High Quality Content by WIKIPEDIA articles! A circumbinary planet is a planet that orbits two stars instead of one. Because of the close proximity and orbit of some binary stars, the only way for planets to form is by forming outside the orbit of the two stars. Currently there are only five confirmed systems of circumbinary planets: PSR B1620-26, HW Virginis, Kepler-16, DP Leonis, and NN Serpentis.