How big is Earth if the Sun is 1 metre wide?
About 9.2 mm — a pea-sized bead or small marble — and 107.5 m away from the Sun. Jupiter would be 10.0 cm across, 559.4 m away; Neptune 3.23 km away.
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How to make a solar system model to scale (school project)
If the Sun is a 1-metre ball, Earth is a 9.2 mm pea-sized bead or small marble 107.5 m away, and Neptune is 3.5 cm across and 3.23 km away. Real scale needs a playground, so most models use one scale for sizes and another for distances.
Steps
- Choose what is to scale. Sizes, distances, or both on separate scales. Write it on the label — teachers look for this.
- Pick the Sun’s size. Use the calculator below: type the diameter of the ball you have for the Sun.
- Find objects for each planet. The table suggests everyday objects of the right size (peppercorns, marbles, oranges, thermocol balls).
- Lay out distances. On a table, use a separate distance scale (for example 1 cm = 10 million km). Outdoors at real scale, pace out the distances in the table.
- Add facts. For each planet, note its distance, size, day and year (see the comparison table).
- Show where they are today. Bonus marks: arrange the planets at their actual positions for today — open the 3D simulator and look from above.
Size and distance calculator
| Object | Model diameter | About the size of | Distance from the Sun |
|---|---|---|---|
| The Sun | 1.0 m | a large exercise ball | — |
| Mercury | 3.5 mm | a small bead | 41.6 m |
| Venus | 8.7 mm | a chickpea | 77.8 m |
| Earth | 9.2 mm | a pea-sized bead or small marble | 107.5 m |
| Mars | 4.9 mm | a small bead | 163.8 m |
| Jupiter | 10.0 cm | an orange | 559.4 m |
| Saturn | 8.4 cm | an orange | 1.03 km |
| Uranus | 3.6 cm | a table-tennis ball | 2.06 km |
| Neptune | 3.5 cm | a table-tennis ball | 3.23 km |
Example: a 30 cm thermocol Sun
| Object | Model diameter | About the size of | Distance from the Sun |
|---|---|---|---|
| The Sun | 30.0 cm | a beach ball | — |
| Mercury | 1.1 mm | a mustard seed | 12.5 m |
| Venus | 2.6 mm | a peppercorn | 23.3 m |
| Earth | 2.7 mm | a peppercorn | 32.3 m |
| Mars | 1.5 mm | a mustard seed | 49.1 m |
| Jupiter | 3.0 cm | a table-tennis ball | 167.8 m |
| Saturn | 2.5 cm | a large marble or grape | 307.6 m |
| Uranus | 1.1 cm | a pea-sized bead or small marble | 618.9 m |
| Neptune | 1.1 cm | a pea-sized bead or small marble | 969.9 m |
Diameters from NASA JPL mean radii; distances are mean distances from the Sun.
Frequently asked questions
Can I make a solar system model to scale on a table?
Not for sizes and distances at the same time. If the planets are big enough to see, the distances run to hundreds of metres. Use one scale for sizes (on the table) and a second for distances (a chart, or pace it out on a playground), and say so on your label.
What size thermocol balls do I need for a solar system model?
If the Sun is a 30 cm thermocol ball, Jupiter is 3.0 cm, Saturn 2.5 cm, Earth 2.7 mm and Mercury only 1.1 mm. Many school models use a bigger Earth than this; if you do, state that the sizes are not to scale.
What should I write on my solar system project?
For each planet: its distance from the Sun, diameter, length of day and year, and one surprising fact. Every planet page on GalaxySim 3D lists these, with sources.