Planètes

une planète = a planet (pronunciation is pretty much the same)

And here is a trick that is taught in middle school to remember the order of planets:
Mes Vieilles Tantes Mangeaient Jadis Sur Une Nappe Percée

vieux ('x' is silent) / vieille = old
une tante = aunt
mangeaient = ate
une nappe = a table cloth
percé / percée = pierced, with holes

The first letter of each word in the sentence ("my old aunts ate on a table cloth with holes") corresponds to a planet, and when there is ambiguity the second letter clarifies it. The planets, in French, are:
Mercure Venus Terre (Earth) Mars Jupiter Saturne Uranus Neptune Pluton

Of course, how that will be impacted by the demotion of Pluto remains to be seen...