If the Earth were a football
Shrink the Earth to a football, a cricket ball or a marble, and shrink everything else by the same scale. See how big the Moon and the Sun would be, and how far away they would sit.
Core concept
A scale model divides every size and distance by the same number: if the Earth were a 22 cm football, the Moon would be a 6 cm ball 6.6 m away and the Sun a 24 m ball 2.6 km away, so space is mostly empty
Topic: Our planet and sky
The Earth is about 12 742 km across, the Moon 3474 km, and the Sun a huge 1 391 400 km. The Moon is about 384 400 km away and the Sun about 149 600 000 km. These numbers are too big to picture, so we make a scale model: we shrink everything by the same number, just as a map does. If the Earth were a football 22 cm across, we divide every size and distance by the same amount, about 58 million. Then the Moon is a small ball you could hold, but it sits several metres away, and the Sun is as tall as a building and kilometres away.
What you will learn
- Use one scale for every size and distance in a model.
- Compare the sizes of the Earth, Moon and Sun.
- Explain why space is mostly empty.
Before you start
- Convert between cm, m and km.
Materials
- A football, a small ball and a measuring tape
Equipment
- None
Procedure
- Record the model with the Earth as a football.
- Make the Earth a cricket ball, and record.
- Make the Earth a marble, and record.
How this simulation is simplified
- Diameters: Earth 12 742 km, Moon 3474 km, Sun 1 391 400 km.
- Average distances: Earth to Moon 384 400 km, Earth to Sun 149 600 000 km.