You searched for: “ellipticity
ellipticity
The variation of a regular planar or solid shape from a perfect circle or sphere.

The departure of the earth, which has a smaller polar than equatorial diameter, from a perfect sphere is more usually described as its oblateness.

Elliptical planetary orbits are more usually described in terms of their eccentricity.

This entry is located in the following unit: Astronomy and related astronomical terms (page 9)