Planetary rhymes with:
interplanetary, interplanetary, interplanetary, unsanitary, dignitary, interplanetary, monetary, unsanitary, cemetery, cometary, dietary, dignitary, hereditary, interplanetary, military, monetary, nonmilitary, paramilitary, pituitary, proprietary, salutary, secretary, solitary, tributary, unsanitary
Planetary sounds like:
palmateer, palmatier, palminteri, palmiter, planter, plunder, polandri, polyandry