An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 72 Search : angle
critical angle
  زاویه‌ی ِ پرژنی   
zâviyeh-ye paržani

Fr.: angle critique   

Angle of incidence of light proceeding from a denser medium toward a thinner, at which grazing refraction occurs (angle of refraction 90°).

critical; → angle.

deflection angle
  زاویه‌ی ِ واچفت   
zâviye-ye vâcaft

Fr.: angle de déflexion   

1) The angle by which a light ray is curved by the gravitational field of a massive body. Einstein's general relativity predicts that a light ray which tangentially grazes the surface of the Sun is deflected by 1''.7. This result was confirmed in 1919 when the apparent angular shift of stars close to the limb of the Sun was measured during a total solar eclipse.
2) In a cathode-ray tube, the angle through which the beam is bent, vertically, horizontally, or diagonally.

deflection; → angle.

dihedral angle
  زاویه‌ی ِ دودیمی   
zâviye-ye dodimi

Fr.: angle dièdre   

An angle formed by two planes meeting along a common line. Compare with → face angle.

angle; → dihedral.

dip angle
  زاویه‌ی ِ نشیب   
zâviye-ye našib

Fr.: angle d'inclinaison   

The angular difference between the → visible horizon and the → true horizon. Same as → dip of the horizon.

dip; → angle.

direction angle
  زاویه‌ی ِ راستا   
zâviye-ye râstâ

Fr.: angle de direction   

An angle made by a given vector and a coordinate axis.
The angle between the North and a chosen direction.

direct; → angle.

  هم‌گوریدن، هم‌پیچیدن   
ham-guridan, ham-picidan

Fr.: emmêler   

To wrap or twist together; to intertwine.

From → en- "in," + tangle, from M.E. tangilen, tagilen "to entangle."

Hamgureš, from ham- "together," → com-, + guridan "to become tangled, as threads or hairs, entwine," probably related to greh "knot," → node.
Hampicidan, from ham- + picidan "to twist, entwine, coil."

  هم‌گورش، هم‌پیچی   
ham-gureš, ham-pici

Fr.: emmêlment   

The act of entangling. The state of being entangled.

Verbal noun of → entangle; → -ment.

epoch angle
  زاویه‌ی ِ زیمه   
zâviye-ye zimé

Fr.: angle de phase initial   

Same as the → initial phase angle.

epoch; → angle.

equilateral triangle
  سه‌بر ِ سه-پهلو-برابر   
sebar-e sé-pahlu-barâbar (#)

Fr.: triangle équilatéral   

A triangle having three equal sides.

equi-, → lateral, → triangle.

Sé-pahlu-barâbar, from , → three, pahlu, → side, barâbar, → equal.

face angle
  زاویه‌ی ِ دیمی، دیم-زاویه   
zâviye-ye dimi, dim-zâviyé


An angle formed by any two adjacent edges of a → polyhedron, in contrast to a → dihedral angle.

face; → angle.

grating angle
  زاویه‌ی ِ توری   
zâviye-ye turi (#)

Fr.: angle de réseau   

The angle between the incident optical beam and the normal to the grating. It is the angle to which the grating must be set to place the desired wavelength at the center of the detector.

grating; → angle.

hour angle
  زاویه‌ی ِ ساعتی   
zâviye-ye sâati (#)

Fr.: angle horaire   

A telescope based coordinate specifying the angle, in the equatorial plane, from the meridian to a plane containing the celestial object and the north and south celestial poles.

hour; → angle.

incidence angle
  زاویه‌ی ِ فتاد   
zâviye-ye fotâd

Fr.: angle d'incidence   

Same as → angle of incidence.

incidence; → angle.

initial phase angle
  زاویه‌ی ِ فاز ِ آغازین   
zâviye-ye fâz-e âqâzin

Fr.: angle de phase initial   

The value of the phase corresponding to the origin of time. Same as the → epoch angle.

initial; → phase; → angle.

inscribed angle
  زاویه‌ی ِ دروِشته   
zâviye-ye davešté

Fr.: angle inscrit   

An angle whose vertex lies on a circle and whose sides are chords of the circle.

Inscribed p.p. of → inscribe; → angle.

isokinetic angle
  زاویه‌ی ِ ایزوجنبشی   
zâviye-ye izojonbeši

Fr.: angle isocinétique   

Adaptive optics: The angle over which wavefront phases become de-correlated by 1 radian rms due to → tip-tilt alone. It is defined analogously to the → isoplanatic angle.

iso-; → kinetic; → angle.

isoplanatic angle
  زاویه‌ی ِ ایزوبیراه   
zâviye-ye izobirâh

Fr.: angle isoplanatique   

The angle in which the → point spread function of the atmosphere/telescope system is space invariant. Because of the presence of → turbulence in high layers of the atmosphere, this angle is extremely small, often only a few seconds of arc at visible wavelengths. See also → aplanatism.

isoplanatic; → angle.

isosceles triangle
  سه‌بر ِ دو-پهلو-برابر   
sebar-e do-pahlu-barâbar (#)

Fr.: triangle équilatéral   

A triangle having two sides equal.

From L.L. isosceles, from Gk. isoskeles "with equal legs; that can be divided into two equal parts," from isos "equal, identical," → iso-, + skelos "leg."

Sebar, → triangle, do-pahlu-baraabar, from do, → two, pahlu, → side, barâbar, → equal.

Mach angle
  زاویه‌ی ِ ماخ   
zâviye-ye Mach

Fr.: angle de Mach   

Half of the vertex angle of the → Mach cone generated by a body in → supersonic flight. It is given by sin μ = (a/v), where a is the speed of the sound waves and v the velocity of the object. In terms of Mach number: μ = asin (1/M). The Mach angle diminishes with the object velocity. For M = 1 it is 90°, for M = 2, it is 30°, and for M = 5, its is 11.5°.

Mach number; → angle.

meridian angle
  زاویه‌ی ِ نیمروزان   
zâviye-ye nimruzân

Fr.: angle horaire   

Same as hour angle.

meridian; → angle.

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