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Planetarium Activity

Turn off the daylight and horizon displays. Use the “Planet” Palette to center on Mars and lock on Mars. Click under the “C” column of the “Planet” Palette to track the celestial path of Mars among the stars. Set the date to April 1, 2005, and the time step to 2 days. Use the “Settings” button to select “Path Settings.” Turn the date off, and leave the Circular Marker and Connecting Line on. Click Apply and OK. Start the clock and watch Mars move among the stars. When Mars undergoes retrograde motion, wait until it is as far west among the stars as it gets during that retrograde loop and then stop the clock. Click on the constellation button on the “Display” Palette in the vertical toolbar to identify the constellation in which the retrograde motion occurred. Record the month of the retrograde and the constellation in which it occurs, and sketch the shape of the retrograde loop. Repeat for the next three retrograde loops. Use your data to estimate the synodic period of Mars. When do you think the retrograde motion of Mars will appear in the constellation of Taurus again? Do you see a pattern to the changes from one retrograde loop to the next?

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