What Size Styrofoam Balls for Solar System Model

Most children are enthralled by space. It captures their attention and introduces them to the universe and our place in it. Space is an excellent way to pique children’s interest in science and demonstrate how exciting the subject can be just like Gundam modeling for anime enthusiasts.  

Making a solar system model is both educational and visually appealing same with Star Trek model kits. Styrofoam balls make excellent planets because they are light, easy to hang, round, and available in a variety of sizes. Painting on Styrofoam is difficult due to the texture, and some paints, including spray paint, contain solvents that will simply melt the foam and turn it into a gooey mess. However, with the proper water-based paint and ball sizes, your model will receive numerous compliments.

Select Your Balls

Styrofoam balls

You’ll need 10 balls of various sizes to make a model of the solar system. You won’t be able to accurately represent the sun’s proportion to the planets because it’s far too large in reality. Instead, the sun should be represented by the largest of the balls. You’ll also need a Styrofoam ring to wrap around Saturn.

What You’ll Need

  • 6-inch sun ball 
  • 4-inch Jupiter ball 
  • 3-inch Saturn ball 
  • 2 1/2-inch Uranus ball
  • 2-inch Neptune ball
  • 1 1/2-inch Earth and Venus balls
  • 1 1/4-inch Mars ball 
  • 1-inch Mercury ball 
  • 3/4-inch Pluto ball

How do you make a model of the solar system out of Styrofoam balls?

Solar system -


  • Select the styrofoam ball that will represent each planet and sun.
  • Use parchment paper to line a baking pan or tray.
  • Select a planet.
  • Squeeze the acrylic paints onto a piece of paper.
  • Roll the styrofoam ball around on the paper by tilting the baking pan or tray.
  • Repeat until the entire ball is covered.

Why are planets made out of Styrofoam balls?

Making a solar system model is both educational and visually appealing. Styrofoam balls make excellent planets because they are lightweight, easy to hang, round, and available in a variety of sizes.

What type of paint should I use on Styrofoam planets?

If you have an air brush, you can use water-based air-brush colors instead. Insert a toothpick into the Styrofoam ball to use as a handle while painting the sun and single-color planets such as Mercury, Venus, Mars, and Pluto, and paint the entire ball in the suggested color.

Paint your planets using the following guidelines:

1. MERCURY – has a high iron content and very little atmosphere. Through a telescope, it appears dark gray and pockmarked. The now-retired NASA MESSENGER mission revealed that it is covered in a thick layer of dust and igneous silicate rocks.

2. VENUS – The true colors of this planet aren’t as interesting or informative as the common false-color composites. These combine various wavelengths of light to help us visualize things like surface features, atmospheric content, and activity. When viewed through an optical telescope, Venus appears to be a pearly white world with a slight yellowish tinge.

3. MARS – appears reddish-brown due to its dust, which contains a high iron content. And, like an old bike left outside, the dust has rusted. However, the planet is not as red as it appears in popular media.

4. JUPITER – like the Sun, Jupiter is mostly made of hydrogen and helium. It did not gather enough mass during formation to initiate fusion and become a star. It shouldn’t come as a surprise that a planet with such a dense atmosphere and a climate system that is remarkably similar to Earth’s would have tremendous storms like the “Great Red Spot.”


5. SATURN – Saturn’s overall appearance is hazy yellow-brown. The surface seen through telescopes and in spacecraft images is actually a complex of cloud layers decorated with many small-scale features that change over time, such as red, brown, and white spots, bands, eddies, and vortices.

6. URANUS- its blue-green color is caused by methane gas in the atmosphere. Sunlight enters the atmosphere and is reflected back out by the cloud tops of Uranus.

7. NEPTUNE – has an atmosphere composed of hydrogen, helium, and methane. Neptune has the same blue color as Uranus due to methane.

8. PLUTO – The visual apparent magnitude of this planet averages 15.1, brightening to 13.65 at perihelion. In other words, the planet’s colors range from pale off-white and light blue sections to yellow and subtle orange streaks to large patches of deep red.

How do you make a model of a rotating solar system?


1st step

Collect nine different-sized styrofoam balls. One large one for the sun, and smaller ones for each of the other planets. It’s okay if you can only find one size! It does not have to be exact.

2nd step

Paint the balls to look like different planets.

3rd step

Make a circle out of a large piece of thick cardboard. The larger the better, but at least one foot across is recommended. A frozen pizza’s base is ideal. These are the eight planets’ orbits. The first four planets orbit fairly close to the sun, leaving a space for the asteroid belt. The remaining four planets orbit a little further out, so make your circles reflect this.

4th step

Poke eight more holes in the cardboard with a nail or the tip of a sharp scissors, one along each orbit line. Distribute the holes evenly around the circle. You don’t want the planets to be too close together because you’ll be hanging them from these holes

5th step

Make nine equal pieces of string, each about a foot long. Tape one end of each string to a planet and thread the other end through the nine cardboard holes. To keep it in place, tie a knot.

6th step

Take three one-foot-long pieces of string and tape them at equal intervals around the top of your cardboard circle. Tie the tops of these to a long piece of string that will be used to hang your model.