For thousands of years, people were confused about how the planets wandered among the stars. Mars, for example, would wander toward the West and then back up for a period of time only to move slowly toward the West again. In this activity students will actually plot the position of Mars on a start chart from a table of values. The plot will show how Mars backed up (called Retrograde Motion) for several weeks. A second construction on a diagram of the Sun, Earth, Mars and the star field will show that Retrograde Motion is an illusion - that Mars in its orbit around the Sun never really went backwards.