We have a good spacial sense of short distances and lengths, and most peope can estimate short distances to a reasonable degree of accuracy. But as soon as distance and size become too large, we have to resort to what amounts to abstract thinking. Even a distance of a few kilometres is no longer easy to guess. It therefore follows that it is difficult, if not impossible for us to really grasp how vast the known universe is. However, by starting with the familiar and making step-by-step size comparisons, we can at least gain some idea of just how vast the universe is (and at the same time, how insignificant in fact we are!).

Whenever I give a public presentation on astronomy, I always start by attempting to convey an appreciation for the vastness of the universe. One of the ways in which I do this, is to give a demonstration in the form of a 'scale model' of the Solar System in which members of the audience participate. Once an idea of this  scale is established, I then give a few examples of larger distances on the same scale, e.g. the distance to Alpha Centauri, the size of the Milky Way Galaxy and so on.

In the download section of this web site you will find a set of printable A4 posters that may be used outdoors or in a hall to demonstrate the scale of the Solar System.

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