eccentricity
131Orbital state vectors — In astrodynamics or celestial dynamics orbital state vectors (sometimes state vectors) are vectors of position ( ) and velocity ( ) that together with their time (epoch) ( ) uniquely determine the state of an orbiting body. State vectors are… …
132Apse line — In astrodynamics apse line (or line of apsides) is a common name for an imaginary line defined by orbit s eccentricity vector. It is strictly defined for elliptic, parabolic, and hyperbolic orbits. For those orbits it can be imagined as a line:… …
