"Planetary orbits" refers to the circular or elliptical paths that planets take when they move around the Sun. It shows how planets travel in a loop around the Sun due to gravity, just like how the Moon goes around the Earth. Full definition
Each section of the novel is named for a stage of planetary orbit. (bookbrowse.com)
reduces the likelihood of stable planetary orbits at increasing distances from each star or binary pair Alan Hale, 1994. (solstation.com)
Finally, noncoplanarity between the component stars of a binary system should not have a significant impact on the stability of close - in planetary orbits around each star (Alan Hale, 1994). (members.nova.org)