An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 424
geomagnetic storm
  توفان ِ زمین‌مغناتیسی، ~ زمین‌مغناتی   
tufân-e zamin-meqnâtisi, ~ zamin-meqnâti

Fr.: orage géomagnétique   

A violent disturbance of the Earth's magnetic field, distinct from regular diurnal variations, following a → solar flare or → coronal mass ejection.

geomagnetic; → storm.


Fr.: géomagnetsme   

A branch of geophysics concerned with the study of the Earth's → geomagnetic field, including its origin, spatial extent, and variations in time.

geo-; → magnetism.

hendesi (#)

Fr.: géométrique   

Of or pertaining to geometry or to the principles of geometry.

Adj. of → geometry

geometric albedo
  سپیدای ِ هندسی   
sepidâ-ye hendesi

Fr.: albedo géométrique   

A measure of the → reflectivity of a surface, especially of the solar system bodies (planets, satellites or asteroids). It is the ratio of a body's brightness at zero → phase angle to the brightness of a perfectly diffusing disk with the same position and apparent size as the body. Geometric albedo depends on the radiation wavelength. The bolometric geometric albedo refers to reflectivity in all wavelengths. Compare with the → Bond albedo.

geometric; → albedo.

geometric delay
  درنگ ِ هندسی   
derang-e hendesi

Fr.: retard géométrique   

One of the two factors contributing to → gravitational lensing time delay that arises from the fact that the bent trajectory is longer than the straight one. The other factor is due to the → Shapiro time delay.

geometric; → delay.

geometric horizon
  افق ِ هندسی   
ofoq-e hendesi

Fr.: horizon géométrique   

Where the apparent → sea horizon would be if there were no → atmospheric refraction.

geometric; → horizon.

geometric mean
  میانگین ِ هندسی   
miyângin-e hendesi (#)

Fr.: moyenne géométrique   

The middle term in a → geometric progression. Of two terms, the geometric mean is the square root of their product. For example, the geometric mean of 4 and 9 is ± 6. For a series of n terms, it is expressed as: (a1.a2. ... .an)1/n.

geometric; → mean.

geometric optics
  نوریک ِ هندسی   
nurik-e hendesi

Fr.: optique géométrique   

A branch of physics that deals with reflection and refraction of rays of light without reference to the wave or physical nature of light.

geometric; → optics.

geometric progression
  فرایازی ِ هندسی   
farâyâsi-e hendesi (#)

Fr.: progression géométrique   

A → sequence in which the ratio of a term to its predecessor is the same for all terms. In general, the nth term has the form ar(n-1), where n is a positive integer, and a and r are nonzero constants; r is called the ratio or common ratio. Also called → geometric sequence.

geometric; → progression.

geometric scattering
  پراکنش ِ هندسی   
parâkaneš-e hendesi

Fr.: diffusion géométrique   

A type of scattering in which the wavelength (of the light or the sound) is much smaller than the size of object causing the scattering.

geometric; → scattering.

geometric sequence
  پی‌آیه‌ی ِ هندسی   
peyâye-ye hendesi

Fr.: suite géométrique   

geometric progression.

geometric; → sequence.

geometrical libration
  رخگرد ِ هندسی   
roxgard-e hendesi (#)

Fr.: libration géométrique   

A lunar libration motion either in latitude resulting from the inclination of the Moon's orbit with respect to the ecliptic, or in longitude due to the elliptical shape of the Moon's orbit which causes a change in its aspect as seen from the Earth. → libration; → physical libration.

geometric; → libration.

hendesé (#)

Fr.: géométrie   

The branch of mathematics that deals with the nature of space and the size, shape, and other properties of figures as well as the transformations that preserve these properties.

From O.Fr. géométrie, from L. geometria, from Gk. geometria "measurement of earth or land," from → geo- + -metria, from metrein "to measure," → -metry.

Hendesé, Mid.Pers. handâxtan "to measure," Manichean Mid.Pers. hnds- "to measure," Proto-Iranian ham-, → com-, + *das- "to heap, amass;" cf. Ossetic dasun/dast "to heap up;" Arm. loanword dasel "to arrange (a crowd, people)," das "order, arrangement,"

zaminfizik (#)

Fr.: géophysique   

The branch of physics that deals with the Earth and its environment, including meteorology, oceanography, seismology, and geomagnetism.

geo-; → physics.


Fr.: géopolitique   

The study or the application of the influence of political and economic geography on the politics, national power, foreign policy, etc., of a state (

geo-; → politics.

geostationary orbit
  مدار ِ زمین‌ایست‌وّر   
madâr-e zamin-istvar

Fr.: orbite géostationnaire   

A satellite orbit in the plane of the Earth's equator and 35,880 km above it, at which distance the satellite's period of rotation matches the Earth's and the satellite always remains fixed in the same spot over the Earth.

Geostationary, from → geo- + → stationary; → orbit.


Fr.: géostrophique   

Of or pertaining to the force produced by the rotation of the Earth.

From Gk. → geo- + Gk. strophe "a turning," from strephein "to turn," from PIE *strebh- "to wind, turn" + → -ic.

From zamin-, → geo-, + carxeši, → rotational.

geostrophic balance
  ترازمندی ِ زمین‌چرخشی   
tarâzmandi-ye zamincarxeši

Fr.: équilibre géostrophique   

Meteo.: The balance between the → Coriolis force and the → pressure gradient force. See also → geostrophic flow.

geostrophic; → balance.

geostrophic flow
  تچان ِ زمین‌چرخشی   
tacân-e zamincarxeši

Fr.: écoulement géostrophique   

Oceanography: A flow resulting from → geostrophic balance. In geostrophic flow water moves along the lines of constant pressure or → isobars. Geostrophic flow is characterized by small → Rossby and → Ekman numbers.

geostrophic; → flow.

geostrophic wind
  باد ِ زمین‌چرخشی   
bâd-e zamincarxeši

Fr.: vent géostrophique   

Meteo.: A wind which is balanced by the → Coriolis effect and → pressure gradient force. An air parcel initially at rest will move from high pressure to low pressure because of the pressure gradient force. However, the air parcel in its movement is deflected by the Coriolis force, to the right in the northern hemisphere and to the left on the southern hemisphere. As the wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force. At this point, the wind will be blowing parallel to the → isobars.

geostrophic; → wind.

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