Building a solar system model is a hands-on way for your students to visualize the positions and size relationships of our neighborhood in space. But it is not practical to build a correctly scaled model. Guy Ottewell of the National Optical Astronomy Observatory points out that if you use an 8-inch ball to represent the sun, Earth would be the size of a peppercorn and the dwarf planet Pluto the size of a pinhead. The entire model would have a diameter of 1.58 miles.
Lay the cardboard box on the side so that the opening faces you. Paint the inside black or a very dark blue. Add a few stars and galaxies with white paint.
Sort the plastic foam balls into four sizes. The largest ball is the sun. The next largest are Jupiter and Saturn, followed by Uranus and Neptune, and then Mercury, Venus, Earth, Mars and Pluto.
Paint the plastic foam balls with tempera paints. The sun is yellow. Mercury is brown. Venus, Jupiter and Saturn are brownish-yellow. Mars is red. Earth, Neptune, and Uranus are blue. Pluto is black.
Cut five rings out of poster board. Four rings will make the planetary rings for Jupiter, Saturn, Uranus and Neptune. The fifth ring is the asteroid belt. It must be large enough to fit between the orbits of Mars and Jupiter
Glue the planetary rings to Jupiter, Saturn, Uranus and Neptune. Draw asteroids on the asteroid belt with felt markers while the glue dries.
Glue the sun and the planets to the tips of straws. While the glue dries, cut two pieces of fishing line that are the length of the box opening's width. Punch two holes with your scissors into the center of your display box's top.
Drop the pieces of fishing line through the holes so that all ends fall to the same height. Tie off the fishing lines with a knot at the display's ceiling so they won't slide around later.
Glue the straws supporting the sun and the planets to the display's bottom. Place the sun in the center, then: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Tie the ends of the fishing line to the asteroid belt's quarter points.
Leave enough space between Mars and Jupiter to hang the asteroid belt. Pluto is no longer considered a planet, so it's OK to exclude Pluto from your display. Use glow-in-the-dark paint for your stars and galaxies to make the display more interesting.
Use an apron or old clothes while working with tempera paints. They do not wash out completely.