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: 399
geocentric system
  راژمان ِ زمین‌مرکزی   
râžmân-e zamin-markazi

Fr.: système géocentrique   

An ancient model of the Universe whereby all the celestial bodies travel around the Earth in circular orbits. Eudoxus of Cnidus (c. 390- c. 337 BC), one of Plato's pupils, maintained that all objects in the sky are attached to moving crystalline spheres, with the Earth at the centre. This model is often named → Ptolemaic system after its most famous supporter, the Greco-Roman astronomer Ptolemy.

geocentric; → system.

geocorona
  زمین‌تاج   
zamin-tâj (#)

Fr.: géocouronne   

The outermost part of Earth's atmosphere, a tenuous halo of hydrogen and some helium extending out to perhaps 15 Earth radii, which emits Lyman-alpha radiation when it is bombarded by sunlight.

From → geo- + → corona.

geodesic
  کهین‌ره، زمین‌سنجیک   
kehinrah, zamin-sanjik

Fr.: géodésique   

1) The shortest distance between two points in space (or → space-time). A geodesic on a sphere is an → arc of a → great circle. In the theory of → general relativity, freely falling bodies follow geodesic paths in space-time.
2) → geodetic.

From Fr. géodésique, → geodesy; → -ic.

Kehinrah "shortest path," from kehin, superlative of keh "small, little, slender" (related to kâstan, kâhidan "to decrease, lessen, diminish," from Mid.Pers. kâhitan, kâstan, kâhênitan "to decrease, diminish, lessen;" Av. kasu- "small, little;" Proto-Iranian *kas- "to be small, diminish, lessen") + râh "path, way, road" (from Mid.Pers. râh, râs "way, street," also rah, ras "chariot;" from Proto-Iranian *rāθa-; cf. Av. raθa- "chariot;" Skt. rátha- "car, chariot," rathyā- "road;" L. rota "wheel," rotare "to revolve, roll;" Lith. ratas "wheel;" O.H.G. rad; Ger. Rad; Du. rad; O.Ir. roth; PIE base *roto- "to run, to turn, to roll").

geodesic line
  خط ِ کهین‌ره   
xatt-e kehinrah

Fr.: ligne géodésique   

The shortest line between two points on a surface. Also called → geodesic.

geodesic; → line.

geodesic precession
  پیشایان ِ کهین‌رهی   
pišâyân-e kehinrahi

Fr.: précession géodésique   

geodesic precession.

geodesic; → precession

geodesy
  زمین‌سنجی   
zamin-sanji (#)

Fr.: géodésie   

The study and measurement of the shape, size, and curvature of the Earth.

From Fr. géodésie, from Gk. geodaisia, from → geo- + dai(ein) "to divide" + -sia, variant of -ia a noun suffix.

Zamin-sanji, from zamin, → geo-, + sanji, from sanjidan "to measure; to compare," from Mid.Pers. sanjidan "to weigh," from present tense stem sanj-, Av. θanj- "to draw, pull;" Proto-Iranian *θanj-. Other terms from this base in Pers.: lanjidan "to pull up," hanjidan, âhanjidan "to draw out," farhang "education, culture."

geodesy satellite
  ماهواره‌ی ِ زمین‌سنجی، ~ زمین‌سنجیک   
mâhvâre-ye zamin-sanji, ~ zamin-sanjik

Fr.: satellite géodésique   

A type of Earth observing satellite used to measure the location of points on Earth's surface with great accuracy. Their observations help determine the exact size and shape of Earth, act as references for mapping, and track movements of Earth's crust.

geodesy; → satellite

geodetic
  زمین‌سنجیک   
zamin-sanjik

Fr.: géodésique   

Of, relating to, or determined by → geodesy.

geodesy; → -ic.

geodetic coordinates
  هماراهای ِ زمین‌سنجیک   
hamârâhâ-ye zamin-sanjik

Fr.: coordonnées géodésiques   

A → coordinate system, composed of → geodetic latitude and → geodetic longitude on the → Earth's surface which is dependent on the figure and size of a particular model for the Earth's surface.

geodetic; → coordinate.

geodetic datum
  داده‌بن ِ زمین‌سنجیک   
dâdebon-e zamin-sanjik

Fr.: donnée géodésique   

Any of the adopted values of → geodetic latitude, → geodetic longitude, or → azimuth at a selected location (an initial station) whose astronomical coordinates have already been determined.

geodetic; → datum.

geodetic equator
  هموگار ِ زمین‌سنجیک   
hamugâr-e zamin-sanjik

Fr.: équateur géodésique   

The plane swept out as the generating ellipse of the → reference ellipsoid rotates about its minor axis.

geodetic; → equator.

geodetic latitude
  ورونای ِ زمین‌سنجیک   
varunâ-ye zamin-sanjik

Fr.: latitude géodésique   

The → acute angle between the → geodetic vertical and the → geodetic equator.

geodetic; → latitude.

geodetic longitude
  درژنای ِ زمین‌سنجیک   
derežnâ-ye zamin-sanjik

Fr.: longitude géodésique   

The angle between the plane of the → geodetic meridian and the plane of of the geodetic meridian through the site of the → Airy transit circle at the Royal Greenwich Observatory.

geodetic; → longitude.

geodetic meridian
  نیمروزان ِ زمین‌سنجیک   
nimruzân-e zamin-sanjik

Fr.: méridien géodésique   

The → ellipse through the point in question which passes through the → geodetic poles.

geodetic; → meridian.

geodetic parallel
  پراسوی ِ زمین‌سنجیک   
parâsu-ye zamin-sanjik

Fr.: parallèle géodésique   

Any of the small circles on the → reference ellipsoid parallel to the → geodetic equator.

geodetic; → parallel.

geodetic pole
  قطب ِ زمین‌سنجیک   
qotb-e zamin-sanjik

Fr.: pôle géodésique   

Any of the interaction points of the axis of revolution of the → reference ellipsoid with its surface.

geodetic; → pole.

geodetic precession
  پیشایان ِ کهین‌رهی   
pišâyân-e kehinrahi

Fr.: précession géodésique   

A → relativistic effect on the precession motion of a gravitational system due to the → curvature of the → space-time. When a body revolves around a primary, the → rotation axis of the orbiting body follows the curvature of spece-time. Over time the space-time warping causes the spin axis to precess. In the case of the Earth-Moon system, this means a small → direct motion of the → equinox along the → ecliptic, amounting to 1''.915 per century. The geodetic precession is given by: ψg = (3/2) k2 (1 - e) n, where k is the → constant of aberration (in radians), e the → eccentricity of the Earth and n the mean angular orbital motion of the Earth (in arcsec/cy). Also called → Einstein-de Sitter effect and → geodesic precession.

geodetic; → precession

geodetic refraction
  شکست ِ زمین‌سنجیک   
šekast-e zamin-sanjik

Fr.: réfraction géodésique   

The limiting case of → astronomical refraction when the light path is entirely within the Earth's atmosphere.

geodetic; → refraction.

geodetic vertical
  هجین ِ زمین‌سنجیک   
hajin-e zamin-sanjik

Fr.: vertical géodésique   

The direction defined by the → normal to the → reference ellipsoid at the point in question.

geodetic; → vertical.

geodetic zenith
  سرسوی ِ زمین‌سنجیک   
sarsu-ye zamin-sanjik

Fr.: zénith géodésique   

The intersection of the prolongation of the outward → normal to the → reference ellipsoid at the point in question with the → celestial sphere.

geodetic; → zenith.

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