Orbital eccentricity
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In astrodynamics, orbital eccentricity shows how much the shape of an object's orbit is different from a circle.
Eccentricity (
) is defined for all circular, elliptic, parabolic and hyperbolic orbits. It can take the following values:
- for circular orbits:
is equal to zero, - for elliptic orbits:
is more than zero but less than 1, - for parabolic trajectories:
is equal to 1, - for hyperbolic trajectories:
is more than 1.
Finding eccentricity [change]
Use this formula:
, where eobj is the eccentricity, ra is the apoapsis (far point) of the object's orbit, and rp is the periapsis (near point) of the object's orbit.