When Nicolas Copernicus first theorized that the Sun was the center of the Solar System, NOT THE EARTH, complicated models of the planets were discounted. Putting the Sun and the center allowed astronomers to calculate the distances of Mercury and Venus from the Sun. In this activity, students will duplicate what earlier astronomers like Copernicus and Kepler discovered. The first two pages of this activity are intended to be duplicated in quantity for the class. Since a drawing compass must be used, it is suggested that the drawing students will make should be done with a sheet of cardboard underneath so as to NOT mar the desk top. Be certain to stress that students use very sharp pencils and that the circle they generate should ONLY TOUCH the angle for the planet in one spot (not two). At that spot they should place a dot to represent the planet.
An additional part of this activity has the students checking the accuracy of their work by using a formula to calculate percentage of error. The last three pages of this activity are in a cream color and are intended as answer sheets for the teacher.