### Scaling the Solar System

Making a physical scale-model of the solar system can really drive home basic ideas about our little corner of space.  Below is the Lab Report I have my students prepare before we take a solar system walk.

I first share how we know the sizes of the suna and planets and how we know the distances to them.

Then introduce the ida of scale size, then ask them to write down a couple preconceptions about size and distance.

Then we use an 8″ bowling ball to represent the Sun, and we do the math establishing a scale of 1 inch for every 100,000 miles.

Given the real size of the planets teams of students determine the scale size and make a model using clay.  Then we establish the distances and go outside to lay the Sun and planets on the ground to the same scale as their sizes.

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.

Prediction: If an 8” bowling ball represents the size of the Sun, what common object would represent the size of the Earth, to scale? (5 pts)

a.

1. 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?? (5 pts)

b.

The Sun is about eight hundred thousand miles wide in diameter. The bowling ball is eight inches in diameter.

1. Calculate the scale factor. Work it out on a different piece of paper, then neatly copy your work here: (3 pts

1. Scale factor (distance) 1 inch = ________________ miles. (2 pts)

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.

1. Scale model of the Earth must be about ____________ inches in diameter. 3 pts)

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 (30 points)

Object

Diameter (miles)

Scaled diameter

(inches)

Distance from the Sun (miles) Scaled Distance

(inches)

Scaled Distance (yards)
Sun 860,000   NA NA NA
Mercury        3,000        36 million
Venus        7,500        67 million
Earth        8,000        93 million

### The Moon

2,200   249,000 *   NA
Mars        4,200      142 million
Jupiter      89,000      485 million
Saturn      75,000      889 million
Uranus        31,800   1.8 billion
Neptune      30,700   2.8 billion
Pluto          1,500   3.7 billion

* For the Moon, calculate the distance from Earth

Small groups will be assigned one of the Solar System objects in Table I. Your group will make a sphere of the approximate scale and attach your scale model to an index card.   (5 points)

Other Group members ________________________________________

Solar system object _________________     c. Approximate size (drawn)

Scaled diameter ____________________

6.  Compare your predictions (#1 above) to the observed data in Table 1.       How close to true were your predictions? (5 pts)

7.  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) (50 points)

Before writing the essay, we go outside, and put the bowling ball down.  I