the picture at the right shows the orbits of neptune's irregular moons discovered so far. the eccentricity of the orbits is represented by the yellow segments (extending from the pericentre to the apocentre) with the inclination represented on y axis. the satellites above the x axis are prograde, the satellites beneath are retrograde. the x axis is labelled in gm (million km) and the fraction of the hill sphere's (gravitational influence) radius (~116 gm for neptune).