Ellipsicity

Ellipsicity is a term used in various scientific fields to describe the degree to which something is elliptical, deviating from a perfect circle or a straight line. In mathematics and geometry, it quantifies the deviation of an ellipse from a circle. A perfect circle has an ellipsicity of zero, while increasingly elongated ellipses have higher values.

In astronomy, ellipsicity is particularly relevant when discussing orbits. Celestial bodies do not typically follow perfectly circular paths; instead, their orbits are elliptical. The degree of this ellipticity, often represented by the eccentricity parameter, determines how far the orbit deviates from a circle. A low eccentricity indicates an orbit close to circular, while a high eccentricity signifies a more elongated, "squashed" orbit. This orbital ellipsicity affects factors such as the varying distance of a planet from its star and the speed at which it travels.

The concept also appears in physics, especially in the study of wave propagation and polarization. For example, the polarization state of light can be described by its ellipsicity, which indicates whether the light wave's electric field oscillates along a straight line (linear polarization), in a circle (circular polarization), or in an ellipse (elliptical polarization). Similar concepts are applied in geophysics when describing the shape of seismic waves or the deformation of the Earth's crust. The specific definition and measurement of ellipsicity can vary depending on the context, but the underlying principle remains the quantification of deviation from a simpler, non-elliptical form.