Lissajous orbit 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 gereh-e madâri-ye mâh Fr.: nœud de l'orbite lunaire Same as → lunar node. |
lunar sidereal orbital period dowre-ye madâri-ye axtari-ye mâng Fr.: période orbitale sidérale de la Lune Same as → sidereal month. |
minimum orbit intersection distance (MOID) 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 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 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. |
orbital 1) madâri; 2) madârâl Fr.: 1) orbital; 2) orbitale 1) Of or relating to an orbit. |
orbital angular momentum 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. |
orbital axis âse-ye madâri Fr.: axe orbital The → perpendicular to the → orbital plane. |
orbital debris 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 electron 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 element 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 energy kâruž-e madâri Fr.: énergie orbitale The → sum of the → potential energy and the → kinetic energy of an object in → orbit. |
orbital inclination 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 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 manoeuvre mânovr-e madâri Fr.: mainoeuvre orbitale |
orbital migration 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 node 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 parameter pârâmun-e madâri Fr.: paramètre orbital |
orbital period 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. |