mean daily motion
jenbeš-e ruzâne-ye miyângin (#)
Fr.: mouvement diurne moyen
The average movement of a body along its orbit in one day, usually expressed in degrees.
Fr.: élément moyen
An element of an adopted reference orbit that approximates the actual, perturbed orbit. Mean elements may serve as the basis for calculating perturbations.
Fr.: équateur moyen
The orientation the Earth's equator would have if the nutation was subtracted.
Fr.: équinoxe moyen
A fictitious equinox whose position is that of the vernal equinox at a particular epoch with the effect of nutation removed.
mean free path
puyeš-e âzâd-e miyângin (#)
Fr.: libre parcours moyen
The mean distance which a particle moves between two successive collisions with other particles of the medium. Mean free path is inversely proportional to the number of particles per cm3 (n), and the collision → cross section (σ). In the case of a gas with molecules having a diameter of d, the cross section is equal to the area of a circle of radius d, i.e. σ = πd2, and the mean free path is given by: l = 1/(nσ). Taking into account the relative velocity distribution of the colliding molecules, l = 1/(√2 . nσ). For a gas at one atmosphere pressure and room temperature, the average distance between molecules is roughly 3.5 × 10-7 cm, that is some 35 times the diameter of a molecule. Taking the gas density n = 2.4 × 1014 molecules cm-3, and a typical diameter d = 2 × 10-8 cm for a molecule, the mean free path is 3.3 × 10-5 cm. This means that the average distance between collisions is about 95 times the average distance between molecules.
Fr.: vie moyenne
The average amount of time an unstable radioisotope exists before it decays, It is equal to 1.44 times the half-life.
mean molecular weight
vazn-e molekuli-ye miyângin (#)
Fr.: poids moléculaire moyen
The total atomic or molecular weight divided by the total number of particles. For instance, the mean molecular weight of a plasma of pure ionized 4He would be 4 (the atomic mass number) divided by 3, the total number of particles (1 nucleus plus 2 electrons), i.e. 4/3.
mâh-e miyângin (#)
Fr.: lune moyenne
A fictitious Moon that has the same average motion as the true Moon but that is not subject to any gravitational perturbations by other bodies.
jonbeš-e miyângin (#)
Fr.: mouvement moyen
The average angular velocity of a satellite in an elliptical orbit.
Fr.: parallaxe moyenne
The parallax, derived by means of statistical studies of brightness and motions, for a large group of stars whose individual parallaxes cannot be measured.
Fr.: position moyenne
An object's celestial position as determined for a given mean equator and equinox. → mean position.
Fr.: pôle moyen
The direction of the Earth's axis at a particular epoch if the nutation is ignored.
Fr.: position moyenne
Same as → mean place.
Fr.: profil moyen
The shape of a pulsar's pulse as determined by averaging several pulses.
mean sidereal day
ruz-e axtari-ye miyângin
Fr.: jour sidéral moyen
mean sidereal time
zamân-e axtari-ye miyângin (#)
Fr.: temps sidéral moyen
The hour angle of the mean equinox for a given observer.
mean solar day
ruz-e xoršidi-ye miyângin (#)
Fr.: jour solaire moyen
The average length of the apparent solar day. In other words, the interval between successive transits of the mean Sun for a given observer.
mean solar time
zamân-e xoršidi-ye miyângin (#)
Fr.: temps solaire moyen
The time since the mean Sun crossed the meridian with 12 hours added to make the day begin at midnight.
Fr.: spectre moyen
A plot of the mass-to-charge ratio of elementary particles, sorted by their isotopic mass.
xoršid-e miyângin (#)
Fr.: Soleil moyen
A hypothetical Sun that moves along the ecliptic at a uniform rate equal to the average motion of the real Sun.