» In architecture, apsis is a synonym for apse. "Apogee," "perigee," and "aphelion" redirect here. For other uses of "apogee," see Apogee (disambiguation). For Edenbridge's album, see Aphelion (album). For the literary journal Perigee, see . In celestial mechanics, an apsis, plural apsides is the point of greatest or least distance of the elliptical orbit of an object from its center of attraction, which is generally the center of mass of the system. The point of closest approach (the point at… (More on Aphelion)