Build your own Solar System

Recently I had a look at the scale of a load of the bigger objects in the solar system compared to the sun. But seeing the scale flat on a computer screen isn’t quite the same as seeing things in real live 3D! So here’s my attempt to build a little model with stuff I found around the house…

If you’ve had a look at the other blog piece, you’ll see it’s a bit of a challenge to get in the two ends of the scale, with the massive sun at one end and the tiddlers like the moon or mercury at the other. Because of that I left out some of the smaller objects this time, and just concentrated on the proper planets (sorry Pluto).

Here’s the ingredients to build your own solar system, starting from the middle (on the right hand side):

Gym ball photo courtesy of http://www.localfitness.com.au

The one important part of the Solar System you don’t see in that picture is the Sun (so it’s just a regular old ‘system’ at the moment…). Based on the scale I’ve used here, the Sun would be a 65cm gym ball. If you aren’t sure what that is, there’s a photo to the right. Pretty amazing that compared to that size of Sun, the Earth would be a small pea!

While the objects I’ve shown are about to scale with the planets they represent, the spaces between them certainly aren’t! To give you an idea of how spaced out the planets are, I also worked out how far apart these items would need to be placed to represent the average distances from the Sun. You can then do this in real life – but be warned – you’ll need a lot of room! Let’s give it a go.

Scaling things up

If you have a big space, and a trundle wheel, you could just measure out the distance between these objects using the info in the table below. However, assuming you don’t, here’s another way to think about it. You’ll need some professional size football pitches end to end. At least 20 actually. Or just a bit of imagination! It could also be a rugby pitch, an American Football pitch, or just a field – as long as it’s about 105m long you’re good to go.

Inner Solar System – Sun to Mars

Start by placing the Sun (gym ball) on the goal line, and begin walking towards the other end of the pitch. About 10 paces outside of the penalty area, you can put down tiny Mercury (sesame seed). Make sure you don’t lose it! Keep on walking, and a couple of paces short of the halfway line, put down Venus (your first small pea). Once you’ve crossed the halfway line, it’s another 18 paces or so before you’re ready to put down Earth – your second pea. Keep on going, and just as you step over the goal line at the far end of the pitch form the Sun, place Mars in the goalmouth – your lonely peppercorn.

So the inner solar system (which is what scientists call everything up to Mars) more or less fits on one football pitch. Here’s where things get a little more spread out!

Asteroid belt

On the second football pitch, you’ll hit the start of the asteroid belt a little before the halfway line – keep going onto the next pitch. You won’t have to do much ducking and diving though. The asteroid belt is actually pretty dispersed and not at an interplanetary assault course like science fiction movies would have you believe. You emerge from the asteroid belt as you get towards the penalty area at the far end of the third football pitch.

Outer Solar System – Jupiter to Neptune

By the time you put down Jupiter (tennis ball), you are in the centre circle on the far side of the halfway line on pitch number four, and the gym ball Sun is a good 360 metres away. It seems a long way, but you’ll have to travel almost as far again before placing the next planet!

Assuming you haven’t eaten it yet to keep you going, place Saturn (satsuma) down just short of the centre circle of pitch number seven.

By the time we get to Uranus, we’ve crossed 12 full pitches since leaving the sun, and are well over a kilometre away from our gym ball – a mere speck in the distance. On the 13th pitch, walk most of the length, then put Uranus (big marble or 10p coin) down just outside the far penalty area.

As we stagger onto the 21st consecutive football pitch, we can stick Neptune down (another big marble or 10p coin), just in from of the nearest goals, and look back to the gym ball over two kilometres away, no longer visible from the outer reaches of our ‘mini’ solar system (although the real Sun would be visible because it’s so bright!).

The edge of the Solar system

That’s where our scaled down planets end, but it’s far from the end of the Solar system. Somewhere out on the 27th football pitch you would pass Pluto (which was left out of this kit, as it isn’t a proper planet!). It’s now over 2700 metres back to our gym ball Sun, about the same length as San Francisco’s Golden Gate Bridge. Eventually, somewhere around the start of the 81st consecutive football pitch we reach an are called the heliopause, where the influence of the Solar wind (the blast of particles coming off the Sun) peters out. We’re now almost 8 and a half kilometres away from our exercise ball Sun now, or 18 billion kilometres in the real thing.

Consider yourself lucky to make it this far! You are only the second human-made object to make it out this far, after the Voyager 1 probe – which is still high-tailing it into interstellar space at about 17 kilometres a second.

Build by numbers!

Solar System	Object	Size	Distance from Sun (to scale)
The Sun	exercise/gym ball	65cm / 25″	0
Mercury	sesame seed	0.23cm	27m
Venus	small pea	0.57cm	51m
Earth	small pea	0.6cm	70m
Mars	peppercorn	0.32cm	106m
Jupiter	tennis ball	6.68cm	364m
Saturn	satsuma	5.63cm	669m
Uranus	UK 10p coin / US 25c coin (or large marble)	2.39cm	1344m
Neptune	UK 10p coin / US 25c coin (or large marble)	2.3cm	2103m