Relative Size of Planets: Scale Model of our Solar System

Mathematicians and all persons of reason are taught to question everything. And yet, from the time I was a child fascinated with the stars and planets in our solar system, I assumed that the pictures in all of the books were accurate. That couldn’t have been further from the truth. Not a single picture I every saw had a disclaimer that said, “not drawn to scale.”

This week, the children found out exactly how incorrect those pictures can be. They created an accurate to scale model of our solar system planets, including Pluto. They then looked a number of other pictures of our solar system to determine which was the most accurate representation. 

We started with a random piece of Kinetic Sand. It is likely your children will be asking you to purchase this magic sand. First, it is not magic (it is 98% real sand with 2% polymer). Second, you need not purchase it; although, it could be fun. They are tasked to create their own scale model of our solar system with whatever material they can find. Play-doh is probably the easiest. They can also use Clay,Model Magic, Mashed Potatoes, Hummus, Tofu, etc. Zero cost material would be soil or dirt from your yard. It will harden with a little water.

I taught them how to handle this material and cut it into 10 equal parts. They came up with strategies which included forming a uniform rectangular prism, score it in half, then cut off a perpendicular fifth; then cut the remainder in fourths giving you a total of 10 equal pieces. We practiced then cutting that tenth into tenths and more tenths until we reached a single grain of sand that was one 1,000,000th of the original piece.

The first step in the process is to take six tenths (or three fifths) is combine them together to make Jupiter. Then follow the remaining 10 steps on the attached pdf. 

 IN ORDER OF SIZE, YOU WILL HAVE CREATED THE NINE PLANETS TO SCALE. Then we looked at the ratios of the planets to Pluto as one (left column) and then Earth as one (middle column).

For example, since Mercury is a 9 to Pluto at 1 we say that:

·  the ratio of the sizes of Mercury to Pluto is 9 to 1 or 9:1 or 9/1

·  Mercury is nine times the size of Pluto (Mercury is 900% of Pluto)

·  Pluto is one ninth (1/9) the size of Mercury (Pluto is 11.1% of Mercury)

PLANET RELATIVE SIZE (by volume or mass)

PLANET PLUTO IS 1 EARTH IS 1   DIAMETER IN MILES

Jupiter 1,200,000 1,200 88,730

Saturn    718,000   718 74,940

Neptune                      40,000     40 30,775

Uranus        40,000     40 31,763

Earth                               1,000       1   7,926

Venus                                900 0.9    7,521

Mars      90 0.09    4,222

Mercury        9 0.009                  3,031

Pluto 1 0.001    1,430

The Sun           1,960,000      865,000

The Sun is 1,960,000 times bigger than Earth 

The Sun is 1,633 times bigger than Jupiter.

1) Create your own solar system using Play-doh, Clay,

Model Magic, Mashed Potatoes, Hummus, Tofu, etc.

2) Use the ratios from steps 1-11 above to make sure the

planets are accurate relative size.

3) Label your planets.x