## HOW FAR IS THE NEAREST STAR?

Now that we’re getting the hang of this model, we can try one more very interesting scale challenge.

If the "Big Ball" is the Sun, and the Earth is a large orange 968 metres away, then how far away on our model would the nearest star be?

The nearest star to our Sun is a triple-star system called Alpha Centauri. It is 40,396,400,000,000 kilometres away. (That’s 4.03964 x 10 km in scientific notation). That’s just over 40 trillion kilometres.

It’s hard to get our head around a distance of that size. Let’s see what it looks like on our model and we’ll get a better idea perhaps.

We know from our earlier calculations that 1 km is represented by 0.00647 millimetres in the model. So it’s simply a case of some multiplication. Namely, the large kilometres distance to Alpha Centauri multiplied by the millimetres that each kilometre represents.

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We get the answer in millimetres, which if we then convert to kilometres gives us the distance that Alpha Centauri is from the Sun on our model.

On the model it is 261,365 kilometres away.

That’s a long way! In fact it is almost exactly two-thirds the distance from the Earth to the Moon.

So here’s what that means: If the "Big Ball" at Naas is the Sun, and the Earth is a large orange 968 metres away, then we have to travel two-thirds the distance to the Moon, before we would stop and place our marker for where Alpha Centauri is on our model!

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