Eccentricity

Eccentricity describes how elliptical (i.e., oval shaped) an orbit is. Eccentricity values range from 0 to almost 1. An eccentricity of 0 describes a perfectly circular orbit. The larger the eccentricity, the more elliptical the orbit.

Examples of orbital ellipses with different eccentricities.
Examples of orbital ellipses with different eccentricities. Credit: Rubin Observatory

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