Shrinking the solar system down to size

Science · Space Exploration · ages 9-11

Name ______________________ Date ____________

In a correct scale model, the distances between planets are much bigger than the planets themselves.
Circle one: True False
If the Sun were shrunk to the size of a beach ball, what would Earth be the size of?
- A pea
- A basketball
- A grain of sand
Why do we use a scale model to picture the solar system?
- Because planets are too small to be measured accurately
- Because the real distances and sizes are too vast to picture directly
- Because the Sun and planets keep moving, so only a model stays still
Look at the bar chart from the scale model. Which planet needs the most open space between it and the beach-ball Sun?
- Mercury
- Venus
- Mars
In the beach-ball scale model, Earth sits about 26 metres from the Sun. If you built the same model at double the scale, about how far would Earth be from the beach ball, in metres?
Answer: ______________
A classmate wants to build a model that fits in a shoebox, with the Sun the size of a marble and Earth just a fraction of a millimetre away. What's the problem?
- The size scale and the distance scale no longer match, so the model isn't accurate
- There is no problem, this is a good model
- The Sun would be too small to see
On the beach-ball scale, Earth sits about 26 metres from the Sun and Mars sits about 40 metres away. About how many metres separate Earth and Mars in this model?
Answer: ______________
Jay makes a model where the Sun is a beach ball and Earth is a pea placed just 30 centimetres away, right next to it. What mistake did Jay make?
- Jay made Earth the wrong size
- Jay got the sizes right but did not shrink the distance by the same amount
- Jay made the Sun too big

Answer key

For grown-ups. Fold this page away before handing over the rest.

Shrinking the solar system down to size W1-mt_TlGhXAqC4p-s1

True · That's the surprising part: the gaps of empty space are enormous compared to the sizes of the planets.
A pea · On that scale, Earth becomes tiny, about the size of a pea, next to the beach-ball Sun.
Because the real distances and sizes are too vast to picture directly · A scale model shrinks everything by the same amount, so we can see the true proportions on a small stage, like a playground.
Mars · Mars's bar is the tallest, meaning it needs the most space between it and the Sun.
52 · Doubling the scale doubles every distance in the model, so 26 metres becomes about 52 metres.
The size scale and the distance scale no longer match, so the model isn't accurate · If you shrink the distance to fit a shoebox without shrinking it the same amount as the size, the model no longer shows the real proportions. Real scale models need lots of open space.
14 · Subtract the two distances from the Sun: 40 minus 26 leaves 14 metres between Earth and Mars in the model.
Jay got the sizes right but did not shrink the distance by the same amount · The sizes might be right, but if the distance isn't shrunk by the same amount, the model doesn't show how empty and vast the space between planets really is.