# Make your own solar system

## Project

*The following downloadable sheets may be useful:*

**Can you make a model of the solar system, so that both the sizes of the planets and their distances from each other and the Sun are all to scale?**

This is not a straightforward problem, since although the planets are very big, their diameters are much, much smaller than the distances between them and the Sun.

### Getting started

Collect the following resources:

- a toilet roll (unused and complete!) for each group of students
- a large blow-up ball (the bigger the better, to represent the Sun)
- a range of spherical (or nearly spherical) objects, ranging in size from a mustard seed up to small to medium-sized balls
- a large space - big enough to take an unrolled toilet roll, preferably indoors, since even a very slight breeze will move the toilet roll and small objects on it

The unrolled toilet roll will represent the distance from the sun - to be placed at one end - to the outermost planet.

Hint: Pluto is now classified as a dwarf planet rather than a planet. If you include it, you increase the distance you need to work with from 4,500 million km to 5,900 million km. It is probably best not to include it!

### Scaling the distances in the solar system

Use this table to help you decide how you are going to make your model. You could:

- make each piece of toilet paper a particular distance, say, 20 million km
- divide the total distance between the Sun and Neptune by the number of pieces in your toilet roll
- divide the total distance between the Sun and Neptune by the length of the toilet roll

Or you may have your own ideas about how you want to scale your model.

Mark where each planet will go on the toilet roll.

### Scaling the planets

Using the data in the table, start by putting the planets in order of size. Then pick objects to represent each planet.

Put the objects in the right places on the toilet roll.

- Which is the biggest planet?
- Which is the smallest?
- Which planets are closest together?
- Which are furthest apart?

**Improving your model**

If you wanted to use the same scale as you used for your toilet roll solar system to make models of the planets, how big would the biggest planet be? How big would the smallest be? Is this a practical scale for a model solar system?

If you made the smallest planet so that it had a diameter of 1cm, how big would the distance from the sun to Neptune need to be? How about if you represented the smallest planet with a mustard seed?

If you can, decide on a scale which will allow you to represent both the distances and the diameters of the planets. Find a long enough roll of paper (perhaps two or more toilet rolls stuck together), then either find suitable objects for each of the planets, or make them from modelling clay, papier mache, or similar.

If there isn't room to do this, you will need to agree that your planets and distances have to have a different scale. So how will you scale the size of your planets?

If you make your own planets, find out what colour they appear to be, and paint them.

### Working with your model

Make a colourful poster for each planet: more information about the planets.

You could include things like:

- how far it is from the Sun
- its diameter
- its mass
- any unusual features
- the number of moons, and their names if there aren't very many
- whether it is a rocky planet or a gas giant
- if it has an atmosphere, what is it made of
- how long its 'year' and its 'day' are
- its lowest and highest surface temperatures, and whether one side is always shielded from the Sun or not
- some calculations:
- how strong is its gravity, how high could you jump
- how fast would a rocket have to go to escape from its gravitational pull
- how long would it take an email to get from Earth to the planet
- how long it would take a rocket to get from Earth to the planet

- the problems humans have have to overcome if they were ever to establish a colony on the planet

Or you may have other things you want to find out about the planets which you could include.

*With thanks to the 'Don't Try This At Home' Club Fowlmere Primary School, Cambridgeshire for letting us visit them and take photos.*

## Teachers' Resources

Make your own solar system provides ideas for a STEM club for up to half a term.

This project links science and maths in an integrated way, and can be approached at a level appropriate to the students so that there is sufficient challenge for the more able, while providing an accessible project for others.

### What does this project offer your club?

This obvious focus of this project is astronomy but it also covers maths and science, and has the potential to be related to geography also. This should help students to integrate what they learn in lessons as they investigate the topic.

This project starts with creating a model of the solar system using an unrolled toilet roll for the distance between the Sun and Neptune. The initial task is to decide how this can be used to scale the distances involved. Once we add in the sizes of the planets, things get more complicated! How do we resolve the problem of representing different orders of magnitude in the same model?

When the model is complete, students can make posters describing the planets, and their potential for space exploration.

The model and posters or other artefacts would make an excellent display for a parents' night or other public event.

### Possible approach

This whole project is intended to be group activity. Depending on how many people there are in your club, you could divide students into smaller groups, or all work together. One possibility is to start off as a whole group, then let students work in smaller groups on particular questions they want to investigate further.

There are information sheets to help students get started:

- getting started - scaling the distances in the solar system
- scaling the planets and improving your model

While students are enjoying creating their model, they will have to make decisions about scale. A way into this is to start with relative distances and sizes - getting things in the right order - then introduce numbers.

You could start by unrolling the toilet roll in a large space and putting the largest ball available at one end for the Sun, and a fairly large ball at the other end for Neptune. Then ask the students to choose objects for the other planets, and to put them where they think they might go. This requires them to find out about relative sizes and their order out from the Sun. They should take some notice of the actual distances, rather than just putting them at regular intervals.

Then comes a key question: is this good enough, and if not, how do we make it more accurate?

This could lead into a brain-storming session, where students suggest how they might use the toilet roll to scale the distances. Once objects are placed on the toilet roll in the right places, it would be good to discuss how accurate the guesses were - are there any big surprises?

The next stage is to replace balls and small spherical objects with models or objects which are scaled correctly. Is it possible to use the same scale as the distance scale on the toilet roll? If not, why not?

How is this to be resolved? Are you going to use a different scale for distances and for planetary diameters? Or are you going to buy more toilet rolls to make a longer model? Or ... ?

### Key questions

- What information do we need to get started?
- Is our initial model good enough? How can we improve it?
- Do we start with the toilet roll, or with the distances from the Sun to the planets? Are we going to make our scale unit one sheet of toilet paper or some other number of sheets of toilet paper, or are we going to make our scale unit 10,000 km or some other number of km?
- If our scale unit is a number of sheets of toilet paper, how many km does the unit number of sheets of paper represent?
- If our scale unit is a number of km, how many sheets of toilet paper are we going to say are equivalent to the unit number of km?
- Once we have determined the scale, and put the planets in the right places on the toilet roll, what can we say about the solar system? What are our observations?
- Thinking about the sizes of the planets - what do we mean by 'size'?
- Given the unit we decided on for the distance model, can we represent the planets using the same unit?
- If not, how are we going to resolve the problem so we can finish our model?

### Other links

Basic data provides distances of the planets from the Sun and their diameters.

DIY data table is the worksheet students could use to help them work out distances and sizes on their model.

More data gives the numbers of moons and the lengths of days and years for each planet.