Melvin Gooden, age 11, of Shreveport, Louisiana, for his question:

What is the purpose of a planet's moons?

A space traveler leaves behind the north south, east west directions based on this planet, plus mate other earthbound ideas. Here we tend to seek the cases behind everyday events, usually so that we can control them to our liking. We feel most secure when we know the useful purpose for this and that: Out there in space, we behold the cosmic universe somewhat as strangers.

Hence, it is natural to ask the purpose of moons, planets and such, though such questions are not necessary. We may probe to learn how planets and moons were formed and perhaps even speculate about their final destinies. But the purpose of it all is beyond our imaginations  just as it is beyond our capabilities to grasp the scope of the infinite universe. We cannot explain the purpose of a planet's moons, no matter how much we learn about them.