# Build a Solar System

Build a Solar System

Make a scale model of the Solar System and learn the REAL definition of "space."

## To Do and Notice

• Fill in the diameter of the Sun you want your model to be scaled by. You can fill in either the red bordered inches box or the green bordered millimeters box.
Important: Only fill in one box. If both are filled in you will get a dialog box asking you to clear one of the boxes. Use the Clear button to clear the entire form.

• Click on the "Calculate" button.

• Notice that the distances and sizes of the planets will automatically fill in. I've also provided some other interesting scale comparisons at the bottom of the chart.

• You can now build your scale model. You can do this with a long tape measure, or you can measure the size of your pace and walk it off counting the number of steps you take. To mark a planet's place you can use a piece of paper on a post that you stick into the ground, or you can use a flag, or even a person. Be prepared for a long walk!

• If you build your solar system on a roll of toilet paper, you can make the Sun about .4 inches (10 mm) across and still fit the entire solar system on the roll. A standard roll of toilet paper has about 450 sheets that are about 4.375 inches long, hence the roll is about 164 feet long. You should check your toilet paper for length. Some are longer.

• You can click on the names of the planets and satellites to go the the Nine Planets web site page about them. LOTS of info there!

## What is Going On?

One of the most exciting exercises I ever did as a kid was to make a scale model of the Solar System. Most of the pictures in my books made the distance between planets seem small and easy to travel. Museums were no help either. The models they displayed usually had the sizes of the planets to scale, but the distances between them were a completely different scale, giving the impression of a rather close-knit family.

I made my first scale model on a roll of teletype paper tape (anyone remember that stuff?) On this 1-inch tape, my Sun was the size of the tape - 1 inch in diameter. It all started out well. Mercury was only about 3-1/2 feet from the sun and Earth was almost 9 feet from the Sun. What I didn't bargain for was that Pluto was 354 feet down the tape! I used up almost the entire roll.

I also calculated the sizes that I should make the dots that represented the planets. I found that even the largest planet, Jupiter, should have a spot size smaller than 1/8 inch. The other planets, especially the small rocky inner planets, would be virtually invisible dust spots.

Needless to say, this was an eye-opening experience. This one exercise taught me the real meaning of the word "space." It sure made me feel insignificant looking at the scale of the Solar System - never mind the rest of the universe!

Now we have great tools like spreadsheets to do the numerical computations for us. Below you can download OpenOffice (or Libre Office), Apple Numbers or Excel format files. In these spreadsheets, you set the scale of the model by entering a radius for the Sun. The sheets should then calculate everything else based on this number.