If both distance and size are proportional to that in the solar system, the model would be essentially useless. For example, if the sun were represented by a marble 1 cm in diameter, the planet Neptune would be represented by a grain of sand. 3 mm in diameter about 32.3 meters (106 ft) away. The largest planet, Jupiter, would be a larger sand grain, 1 mm in diameter, about 5.6 meters from the sun. Earth would be less than 0.1 mm in diameter, about 1 meter away from the sun. Such a model would barely fit into a gymnasium (basketball court), and the elements of it would be very difficult to find without a map.
