argument of periapsis
Fr.: argument du périastre
The angular distance between the → ascending node of an object orbiting a → primary and its periapsis measured from the primary. Argument of periapsis is measured in the → orbital plane in the direction of motion. It is one of the → orbital elements. See also → argument of perigee, → argument of perihelion.
The point in an orbit of a body where it is closest to its primary; opposite of → apoapsis.
time of periapsis passage
zamân-e gozar az pirâhabâk
Fr.: temps de passage au périapse