An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 87 Search : plane
plane figure
  شکل ِ هامن، ~ تخت   
šekl-e hâmon, ~ taxt

Fr.: figure plane   

A two-dimensional geometric figure. The points of the figure lie entirely in a plane.

plane; → figure.

plane mirror
  آینه‌ی ِ تخت   
âyene-ye taxt (#)

Fr.: miroir plan   

A mirror whose reflective surface is neither concave nor convex.

plane; → mirror.

plane of polarization
  هامن ِ قطبش   
hâmon-e qotbeš

Fr.: plan de polarisation   

In a → linearly polarized light, a plane perpendicular to the → plane of vibration and containing the direction of propagation of light. It is also the plane containing the direction of propagation and the magnetic vector (H) of the electromagnetic light wave.

plane; → polarization.

plane of rotation
  هامن ِ چرخش   
hâmon-e carxeš

Fr.: plan de rotation   

For a rotating object, the plane → perpendicular to the → rotation axis.

plane; → rotation.

plane of the sky
  هامن ِ آسمان   
hâmon-e âsmân

Fr.: plan du ciel   

An imaginary plane that is perpendicular to the → line of sight.

plane; → sky.

plane of vibration
  هامن ِ شیوش   
hâmon-e šiveš

Fr.: plan de vibration   

In a → linearly polarized light, a plane perpendicular to the → plane of polarization and containing the direction of propagation of light. It is also the plane containing the direction of propagation and the electric vector (E) of the electromagnetic light wave.

plane; → polarization.

plane polarization
  قطبش ِ هامنی   
qotbeš-e hâmoni

Fr.: polarisation plane   

Same as → linear polarization.

plane; → polarization.

plane polarized light
  نور ِ قطبیده‌ی ِ هامنی   
nur-e qotbide-ye hâmoni

Fr.: lumière polarisée plane   

Light exhibiting → plane polarization. Same as → linearly polarized light.

plane; → polarized; → light.

plane wave
  موج ِ تخت   
mowj-e taxt (#)

Fr.: onde plane   

A wave whose wavefronts of constant phase are infinite parallel planes normal to the direction of propagation.

plane; → wave.

plane-parallel atmosphere
  هواسپهر ِ پراسو-تخت، جو ِ ~   
havâsepehr-e parâsu-taxthâ, javv-e ~

Fr.: atmosphère plan-parallèle   

An approximation used in many stellar atmosphere models that depict the atmosphere as being only one-dimensional and bounded at the top and bottom by horizontal plane surfaces normal to the direction of gravity.

plane; → parallel; → atmosphere.

plane-parallel plate
  تیغه‌ی ِ تخت-پراسو   
tiqe-ye taxt-parâsu

Fr.: lame plan-parallèle   

A piece of glass with plane parallel surfaces used to admit light into an optical system and to exclude dirt and moisture.

plane; → parallel; → plate.


Fr.: planemo   

An object with a mass greater than an → asteroid, but smaller than that of a → brown dwarf.

Short for planetary mass object; → planetary; → mass; → object.

sayyâré (#)

Fr.: planète   

1) A celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit. → dwarf planet.
2) → extrasolar planet.

From O.E., from O.Fr. planete (Fr. planète), from L.L. planeta (plural form planetae), from Gk. planetes (single form) "wandering," from (asteres) planetai "wandering (stars)," from planasthai "to wander," of unknown origin.

Sayyâré, from Ar. saiyârat "walker, traveller."

Planet Nine
  سیاره‌ی ِ نه   
sayyâre-ye noh

Fr.: Planète Neuf   

A hypothetical large planet in the far outer → solar system the gravitational effects of which would explain the unexpected orbital configuration of a group of → trans-Neptunian objects (TNOs). Trujillo & Sheppard (2014) noticed a clustering of the → argument of perihelion of bodies lying beyond ~150 → astronomical unit (AU), and attributed this to a hypothetical super-Earth body lying at several hundred AUs. Batygin & Brown (2016) showed numerically and analytically how the apsidal and nodal clustering of the distant TNOs arises as a result of resonant and secular dynamical effects from a distant perturber. They identified a range of semimajor axes (400-1500 AU) and eccentricities (0.5-0.8) for which a distant planet can explain the → orbital elements of the distant TNOs. The predicted planet would have a mass of 10 Earths (approximately 5,000 times the mass of → Pluto), a diameter of four times Earth and a highly elliptical orbit with an → orbital period of approximately 15,000 years.

planet; → nine.

  ۱) آسمان‌نما؛ ۲) آسمان‌خانه   
1) âsmânnemâ; 2) âsmânxâné (#)

Fr.: planétarium   

1) A device that produces a representation of the heavens by the use of a number of moving projectors.
2) The building or room in which such a device is housed.

From → planet + -arium "a place for."

&ACIRC;smânnemâ, literally "sky displayer," from âsmân "sky" (Mid.Pers. âsmân "sky, heaven;" O.Pers. asman- "heaven;" Av. asman- "stone, sling-stone; heaven;" cf. Skt. áśman- "stone, rock, thunderbolt;" Gk. akmon "heaven, meteor, anvil;" Akmon was the father of Ouranos (Uranus), god of sky; Lith. akmuo "stone;" Rus. kamen; PIE base *akmon- "stone, sky." The link between the "stone" and "sky" concepts indicates that the sky had once been conceived as a stone vault by prehistoric Indo-Europeans) + nemâ "displayer," from nemudan "to show" (Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into" (Skt. ni "down," nitaram "downward," Gk. neiothen "from below," cf. E. nether, O.E. niþera, neoþera "down, downward, below, beneath," from P.Gmc. *nitheraz, Du. neder, Ger. nieder; PIE *ni- "down, below") + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure").
&ACIRC;smânxâné, literally "sky house," from âsmân + xâné "house" (Mid.Pers. xânak, xân, xôn; cf. L. cunae "cradle;" Gk. kome "village;" Pers. Aftari dialect kiye "house, home;" PIE base *kei- "bed; to lie, to settle; beloved" (other cognates: P.Gmc. *khaim-; O.E. ham "dwelling, house, village;" E. home; Ger. Heim; L. civis "townsman;" Fr. cité; E. city; Skt. śiva- "auspicious, dear").

sayyâre-yi (#)

Fr.: planétaire   

Of, pertaining to, or resembling a planet or planets.

planet; → -ary.

planetary aberration
  بیراهش ِ سیاره‌ای   
birâheš-e sayyâreyi

Fr.: aberration planétaire   

The difference between the true position of a planet and its apparent position, due to the time required for light to travel the distance from the planet to Earth. Correction for planetary aberration is necessary in determining orbits.

planetary; → aberration.

planetary nebula
  میغ ِ سیاره‌ای   
miq-e sayyâreyi

Fr.: nébuleuse planétaire   

A hot envelope of gas ejected from a central evolved star before becoming a → white dwarf. At the end of the → asymptotic giant phase the pulsating → red giant star is surrounded by an extended shell formed by the material ejected from it. As the evolved star contracts, its → effective temperature rises considerably. When it reaches about 30,000 K, the radiated photons become energetic enough to ionize the atoms in the nebula. The nebula becomes then visible in the optical. It shines essentially in a few → emission lines, produced by cascades during recombination or by collisional excitation with electrons. The central stars of planetary nebulae, → CSPNe, are typically 0.6 to 0.8 solar masses. They have → main sequence masses in the range 1 to 8 solar masses, with an average mass of 2.2 solar masses for a standard → initial mass function. Thus a total of about 1.6 solar masses is in average lost during the → AGB and planetary nebula phases. The life-time of planetary nebulae is relatively short. A typical planetary nebula lasts only a few 10,000 years.

planetary; → nebula. The name comes from the fact that these objects appear as planetary disks in a low-resolution telescope. The first planetary nebula, designated NGC 7009 or the → Saturn Nebula, was discovered in 1782 by the German-born English astronomer William Herschel (1738-1822), who described it as "planetary nebula."

planetary physics
  فیزیک ِ سیارگان   
fizik-e sayyâregân (#)

Fr.: physique des planètes   

The study of the structure, composition, as well as physical and chemical properties of the planets of the solar system, including their atmospheres and their immediate cosmic environment.

planetary; → physics.

planetary precession
  پیشایان ِ سیاره‌ای   
pišâyân-e sayyâre-yi

Fr.: précession planétaire   

The motion of the → ecliptic plane caused by the gravitational influence of the other planets, mainly → Jupiter. The observational effect of planetary precession is similar to that of the → lunisolar precession. But planetary precession causes the → equinoxes to move along the ecliptic in the opposition direction (eastward) from that of luni-solar precession (westward) and at a much slower rate: 0''.12 per year. Same as → precession of ecliptic.

planetary; → precession.

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