Calculate the scale factor for each of the planets and the Sun by dividing the actual diameter by 10,000. Record your results in the table Pluto and Earth have been filled in for you. Your models of the planets and Sun will be one billion times smaller than the actual size. Notice that the actual diameters are measured in kilometers; your scale diameters are in centimeters.

Object	Actual Diameter in Kilometers	Scale Diameter in Centimeters
Sun	1,391,980
Mercury	4,880
Venus	12,100
Earth	12,800	1.28
Mars	6,800
Jupiter	142,000
Saturn	120,000
Uranus	51,800
Neptune	49,500
Pluto	2,300	0.23 cm (or 2.3 mm)

Use the modeling clay to create spheres with diameters that are close in size to the diameters you calculated for each planet. Begin with Pluto then create a model for each planet. Place the clay models of the planets on squares of cardboard and label each square with the name of the planet. As best you can, inflate your balloon to the approximate calculated size of the Sun. Position the models in correct order from the Sun, simulating the orbits of the planets. How do your scale models compare to your earlier predictions? What do you think is incorrect about your positioning of the planets around the Sun?

Additional Activities
Explore the following questions:

1. What other scale factors could you use to create models of the planets and the Sun?
2. Research the distances between the planets and the Sun. Create a scale factor that represents the distance of each planet to the Sun in yards. Place the models you created at the scaled distances you calculated. How far would you have to travel from your school to represent the distance between Pluto and the Sun?