Modeling the Solar System (Grades 6-9)

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planets Student Data Sheet 1
Student Data Sheet 2
Student Data Sheet 3

The goal of this activity is to build a scale model of our solar system. Often we see pictures of planet whose sizes and orbits are in proportion, but they are not on the same scale. To overcome that issue, this activity includes two parts: 1) building scale models for the planets, and 2) spacing the planets the appropriate distances from the sun.

1. Use the diameter of the earth as the basis on which to build your model. First, determine the sizes of the other planets compared to Earth. Divide the radius of the other planets by the earth’s radius to calculate how much bigger or smaller than Earth these planets are. For example, Uranus’ radius divided by Earth’s radius is equal to 4.01. This means that in your model, the planet Uranus should be about four times the radius or diameter of Earth. Enter these numbers in your table.

2. Now find a size that works for building your model. Pick a round object, or make a ball of clay, that you think would be a good size for Earth. Measure its diameter. In your model, that length will be equal to 7928 miles. Given that size for the earth, how big will the biggest model planet have to be? How big will the smallest model planet have to be?

3. Once you have found a size for Earth that is reasonable, record your scale factor and fill in the lengths of the scaled diameters for the planets. Find or create objects that are fairly close to the size that the planets should be. Record those objects on the chart.

4. The diameter of the Sun is 863,886 miles. It is the largest object in our solar system. How many times bigger is the Sun’s diameter than the earth’s? Using your scale factor, if you built a model of the Sun, what would its diameter be? Do you have any object around you that would be close to the size of the Sun?

You now have a scale models of the planets. You still need to figure the distance from the Sun for each of the model planets. And you need to use the same scale so you get a better understanding of the size of our solar system.

5. In calculating the sizes of the planets, you used the diameter of the earth as the unit of measure. Use the diameter of the earth, 7,928 miles, as the unit of measure here too. For each of the planets, divide their distance from the Sun by the diameter of the earth to find out how far each planet is from the Sun in terms of the earth’s diameter. Record your data in the table for each planet.

6. Now use the numbers you just calculated, the Distance from Sun in terms of the diameter of the Earth, and multiply them by your scale factor to determine how far each planet should be from the Sun in your model.

7. Convert your data to other units to get a better grasp of the size of your scale model.

8. Will your model fit on football field? Within your city? Within your state?

9. Pick a place to be the Sun and find out where you would have to go to create your scale models of the planets Mercury, Venus, and Earth.