Explanation:
The orbit of a body around another in space, is described by six orbital elements that determine its orientation, position, size and shape.
In the specific case of the shape of the orbit, this is determined by its eccentricity, which varies between 0 and 1 in the case of closed orbits (circle and ellipse). When the eccentricity is 0, the shape of the orbit is circular, when this value begins to vary until approaching 1 (without reaching 1), the shape of the orbit becomes more elliptical.
In this sense, a circular orbit will have an eccentriciy of zero.
