The Size and Distance of the Planets

In this activity, you'll investigate the concepts of relative size and distance by creating a basic model of our solar system.

 This image shows Saturn's famous rings. Faint rings can be found around Uranus, Jupiter, and Neptune.
 What You'll Need 9 - pieces of paper 1 - roll of toilet paper 1 - ruler 1 - set of planet printouts (provided) or 1 compass to draw your own 1 - pair of scissors 1 - calculator 1 - long hallway or outdoor space of at least 110 feet (30.5 meters). You can make a partial model if your space is smaller. 1 - table with measures of planet radius and distance to the Sun relative to scale

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What to Do
Cut out the planet printouts provided, or using the measurements in the table above, use your compass to draw circles on paper. Note that this activity uses two scales: one for the printouts and cut-outs (larger), and one for the distances between the planets (smaller). This is due to the enormous distances involved. The planet cut-outs would be too small to use in our scale model.
If you choose to draw your own circles, label each planet. Cut the circles out and use them as your planets.
Choose a point at one end of a hallway, large room, or outdoor space as the Sun and mark it as your starting point.
Without looking at the table, place each planet in order of the distance you think they are from the Sun. As a reference, use 22.4 inches (57 centimeters) for the distance between Earth and the Sun.

Using the table, measure the distances by rolling out the toilet paper. Mercury is 1.9 sheets relative to the Sun, Venus 3.6 sheets from the Sun, etc. See how well your family did at estimating the distances. Move the planets to their proper distances, and you've built a scale model of the solar system.

What's Going On
This activity helps demonstrate the immense scale of our solar system. The sizes of the planets vary greatly as do the distances between planets and their distance from the Sun. The size of the Sun at larger scale (which isn't included in printouts) would have been 76.7 inches (195 centimeters) in diameter (38.4 inches in radius).

 Related Websites The Nine Planets www.dkrz.de/~k202045/tnp/ nineplanets.html Build a Solar System Simulator www.exploratorium.edu/ronh/ solar_system
Derived from "A Toilet Paper Solar System Scale Model": from Project Pulsar, St. Louis Science Center.

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