Make a Scale Solar System

Decide if you want your model to show scale planet sizes or the scale distances between planets. You can combine a planet-size model of one scale with a distance model of another scale. But if you want size and distance to be the same scale, you’ll need to spread your model across at least half a mile! See Step 6 for instructions on building a combined size-and-distance model.

Pick a place to set up your solar system model. This could be across a bedroom wall, along the floor of a hallway or large room, outside in a yard, or down a sidewalk.

Keep your choice in mind as you calculate the size of planets and distances between them in the next steps. You'll need to have enough materials, and your model will have to fit within the place you choose.

Instructions for building a model out of beads and string, sidewalk chalk, or yard markers are included below, but you can use any materials or any space you like!

If you're making a scale-distance model, keep reading for two different methods of calculating scale distances. For a scale-size model, skip to Step 5.

1. Download the distance calculation chart (DOCX).
2. Multiply the scale factor on the chart by the distance to each planet in astronomical units (AU). Note: When using the suggested 10 centimeters per 1 AU, you’ll need about 10 feet between the Sun and Neptune. If you want your model to span a longer or shorter distance, you can change the scale value accordingly.

1. Download the Scale Distance spreadsheet (XLSX or CSV).
2. Create a formula in your spreadsheet that will calculate the distance from the Sun to each planet (in centimeters) in your model. The formula should multiply the AU value by the number of centimeters you want each AU to represent, your scale value.
3. A spreadsheet multiplication formula follows this format: =B3*10, where B3 is the cell with a planet’s AU distance and 10 is the scale value. B refers to the cell column and 3 refers to the cell row.

Try different scale values to make your scale model span a shorter or longer distance, depending on where you want to place it.

Once you've done your calculations, go to Steps 8-10 for a few different ideas for creating and displaying your model. You can also come up with your own creative display using your choice of materials.

If you're making a scale-size model, keep reading for two different methods of calculating the scale sizes of the planets. For a scale-distance model, see Step 4 above.

1. Download the size calculation chart (DOCX).
2. Choose the size (diameter) you want Earth to be in your model (for example 1 cm).
3. For each planet, multiply the size you chose for Earth by the multiplier value on the chart. The multiplier is a planet’s size compared with Earth. This will give you the scale size of each planet.

1. Download the Scale Size Calculator spreadsheet (XLSX or CSV).
2. Choose the size (diameter) you want Earth to be in your model (for example 10 cm).
3. Create a formula in your spreadsheet that will calculate the diameter of (distance across) each planet in centimeters. The formula should multiply the size you chose for Earth by the multiplier value for each planet. The multiplier is a planet’s size compared with Earth.
4. A spreadsheet multiplication formula follows this format: =B3*10, where B3 is the cell with a planet’s multiplier (its size compared to Earth) and 10 is the size you chose for Earth. B refers to the cell column and 3 refers to the cell row.

Try different values for Earth to make your scale planets larger or smaller depending on the materials you have available to represent the size of each planet.

Once you've done your calculations, go to Step 9 to find out how to make a sidewalk chalk scale model. You can also come up with your own creative display using your choice of materials.

About the image: This artist's rendering (available as a downloadable poster) shows the planets of our solar system lined up as if they were transiting the Sun. Although such a view would not be possible in reality, the graphic is intended to show the accurate scale of the planets, relative to each other and the Sun. › Full image and caption

If you are interested in a more accurate way to represent the solar system and have a lot of space (at least half a mile!) to work with, try making a model of the solar system that displays distance and planet size at the same scale. Otherwise, skip this step.

• Download the Scale Size and Distance Spreadsheet (XLSX or CSV) or the Solar System Sizes and Distances reference guide if calculating manually.
• Decide on the diameter of Earth in your scale model. Keep in mind that a 1-cm Earth means the scale distance from the Sun to Neptune is about two miles. Consider making your scale Earth just a few millimeters across. To calculate the scale solar system, you'll need to work with proportions and ratios, as shown in this equation.

• Using the actual diameter of and distance to a planet, along with your scale diameter of Earth, you can rearrange the equation to find the unknown sizes and distances. To start, use the scale diameter you chose for Earth, and rearrange the equation as shown below to solve for the unknown scale distance from Earth to the Sun. You can calculate this by hand or create a spreadsheet function that calculates this value.

• To calculate the scale diameter of the other planets, you need to rearrange proportional ratios and write equations similar to what you did in the previous step using the scale Earth diameter in your equation. By rearranging the equation below, you can calculate by hand or create a formula in the spreadsheet to find both scale diameter and scale distance for the remaining planets. Note: If you change the scale diameter of Earth in the spreadsheet, it will cause the functions to recalculate the scale values for the other planets as well.

• Next, use the scale Earth diameter and proportional ratios to find the scale distances to the other planets by rearranging the equation below.

• Repeat the previous steps for the remaining planets.
• Use a ruler, compass, string, protractor, or another tool to draw circles of appropriate sizes for each planet. You can color the circles to resemble the planets’ appearances.
• Using online mapping software, such as Google or Bing maps, right-click on the location that represents the Sun (e.g., your home) and click “measure distance” to identify where the scale planets should go. Depending on the calculated size of the scale model, you may want to check with neighbors and friends to see if they can host the more distant planets in your scale model.

Tie colored beads onto a string to make a scale model of the distances between planets in the solar system. You can wear your model or even display it on a wall.

• String (enough to span the distance to Neptune, plus an extra 30 cm)
• Beads, washers, or some other object to mark the distance to each planet on the string
• Calculated distances from Step 4

1. Measure and cut a piece of string about 30 cm longer than the distance you calculated from the Sun to Neptune.
2. Tie a bead representing the Sun to one end of the string using a double knot. If you don’t have beads, you can tie metal washers to the string, attach planet cutouts or trading cards, or simply use tape to mark the location of the Sun.
3. Using the distances (in centimeters) that you calculated, measure the distance from the Sun on the string to each planet and tie a colored bead in place using a double knot. If you can, choose beads that are the colors of the planets and the Sun.
4. Once you have attached all your beads or marked your planets on the string in some way, straighten out the string to see your scale solar system!

Use chalk to make a walkable scale model of the distances between planets and/or the sizes of planets in the solar system. Invite your family and friends to take a walk through your scale model.

• Sidewalk chalk
• Calculated distances from Step 4 or distances and sizes from Step 6

1. Use sidewalk chalk to draw the Sun on the ground.
2. Measure the distance you calculated to each planet and draw them at their scale distances.
3. If you calculated the planet sizes compared with each other, measure those sizes as you draw them, giving your planets the correct diameter.
4. You can draw your planets all along a single straight line from the Sun, but if you have enough space, consider drawing them at their correct distance in different spots in orbit around the Sun.

Use distance markers like cones or popsicle sticks in your yard or an open area to create a scale model of the distances between planets in the solar system.

• Popsicle sticks, cones, or other objects to mark distances
• Calculated distances from Step 4

1. Use distance markers like cones, ground stakes, or popsicle sticks to mark the locations of the planets at the distances you calculated.
2. Attach drawings or cutouts of the planets to their markers.