Celestial Navigation is not hard to learn. There are programs for fifth graders to learn celestial positioning as an Earth Science project. However, the degree to which one wishes to become proficient does dictate a variation in depth of material trewatment. This catalog contains books that will teach the taking a simple sextant sight, all the way to writing your own computer program, or even telling the time from the moon. The fun of celestial navigation lies in the fact that it is a challenge, and that you can take it as far as you want.