Examples of four orbital trajectories with different eccentricities
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:
Here is a formula to find eccentricity:
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. The near and far points are the apsides.
Images for kids
Elliptic orbit by eccentricity 0.0 · 0.2 · 0.4 · 0.6 · 0.8
Plot of the changing orbital eccentricity of Mercury, Venus, Earth, and Mars over the next 50000 years. The arrows indicate the different scales used, as the eccentricities of Mercury and Mars are much greater than those of Venus and Earth. The 0 point on this plot is the year 2007.
In Spanish: Excentricidad orbital para niños