Work out ellipse eccentricity instantly with clear inputs, formula shown and shareable results.
Eccentricity measures how far an ellipse departs from a circle: e = c/a with c = √(a² − b²). e = 0 is a circle and e → 1 is an infinitely stretched ellipse.
Eccentricity
e = √(a² − b²) / a = c / a
Semi-latus rectum
ℓ = b² / a
About 0.0167, which is why the orbit looks almost circular.
The two axes are swapped automatically so that a is always the semi-major axis.