I had to complete a similar project to this for my science class at school, and found an achievable way of doing it.
You will need to make sure that you have 9 Styrofoam balls overall, one for each of the planets and a particularly large one for the sun. The other balls will also need to be in a variety of sizes, make sure you have a couple of small ones and some larger ones.
I found that spray paint worked best to cover the balls, but any paint can be used. You will need:
- Yellow for the Sun
- Blue and green for Earth
- Red for Mars
- Brown for Mercury
- Brown/yellow for Venus
- Red/brown for Jupiter
- Yellow for Saturn
- Blue for Uranus and Neptune, although make them varying shades.
Use a picture of the solar system and match up as best you can the different sized balls to the different sized planets, then paint them correspondingly.
Once the balls have been painted and dried with their primary colour, detail can be added if you wish.
For Saturn you will need to make its rings, this can be done by cutting a large circle in card, and then cutting a smaller circle in middle of this, then gluing it in place around the ball.
You will then have all of your planets. To display them you can either stick them to a background such as a large piece of black card, or hang them from string in the form of a mobile. Just make sure you put the planets in the right order!