tarâmun-e zâviye-yi, qotr-e ~
Fr.: diamètre angulaire
The apparent diameter of an object in angular measure.
angular diameter distance
Fr.: distance angulaire
1) The ratio of an object's → linear size (l)
to its → angular size (δθ, in
→ radians), that is
DA = l/δθ.
It is used to convert observed angular separations into proper separations
at the source.
tarâmun-e padidâr, qotr-e ~
Fr.: diamètre apparent
The angular diameter of a celestial body expressed in degrees, minutes, and seconds of arc, or in radians.
Any chord passing through the center of a figure. The length of this chord.
O.Fr. diamètre, from L. diametrus, from Gk. diametros "diagonal of a circle," from dia- "across, through" + metron "a measure" → meter.
Tarâmun, from tarâ- "across, through," → trans- + mun/mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl," from O.Pers./Av. mā(y)- "to measure," cf. Skt. mati "measures," matra- "measure," Gk. metron "measure," L. metrum; PIE base *me- "to measure."
Fr.: diamètre linéaire
The real physical diameter, as opposed to angular diameter.
The angle at the observer subtended by the equatorial radius of the Sun, Moon, or a planet.