An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Physics: The condition, in a system, of having opposite characteristics at different points, especially positive or negative with respect to electric charge or magnetic properties.
2) Chemistry: A property of a molecule caused by unsymmetrical charge distribution.

From → polar + → -ity.

The time during which the Earth's magnetic field was of a single polarity; an interval of time between reversals of Earth's magnetic field.

→ polarity; → epoch.

A specific event in the history of Earth's magnetic field. Usually used in reference to a specific → polarity reversal.

→ polarity; → event.

1) A change in the → polarity of Earth's magnetic field in which the north magnetic pole becomes the south magnetic pole and vice versa. Also known as geomagnetic reversal or magnetic reversal. Earth's magnetic field has reversed many times in the past and the time intervals between these changes are known as → polarity epochs.
2) The change in the polarity of the → solar magnetic field with the ending of each → solar activity cycle so that the North magnetic pole becomes the South and vice versa.

→ polarity; → reversal.

Able to be polarized.

→ polaize; → -able.

1) Optics: A process or state in which the directions of the electric or magnetic fields of an → electromagnetic radiation change in a regular pattern. Light can be polarized by a variety of ways, involving the following processes: reflection, transmission, double refraction, and scattering. See also → unpolarized light; → linear polarization; → circular polarization; → elliptical polarization. The study of the polarization of light from astronomical sources can yield unique information in particular related to the properties of magnetic fields.
2) Electricity: A process or state in which the → dipole moments of → polar molecules in a → dielectric material get aligned under the action of an external electric field. Actually thin layers of bound charges with opposite signs appear on the surfaces of the dielectric.
3) Electricity: The accumulation of ions, produced during electrolysis, on the electrodes of a cell, increasing the resistance of the cell.

Verbal noun of → polarize.

Same as → polarizing angle and → Brewster angle.

→ polarization; → angle.

Same as → bound charge.

→ polarization; → charge.

→ degree of polarization.

→ polarization; → degree.

The ratio expressed by P = (I_par - I_per) / (I_par + I_per), where I_par and I_per are the light intensities with the electric field vector respectively parallel and perpendicular to the incident beam.

→ polarization; → fraction.

To cause → polarization. To undergo polarization.

Infinitive of → polarization.

Of or pertaining to a medium or physical phenomenon that exhibits → polarization.

P.p. of → polarize.

→ Electromagnetic radiation in the optical region which has undergone → polarization.

Past participle of → polarize; → light.

An optical device capable of transforming natural light into polarized light, usually by selective transmission of polarized rays.

Agent noun of → polarize.

The angle of → incidence for which the reflected light is completely polarized. Also called the → Brewster angle and → polarization angle. See also → Brewster's law.

Polarizing, adj. of → polarize; → angle.

A filter that polarizes light passing through it.

Polarizing, adj. of → polarize; → filter.

A prism that is used to produce or analyze plane-polarized light.

Polarizing, adj. of → polarize; → prism.

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.

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

→ pole; → mirror.

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.