Space is huge. But exactly how huge are the spaces between the Sun, Moon and planets? Find out by making a scale model of the inner solar system at your nearby park!
Credit: NASA
You will need
- Ruler
- Tape measure
- Basketball
- 2 Matchsticks or small pins
- Sewing pins with small and large heads
- Plastic cups or witches’ hats
- Pen
- Calculator (optional)
- Phone with measuring app (optional)
- Hat and sunscreen
Safety
Remember to be sun-smart with a hat and sunscreen. Tell an adult where you’re going before you go to the park.
What to do
1.
Source your celestial bodies from objects you have around the house. The table below tells you how big each model needs to be. Use a ruler to double check your model sizes.
| Space object | Actual diameter (km) | Model diameter | What we used |
| Sun | 1,392,700 | 242 mm | Basketball |
| Mercury | 4,879 | 0.8 mm | Pin with small head |
| Venus | 12,104 | 2.1 mm | Matchstick |
| Earth | 12,742 | 2.2 mm | Matchstick |
| Moon | 3,476 | 0.6 mm | Pin with small head |
| Mars | 6,790 | 1.2 mm | Pin with large head |
2.
Ask an adult to take you to a nearby park. Remember to be sun safe! And don’t forget to pack your model space objects, cups and tape measure.
3.
Pick a quiet area of the park to place your model Sun. We recommend picking a spot close to the park boundary, so you have plenty of space to spread out. The table below tells you the distances between space objects in real life and in your model.
| Space objects | Actual distance (km) | Model distance |
| Sun to Mercury | 58000000 | 10.1 m |
| Mercury to Venus | 51000000 | 8.9 m |
| Venus to Earth | 40000000 | 7.0 m |
| Earth to Moon | 384,400 | 0.07m or 70 mm |
| Earth to Mars | 79000000 | 13.7 m |
4.
Stretch your tape measure out so that you can see 1 meter. Practice pacing out exactly 1 meter with your feet. This might be two steps, one big step or one big hop. Choose a method that you’ll be able to repeat many times. You can also use an app to measure distances.
5.
With one foot next to your Sun, pace out 10 meters towards the inside of the park. Place your Mercury object here and mark it with a cup or a witches hat.
6.
With one foot next to Mercury, pace out 9 more meters away from your Sun. Place your Venus object here and mark it with a cup or a witches hat.
7.
With one foot next to Venus, pace out 7 more meters. Place your Earth object here and mark it with a cup or a witches hat. How big does the basketball appear from here?
8.
Use a ruler or tape measure to measure 7 centimetres away from your Earth, and put your Moon object here. Is this closer or further away than you expected?
9.
With one foot next to Earth, pace out 13.5 more meters. Place your Mars object and yet another cup or witches hat.
10.
Congratulations! You’ve completed a scale model of the inner solar system.
What’s happening?
A scale model can help us wrap our heads around the astronomical gaps between the planets. Were you surprised by the size of the planets in comparison to the distances you paced out? Typical models of our solar system have to blow up the planets so you can see them.
Did you know that the average person travels about 80,000 kilometres in their lifetime? That’s the same as going around the Earth twice! Which is just twice around the tiny matchstick in your model! That goes to show just how far away things are in space.
Adding Jupiter
What would it take to complete your solar system model? The outer planets are much further away so it’s unlikely the whole model will fit in your park. But don’t take our word for it, we’ll show you how to calculate it!
First, we needed to find a number to help us convert actual distances to your model’s distances.
We wanted the Sun to be a basketball, so we compared the diameters of those two objects. The Sun’s diameter is 1,392,700,000 metres while a basketball’s diameter is 0.24 metres. Dividing the Sun by the basketball gives us a big number: 5,754,900,000. It means that 5.75 billion metres in space is equal to just 1 metre in your model.
Next, we can use this number to convert real distances to model distances.
For example, Jupiter is 778,000,000 kilometres away from the Sun. Divide that by our number, 5.75 billion and we get 0.135 kilometers. That’s 135 metres away from your basketball.
You can follow the same steps to find the diameter of your model Jupiter. Real life Jupiter is 139,822,000 metres wide. We recommend finding a marble for your model.
Going further
At the edge of our solar system lies the Oort cloud, which might stretch 15 trillion (that’s a 15 followed by 12 zeros) kilometres away from the Sun. In your model that would be 2,600 kilometres away – that’s a 40+ hour car trip from your park!
How about the nearest star (other than the Sun)? Proxima Centauri is 4.2 light years away, which is equal to about 40 trillion kilometres away. In your model, that would be 6,900 kilometres – that’s a flight from Australia to Japan!
Leave a Reply