An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 43 Search : pole
magnetic south pole
  قطب ِ دشتر ِ مغناتیسی   
qotab-e daštar-e meqnâtisi

Fr.: pôle sud magnétique   

The → counterpart of the → magnetic north pole. It lies near the → geographic north pole.

magnetic; → south; → pole.

magnetic-dipole radiation
  تابش ِ دوقطبه‌ی ِ مغناتیسی   
tâbeš-e doqotbe-ye meqnâtisi (#)

Fr.: rayonnement du dipôle magnétique   

Radiation emitted by a rotating magnet.

magnetic; → dipole; → radiation.

mean pole
  قطب ِ میانگین   
qotb-e miyângin

Fr.: pôle moyen   

The direction of the Earth's axis at a particular epoch if the nutation is ignored.

mean; → pole.


Fr.: multipôle   

An entity consisting of several poles.

multi-; → pole.

multipole index
  دیشن ِ بس‌قطبه   
dišan-e basqotbé

Fr.: indice multipolaire   

A variable used in → spherical harmonic expansions. Each spherical harmonic is characterized by its multipole index l: l = 0 for a → monopole, l = 1 for a → dipole, and so on. It is used in particular to describe the → cosmic microwave background anisotropy: ΔT/T0 (θ,φ) = Σ almYlm(θ,φ), where θ and φ are the → spherical polar coordinates, Ylm is the → spherical harmonic functions, and the sum runs over l = 1, 2, ..., ∞ and m = -l, ..., l, where the multipole index l corresponds to angular scales ≅ 180°/l.

multipole; → index.

multipole moment
  گشتاور ِ بس‌قطبه   
gaštâvar-e basqotbé

Fr.: moment multipolaire   

The quantity that gives the electric potential field due to a distribution of charges, such as a → dipole, → quadrupole, → octupole, etc. A multipole moment usually involves powers of the distance to the origin, as well as some angular dependence.

multi-; → pole; → moment.

north celestial pole
  قطب ِ آسمانی ِ هودر   
qotb-e âsmâni-ye hudar

Fr.: pôle nord céleste   

The point in the → northern hemisphere where the → rotation axis of Earth touches the → celestial sphere. The star → Polaris, also called the Pole Star, is located very near this point, at an angular separation of 42 degrees (about 1.4 lunar diameters).

north; → celestial; → pole.

north pole
  قطب ِ هودر   
qotb-e hudar

Fr.: pôle nord   

1) An → imaginary → point in the → northern hemisphere representing the intersection of the → Earth's → rotation axis with the → globe or with the → celestial sphere.
2) For a → magnet, the pole which points toward the geographic north.
3) In a → magnetic field, the point from where a → line of force is leaves for the → south pole.

north; → pole.

North Pole Star
  ستاره‌ی ِ قطب ِ هودر   
setâre-ye qotb-e hudar

Fr.: étoile du pole Nord   

A star that lies on the → rotation axis of the Earth in the north hemisphere. The → Pole Star is not, in the long term, permanently fixed to the → celestial pole. This is because of the Earth's → axial precession which gradually moves the celestial poles in the sky. It takes about 26,000 years for the precession to turn the pole a full circuit. Currently the North Pole Star is → Polaris, which will continue to mark the north celestial pole for several more centuries. But, around 4,000 B.C. → Gamma Cephei will become the North Pole Star. Around 7,500 B.C., → Alderamin will take up the role. And it will be the brilliant → Vega's (Alpha Lyrae) turn in about 12,000 years. In the past, about 3,000 B.C., → Thuban (Alpha Draconis) was the North Pole Star. Then → Kokab (Beta Ursae Majoris) became the Pole Star from 1500 B.C. to 500 A.D. before leaving the task to Polaris.

north; → pole; → star.


Fr.: octupôle   

A → multipole consisting of eight point charges. Octupole moments are much smaller than → quadrupole moments and very much smaller than → dipole moment.

oct-; → pole.

qotb (#)

Fr.: pôle   

1) Either extremity of the axis of the Earth or of any spherical body.
2) Either of the two regions or parts of an electric battery, magnet, or the like, at which the magnetic flux density is concentrated.
3) → pole of a mirror.
4) The fixed point in a system of polar coordinates that serves as the origin.

M.E., from L. polus "end of an axis, the sky," from Gk. polos "pivot, pole," polein "move around;" from PIE base *kwel- "to turn, move around, sojourn, dwell;" cognate with Pers. carx "every thing performing a circulatory motion; a wheel; a cart;" Av. caxra- "wheel," caraiti "he moves, approaches;" cf. Skt. cakra- "wheel, circle; cycle," carati "he moves, wanders;" Gk. kyklos "circle, wheel" (loaned L.L. cyclus); L. colere "to dwell in, to cultivate, move around," colonus "farmer, settler;" O.E. hweol "wheel;" Rus. koleso "wheel."

Qotb, from Ar. quTb.

pole of a mirror
  قطب ِ آینه   
qotab-e âyene

Fr.: pôle de mirroir   

The point where the → principal axis passes through the mirror.

pole; → mirror.

pole star
  ستاره‌ی ِ قطبی   
setâre-ye qotbi (#)

Fr.: étoile polaire   

A star that lies along the Earth's → rotation axis. The term usually refers to the star → Polaris, which is the current → North Celestial Pole star. The → South Celestial Pole is not currently associated with any bright star. See also: → North Pole Star, → South Pole Star.

pole; → star.

cahârqotbé (#)

Fr.: quadrupôle   

A set of either two → electric dipoles or two → magnetic dipoles in close proximity to each other arranged with alternating polarities and acting as a single unit. Quadrupole interactions are much smaller than dipole interactions, but can allow transitions forbidden in dipole moment transitions.

From L. quadru-, variant of quadri- "four" + → pole, on the model of → dipole.

Cahâr, → four, + qotb, → pole + noun/nuance suffix .

quadrupole anisotropy
  نا-ایزوگردی ِ چهارقطبه   
nâ-izogardi-ye cahârqotbé

Fr.: anisotropie quadrupolaire   

The → anisotropy which is at the origin of the → cosmic microwave background polarization. The quadrupole anisotropy could arise from three types of perturbations: → scalar perturbation, → vector perturbation, and → tensor perturbation

quadrupole; → anisotropy.

quadrupole lens
  عدسی ِ چهارقطبه   
adasi-ye cahârqotbé

Fr.: lentille quadrupôle   

A device, consisting of four → electrodes or → magnetic poles arranged in alternating → polarity, that focuses a beam of → charged particles.

quadrupole; → lens.

quadrupole moment
  گشتاور ِ چهارقطبه   
gaštâvar-e cahârqotbé

Fr.: moment quadrupolaire   

A quantity characterizing an electric charge distribution, determined by the product of the charge density, the second power of the distance from the origin, and a spherical harmonic over the charge distribution.

quadrupole; → moment.

south celestial pole
  قطب ِ آسمانی ِ دشتر   
qotb-e âsmâni-ye daštar

Fr.: pôle sud céleste   

The point in the → southern hemisphere where the → rotation axis of the Earth touches the → celestial sphere. In contrast to the → north celestial pole, no bright star is visible in that direction.

north; → celestial; → pole.

south pole
  قطب ِ دشتر   
qotb-e daštar

Fr.: pôle Sud   

1) An → imaginary point in the → southern hemisphere representing the intersection of the → Earth's → rotation axis with the → globe with the → celestial sphere.
2) For a → magnet, the pole which points toward the geographic south.
3) In a → magnetic field, the point which receives a → line of force coming from the → north pole.

south; → pole.

South Pole Star
  ستاره‌ی ِ قطب ِ دشتر   
setâre-ye qotb-e daštar

Fr.: étoile du pôle sud   

A star that would mark the south → celestial pole. Presently no bright visible star is situated along the → rotation axis of the Earth in the southern hemisphere. But, because of the Earth's → axial precession, about 7,000 years from now the star → Delta Velorum in the constellation → Vela, the Sail, will come to within 0.2 degrees of the South Celestial Pole (around the year 9250 B.C.). That is closer to marking the celestial pole than → Polaris or → Sirius ever do during their reigns as pole stars! Sirius will become the South Pole Star some 60 thousand years from now (around the year 66270 B.C.). In that time, Sirius will come to within 1.6 degrees of the South Celestial Pole.

south; → celestial; → pole.

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