Like you or me, a planet has a purpose, just as each element belonging to a system fulfills a function within the system. This planet, where we inhabit and live, houses or contains life, and there are millions of millions of planets in the universe, on the other hand, life "apparently" is not common in the universe, but planets are, as well as stars. Therefore, it can be inferred that a planet has the purpose of harboring life and the stars provide adequate heat to maintain life.