Construct a one-billionth scale model of the solar system in your neighborhood. Start with the sun in your home, which at one-billionth its size would be about 5 feet in diameter. To represent Mercury, place a pea about 200 feet away from the sun, which would be far outside of your home. To represent Venus, place a marble about 100 yards away from the sun. To represent Earth, place a grape about 165 yards away from the sun. The moon can be represented by a small pea about a foot from the model of Earth. Additional planets can be placed as follows: Mars (a hazelnut) at 250 yards away, Jupiter (a grapefruit) at 860 yards away, Saturn (an orange) at 0.9 miles away, Uranus (an apple) at 1.7 miles away and Neptune (an apple) at 2.8 miles away.
Kids can make a simple model of a solar system with Styrofoam balls and dowel rods. Use a large ball, at least 6 inches in diameter, to represent the sun. Cut the dowels into eight rods, ranging from 3 inches to 10 inches long, and paint them black. One end of the dowel rods will be stuck into the planet, and the other will be stuck into the sun. Paint the planets the following colors: Mercury (1-inch ball), red; Venus (1 1/2-inch ball ), gray; Earth (1 1/2-inch ball), blue and green; Mars (1/14-inch ball), red; Jupiter (4-inch ball), striped; Saturn (3-inch ball), striped with rings; Uranus (2 1/2-inch ball), light blue; and Neptune (2 1/2-inch ball), light blue. Stick each planet into the dowel rod and then into the sun. Construct a stand out of Styrofoam or hang the model from the ceiling.
Because the planets are different sizes, they have different gravities. To demonstrate how weight changes based on the gravity of different planets or moons, paint three storage jars black. Add 10 oz. of sand in the first jar to represent the weight on Earth. Add 1.6 oz. of sand to the second jar to represent the weight on the moon. Add 23.6 oz. of sand to the third jar to represent the weight on Jupiter. Set all three sealed jars on the ground and lift each of them up, noticing how different the weight is among them.
Use an empty shoe box of other large box to construct a diorama. Cut out cardboard or construction paper circles to represent each planet in ascending order of size: Mercury, Mars, Venus, Earth, Uranus, Saturn, Neptune and Jupiter. Label each planet and write several facts about it on the back. Then hang the planets from the top of the diorama in their planetary order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Decorate the outside of your diorama with markers, crayons and construction paper.