Fr.: anomalie eccentrique
Of a planetary orbit, the angle measured from the perihelion position, to the center of the circumscribing auxiliary circle, to the projected position of the planet on the circle. → anomaly; → mean anomaly; → true anomaly.
The amount by which the orbit deviates from circularity: e = c/a, where c is the distance from the center to a focus and a the semi-major axis. If e = 0, the orbit is a circle. If e < 1, the orbit is an ellipse, if e > 1 it is a hyperbola, and if e = 1 it is a parabola. The eccentricity is one of the six → orbital elements that define a → Keplerian orbit.