Planetrange

Planetrange is a term used in planetary science and, occasionally, in science fiction to denote the range of orbital distances around a star within which planets can maintain long-term dynamical stability in a given planetary system. The concept serves as a shorthand for how gravitational interactions, resonances, and past migration shape the arrangement of planets. The exact boundaries of a planetrange depend on factors such as stellar mass, planetary masses, orbital eccentricities, and the presence of additional bodies; researchers estimate it with numerical simulations and analytic criteria related to orbital stability.

In practice, a planetrange is described by an inner edge and an outer edge. The inner edge often arises from strong resonant interactions or tidal effects that clear or destabilize nearby orbits, while the outer edge can be set by gravitational perturbations from distant companions, disk dispersal histories, or secular perturbations. The planetrange may overlap with other region definitions, such as the habitable zone, but it is defined primarily by dynamical stability rather than by stellar flux or climate criteria.

Applications of the concept include interpreting observed planetary system architectures, guiding searches for additional planets in known systems, and discussing the likelihood of undiscovered planets within certain orbital spans. The term is not universally standardized and can be used with varying precision across studies, sometimes equated to the region of long-term stability or to a more restricted, configuration-dependent range.