Galilean Project One: Moon

Galilean Project One: Moon

INTRODUCTION. In this Galilean exercise, you will see how the people of Galileo's time could say that everything revolved around the earth. They'd say: "Galileo, it is obvious that the sun goes around the earth. Everyone can see that! And look at the moon, it must also go around the earth. Its phases and the eclipses show that it does. We don't know what you are talking about, Galileo. You must stop thinking your crazy thoughts!"

Support the thoughts of those discreditors by using your darkened room with a central lightbulb, and your head as earth. But this time have your friend slowly make the soccer ball orbit around you. You will see that what the ancients were saying is correct - IF you didn't know that the earth was going around the sun rather than sun around the earth.

Now let's make use of your current interest in the moon. Go outside and look at it. Do you think you can determine if the moon is rotating on it axis, and if it is rotating, how fast it is doing so? Probably you would like to use some low-power binoculars for your observations. Hint, briefly sketch the main mountains and valleys on the moon. If the moon is rotating, your drawings should show changes from day to day. (Don't be distracted by the various phases, just sketch what you can see of the lit portions of the moon.) (Please note that there is a tricky wrinkle in this problem! Use your head as well as your eyes and sketch pad.)