The grand, astronomical scale, clockwork movement and diverse nature of the solar system makes it a constant source of interest for scientists and any school students learning about astronomy. Making a simple model of the solar system can teach kids the locations of the eight planets (and five dwarf planets), and even a crude estimation of the scale can provide an insight into how mind-boggling massive our planetary neighbourhood is. The huge sizes and distances involved would mean that if you made the Sun 1.4 m (4 ft 7 inches) in diameter, then the dwarf planet Pluto would have to be a tiny 2 mm (5/64 of an inch) in diameter and almost 60 metres (or 197 ft) away to be accurate (see Resources 1)!
Go into a large clear space you can use for your model. Lay several pieces of paper or card out on the floor to provide a backing for your model. You’ll need around a metre square (3 ft 3 inches) for a comfortably spaced model, but you can make it bigger if you like. Choose a central location for your Sun, the 20 cm (8 inch) ball. The sheer size of this in comparison to the other objects is completely justified, because Jupiter (the largest planet) is ten times smaller than the Sun.
Poke the pin into the two pincushions, taking care not to touch the points of the pins. The head of the pins represent the planets; the pincushions just keep them in place. Place the first pin and pincushion combination close to the ball representing the Sun. It should be close to the ball, but the distance becomes much more illustrative than accurate when you go into the outer solar system anyway, so it doesn’t really matter precisely how far away it is. The pinhead represents Mercury.
Place a peppercorn around one and a half times further out from the Sun than Mercury. Remember, the planets orbit the Sun in a rough circle, so you can place your objects at any location around the central ball, just use your measuring tape to ensure each successive planet is further away. This peppercorn represents the planet Venus.
Position another peppercorn in orbit around twice the distance from the Sun-substitute ball as the Mercury pin-head. This peppercorn is the Earth. Place another pincushion and pin further out than the Earth peppercorn, around the same distance as from the model Sun to Mercury. This pinhead represents Mars.
Place the chestnut or pecan even further out, leaving a significant distance between it and the Mars pinhead. This represents Jupiter, which is actually around four times further from the Sun than Mars. Between these two planets, place a single piece of couscous. This represents Ceres, which is one of the five dwarf planets. This sits inside the asteroid belt, but for clarity you shouldn’t add substitutes for the asteroids in this model because Ceres would be quickly lost in the array of matter. If you want to: try grinding some pepper up in a circle between Mars and Jupiter – let it fall naturally from the grinder so each piece is reasonably well-spaced.
Put a hazelnut or acorn further out than Jupiter. Anything beyond the asteroid belt can be thought of as part of the outer solar system, and any form of distance scale will undoubtedly break down at this point (unless you have a huge space). The hazelnut represents Saturn, which is actually almost twice as far from the Sun as Jupiter. Just make sure the gap is notably larger than between the inner planets.
Continue with this outer solar system convention when you place the coffee beans or peanuts in place, which represent Uranus and Neptune, the final two planets. Get the scale as close as your space will allow. Really, Uranus is around twice the distance from the Sun as Saturn, and Neptune is about as far away from Uranus as Uranus is from Saturn.
Finish with four pieces of couscous for the dwarf planets. With this scale, the actual sizes of the dwarf planets would be much too small to be shown accurately, so the same size will have to suffice. Pluto is around twice as far from the Sun as Uranus, so compress this to suit your space as well as possible. Put another piece of couscous a little further out than Pluto, to represent Haumea, and another very close to it to represent Makemake. Finally, right on the edge of your model, add a last piece of couscous to represent Eris.