The space between the objects in the solar system.

the part of outer space within the solar system

The space between planets.

Regions among the planets, moons, and related objects of the Solar System.

Interplanetary space is that part of outer space between planets in a solar system and its local star(s), many of which are binaries. Around any one planet, "interplanetary" space begins in the broad region where any amosphere, magnetic field and moons end, ceding dominance to the local star; in our case, the Sun. The diffuse outer boundary of our interplanetary space is characterized by the heliopause, where the solar wind meets the interstellar medium, and by the Oort cloud, the region where comets originate.