The moon has comforted man for thousands of years. It's been everything from a god to a compass, and the only cosmic body human beings have ever visited. NASA is planning to build a permanent outpost there. Discover how the moon came to be--if you don't already know, you will be astounded.

Examining Mercury and Venus. Included: exploring how the damages they've suffered from cosmic collisions and acid rain may serve as a warning for Earth.