There's an old saying I often like to think about, "If you shoot for the moon and miss, at least you're still among the stars."
This is a good philosophy for parenting. If your child shows an interest in something, explore that topic with him or her. Even if it seems above their head and comprehension. Children pay attention. They appreciate learning. To them it's fun. And you never know where it will lead. So why not aim high?
On that note, most little children are interested in the moon, so being World Space Week starts today, make today the day you talk with your tots about the moon!
HomeboyAstronomy.com has a good guide for talking with your young children about the basics of the moon. (They also have a guide for teaching older children about astronomy).
Among HomeboyAstronomy.com's ideas:
If you have an observatory or space center nearby, take your children. I took my toddler last month to the Lowell Observatory and she was very interested in the huge telescopes and the hands on experiments. Plus, we went home with some glow in the dark moon and stars for her room.
If you can't go anywhere, you can always just look through the moon photos NASA has on their website HERE and use those in your discussion.