In stellar dynamics a box orbit refers to a particular type of orbit which can be seen in triaxial systems, that is, systems which do not possess a symmetry around any of its axes. They contrast with the loop orbits which are observed in spherically symmetric or axisymmetric systems.
In a box orbit, the star oscillates independently along the three different axes as it moves through the system. As a result of this motion, it fills in a (roughly) box-shaped region of space. Unlike loop orbits, the stars on box orbits can come arbitrarily close to the center of the system. As a special case, if the frequencies of oscillations in different axes are exact multiples of each other, the orbit will be closed.
