Apsis - Perihelion Information

Apsis - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Apsis
An apsis (Greek ἁψίς, gen. ἁψίδος), plural apsides (pron.: /ˈæpsɨdiːz/; Greek: ἁψίδες), is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usuall