Scaling the Solar System
Purpose: To understand the sizes and distances of solar system objects by making a scale model of the solar system based on the Sun as an eight-inch bowling ball.
Make a couple of Predictions: If an 8” bowling ball represents the size of the Sun, what common object would represent the size of the Earth, to scale?
How far away would that object (a. above) have to be from the bowling ball to represent the correct distance from the Earth to the Sun, to scale?
The Sun is about eight hundred thousand miles wide in diameter. The bowling ball is eight inches in diameter.
- Calculate the scale factor. Work it out on a different piece of paper, then neatly copy your work here:
2. Scale factor (distance) 1 inch = ________________ miles
The Earth is about eight thousand miles wide. If one inch represents a hundred thousand miles, what size must our model Earth be to scale? Divide the size of the real Earth by the Scale Factor to get the scale size for the model.
3. Scale model of the Earth must be about ____________ inches in diameter.
Using the Scale Factor, fill out the Scaled Diameter for each object in Table I.
Using the same Scale Factor, fill out the Scaled Distances for each object in Table I.
Do not calculate a scaled distance for the Sun; we’re going to use it as our starting point.
Also, measure the scaled size and distance of the Moon from the Earth.
Table I : Scaling the Sizes and Distances of Solar System Objects
|Distance from the Sun (miles)||Scaled Distance
|Scaled Distance (yards)|
* For the Moon, let’s calculate the distance from Earth
Using modeling clay, make scale models of the planets. Attach each model of a planet
to a 3 X 5 index card.
Take a bowling ball, a yardstick, your planet model(s) and the table above and go outside. Place the model of the Sun, the 8″ bowling ball on the ground. Carefully measure the distance to Mercury at this scale (10 yards?) and place the model of Mercury on the ground. Measure the distance to each planet from the Sun and place the appropriate planet models at the appropriate distances from the bowling ball.
At the Earth, turn and look at the bowling ball. The bowling ball should have an apparent diameter of about a half of a degree. This is about the same as the apparent diameter of the Sun in our sky. If your model matches, then your scale is correct.
Finish placing the planet models on the ground the appropriate distance from the Sun model, stopping to look back at the Earth model and the Sun-model.
At this same scale, the next closest star, Proxima Centauri, would be about the size of a tennis ball. At this same scale, that tennis ball would be as far away as Juneau, Alaska is from High Point, North Carolina, 2,800 miles.
- Review your prediction (#1 above.) How close to true was your prediction?
- On another paper, describe in detail what you just learned about the scale of the solar system. (1st paragraph: your preconceptions, 2nd: sizes, 3rd: distances, 4th: current understandings)