Apsis

[æpsis]

解释:

(n.) One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line joining them, the line of apsides.

(n.) In a curve referred to polar coordinates, any point for which the radius vector is a maximum or minimum.

(n.) Same as Apse.

编辑:利瓦伊

解释:

n. one of the two extreme points in the orbit of a planet one at the greatest the other at the least distance from the sun: one of the two points in the orbit of a satellite—one nearest to the other farthest from its primary; corresponding in the case of the moon to the perigee and apogee:—pl. Apsides (ap′si-dēz).—adj. Ap′sidal.

整理:凯瑟琳