| 释义 |
apse (apsis) A point in an orbit at which the body is moving in a direction perpendicular to its position vector. In an elliptical orbit in which the centre of attraction is at one focus there are two apses, the points at which the body is at its nearest and its farthest from the centre of attraction. When the centre of attraction is the Sun, the points at which the body is nearest and farthest are the perihelion and the aphelion. When the centre of attraction is the Earth, they are the perigee and the apogee.
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