An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < abe Lis orb > >>

Number of Results: 60 Search : orbit
Lissajous orbit
  مدار ِ لیساژو   
madâr-e Lissajous

Fr.: orbite de Lissajous   

A quasi-periodic path resembling a → Lissajous figure around the L1 or L2 → Lagrangian points of a two-body system. Lissajous orbits, resulting from a combination of planar and vertical components, are used by certain space telescopes (such as → WMAP, → Planck Satellite, and → Herschel Satellite) that are required to be in a stable position relative to the Earth and Sun while making long-term observations.

Lissajous figure; → orbit.

lunar orbit node
  گره ِ مداری ِ ماه   
gereh-e madâri-ye mâh

Fr.: nœud de l'orbite lunaire   

Same as → lunar node.

lunar; → orbit; → node.

lunar sidereal orbital period
  دوره‌ی ِ مداری ِ اختری ِ مانگ   
dowre-ye madâri-ye axtari-ye mâng

Fr.: période orbitale sidérale de la Lune   

Same as → sidereal month.

lunar; → sidereal; → orbital; → period.

minimum orbit intersection distance (MOID)
  دورای کمینه‌ی ِ اندرسکنج ِ مدار   
durâ-ye kamine-ye andarsekanj-e madâr

Fr.: distance minimale d'intersection d'une orbite   

The minimum distance between the paths of two orbiting objects around a → primary. Such distance between an object and Earth is called Earth MOID.

minimum; → orbit; → intersection; → distance.

orbit
  مدار   
madâr (#)

Fr.: orbite   

The path followed by a body moving in a gravitational field. For bodies moving under the influence of a centrally directed force, without significant perturbation, the shape of the orbit must be one of the conic section family of curves (circle, ellipse, parabola, or hyperbola).

L. orbita "wheel track, course, circuit."

Madâr, from Ar.

orbit decay
  تباهیِ مدار   
tabâhi-ye madâr

Fr.: déclin d'orbite   

A gradual change in the orbit of a spacecraft caused by aerodynamic drag of a planet's outer atmosphere and other forces.

orbit; → decay.

orbital
  ۱) مداری؛ ۲) مدارال   
1) madâri; 2) madârâl

Fr.: 1) orbital; 2) orbitale   

1) Of or relating to an orbit.
2) A wave function that describes the state of an electron with a given energy (n, l, and ml quantum numbers) in an atom (atomic orbital) or in a molecule (molecular orbital).

Orbital, from → orbit + → -al.

orbital angular momentum
  جنباک ِ زاویه‌ای ِ مداری   
jonbâk-e zâviyeyi-ye madâri

Fr.: moment cinétique orbital, ~ angulaire ~   

1) Mechanics: The → angular momentum associated with the motion of a particle about an origin, equal to the cross product of the position vector (r) with the linear momentum (p = mv): L = r x p. Although r and p are constantly changing direction, L is a constant in the absence of any external force on the system. Also known as orbital momentum.
2) Quantum mechanics: The → angular momentum operator associated with the motion of a particle about an origin, equal to the cross product of the position vector with the linear momentum, as opposed to the → spin angular momentum. In quantum mechanics the orbital angular momentum is quantized. Its magnitude is confined to discrete values given by the expression: ħ &radic l(l + 1), where l is the orbital angular momentum quantum number, or azimuthal quantum number, and is limited to positive integral values (l = 0, 1, 2, ...). Moreover, the orientation of the direction of rotation is quantized, as determined by the → magnetic quantum number. Since the electron carries an electric charge, the circulation of electron constitutes a current loop which generates a magnetic moment associated to the orbital angular momentum.

orbital; → angular; → momentum.

orbital axis
  آسه‌ی ِ مداری   
âse-ye madâri

Fr.: axe orbital   

The → perpendicular to the → orbital plane.

orbital; → axis.

orbital debris
  تیفالِ مداری   
tifâl-e madâri

Fr.: débris spatial   

Objects in orbit around Earth created by humans, that no longer serve any useful purpose. They consist of everything from entire spent rocket stages and defunct satellites to explosion fragments, paint flakes, dust, and slag from solid rocket motors, and other small particles. Also called space junk and space waste.

orbital; → debris .

orbital electron
  الکترونِ مداری   
elektron-e madâri (#)

Fr.: électron orbital   

An electron contained within an atom which may be thought of as orbiting around the nucleus, in a manner analogous to the orbit of a planet around the Sun.

orbital; → electron .

orbital element
  بُن‌پارِ مداری   
bonpâr-e madâri

Fr.: élément orbital   

Any of the six parameters needed to specify the → orbit of an object around a → primary body (such as a planet around the Sun or a satellite around the Earth) and give its position at any instant. Two of them define the size and the form of the orbit: → semi-major axis (a) and → eccentricity (e). Three angular values determine the orbit position in space: the → inclination (i) of the object's → orbital plane to the reference plane (such as the → ecliptic), the → longitude of ascending node (Ω), and the → argument of periapsis (ω). And finally the sixth element is the → time of periapsis passage which allows calculating the body's position along the orbit at any instant.

orbital; → element.

orbital energy
  کاروژِ مداری   
kâruž-e madâri

Fr.: énergie orbitale   

The → sum of the → potential energy and the → kinetic energy of an object in → orbit.

orbital; → energy.

orbital inclination
  درکیلِ مداری   
darkil-e madâri

Fr.: inclinaison orbitale   

An → orbital element that defines the angle between the orbital plane of a solar system body (planet, comet, asteroid) and the plane of the ecliptic. The orbital inclination of the Earth's orbit is 0°; those of Mercury, Venus, and Mars are 7.01°, 3.39°, and 1.85° respectively.

orbital; → inclination .

orbital maneuver
  مانوور ِ مداری   
mânovr-e madâri

Fr.: mainoeuvre orbitale   

The moving of a spacecraft between two different orbits resulting from a change in its velocity (acceleration). Generally, manoeuvres are caused by → thrust from the spacecraft's motors.

orbital; → maneuver.

orbital manoeuvre
  مانوور ِ مداری   
mânovr-e madâri

Fr.: mainoeuvre orbitale   

orbital maneuver.

orbital; → manoeuvre.

orbital migration
  کوچِ مداری   
kuc-e madâri

Fr.: migration orbitale   

Theoretical prediction according to which a → giant planet, formed in the outer regions of a → protoplanetary disk, could migrate inward by losing → energy and → angular momentum as the result of → gravitational interactions with the remnants of the disk. This orbital migration could explain the presence of giant gaseous Jupiter-like planets (→ hot Jupiters) very close to their host stars.

orbital; → migration.

orbital node
  گره ِ مداری   
gereh-e madâri

Fr.: nœud orbital   

One of the two points of intersection of the orbit of a secondary body with the plane of reference through the primary.

orbital; → node.

orbital parameter
  پارامون ِ مداری   
pârâmun-e madâri

Fr.: paramètre orbital   

orbital element.

orbital; → parameter.

orbital period
  دوره‌یِ مداری   
dowre-ye medâri (#)

Fr.: période orbitale   

The time interval between two successive passages of an object through the same point in its orbit around another object.

orbital; → period .

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