Hill Sphere

The hill sphere of a celestial body is the region where its gravitational influence dominates above all others. A stable orbit will always reside within the hill sphere of the parent body, whether it be a spacecraft orbiting a large asteroid or a planet orbiting a star. Every body of significant mass has a hill sphere. Larger objects like stars will have dotted pockets of other hill spheres from the planets within their system, which in turn are pocketed with moon hill spheres.

Generally, the hill sphere of a planetary body extends between the L1 and L2 lagrange points of the body and its parent, which can be considered gravitational “humps” when accounting for gravitational attraction and centripetal force from orbital velocity. These L1 and L2 points are the only regions within star systems that are stable for entry and exit of subspace by warp drive spacecraft.