The term 'orbit part' can be summarized by the crossword solution 'APOGEE, ' which is a six-letter word. APOGEE is the point in an orbit when an object is furthest from the Earth, or at its highest point. It is the opposite of perigee, which is the point in an orbit when an object is closest to the Earth, or at its lowest point. APOGEE and perigee are important terms in orbital mechanics, which is the study of the motion of objects in space.