The point in an orbit where the moving body lies furthest from the celestial body around which it turns.
apsis (pl. apsides)
L. apsis "arch, vault," from Gk. hapsis "loop, arch," from haptein "fasten together".
Mod.Pers. habâk "top of the head; the summit of a mountain".
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