the equator.

mean; → Greenwich Meridian; → sidereal; → time.

Greenwich sidereal date
  روز ِ اختری ِ گرینویچ   
ruz-e axtari-ye Greenwich

Fr.: jour sidéeal de Greenwich   

The number and fraction of → mean sidereal days elapsed on the → Greenwich meridian since 12h January 1, 4773 BC (mean sidereal).

Greenwich meridian; → sidereal; → date.

Greenwich sidereal day number
  شماره‌ی ِ روز ِ اختری ِ گرینویچ   
šomâre-ye ruz-e axtari-ye Greenwich

Fr.: nombre du jour sidéral de Greenwich   

The integral part of the → Greenwich sidereal date.

Greenwich; → sidereal; → day; → number.

Heaviside layer
  لایه‌ی ِ هه‌وی‌ساید   
lâye-ye Heaviside (#)

Fr.: couche de Heaviside   

Kennelly-Heaviside layer.

English physicist Oliver Heaviside (1850-1925).

Kennelly-Heaviside layer
  لایه‌ی ِ کنلی-هوی‌ساید   
lâye-ye Kennelly-Heaviside (#)

Fr.: couche de Kennelly-Heaviside   

One of several layers in the Earth's ionosphere occurring at 90-150 km above the ground. It reflects medium-frequency radio waves whereby radio waves can be propagated beyond the horizon.

Named after the American electrical engineer Arthur Edwin Kennelly (1861-1939) and the English physicist Oliver Heaviside (1850-1925), who independently predicted the existence of the reflecting layer in 1902; → layer.

line of apsides
  خط ِ هباک‌ها   
xatt-e habâkhâ

Fr.: ligne des apsides   

Of an elliptical orbit, the straight line drawn from the → perigee to the → apogee.

line, → apsides.

local sidereal time
  زمان ِ اختری ِ محلی   
zamân-e axtari-ye mahali

Fr.: temps sidéral local   

Local time measured by the apparent motion of the stars. It is the most useful form of sidereal time since it gives the right ascension of a transiting celestial object at a given location.

local; → sidereal; → time.

mean sidereal day
  روز ِ اختری ِ میانگین   
ruz-e axtari-ye miyângin

Fr.: jour sidéral moyen   

The average time interval between two successive → upper transits of the → mean equinox.

mean; → sidereal; → day.

mean sidereal time
  زمان ِ اختری ِ میانگین   
zamân-e axtari-ye miyângin (#)

Fr.: temps sidéral moyen   

The hour angle of the mean equinox for a given observer.

mean; → sidereal; → time.

mesosiderite
  مسوسیدریت   
mesosiderit

Fr.: mesosidérite   

A class of → meteorites that is → brecciatedstony-iron with nearly equal amounts of → metal and → silicates.

meso-; → siderite.

preside
  فرنشتیدن   
farneštidan

Fr.: présider   

To occupy the place of authority or control, as in an assembly or meeting; act as president or chairperson (Dictionary.com).

pre-; → reside.

president
  فرنشتگار   
farneštgâr

Fr.: président   

1) The highest executive officer of a modern republic, as the Chief Executive of the United States (often initial capital letter).
2) An officer appointed or elected to preside over an organized body of persons (Dictionary.com).

preside; → -ent.

Farneštgâr, from farnešt, present stem of farneštidan, → preside, + agent noun suffix -gâr, → -or, on the model of âmuzgâr "teacher."

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