In order to convey the dimensions and relative scale of the Solar System all sizes and distances are reduced by a factor of 109, resulting in a solar diameter of 1.4m, a diameter of 5 mm for Mercury, and a mean Sun–Pluto distance of close to 6 km. Stainless steel models of the planets (and the Moon) are mounted at appropriate distances from a yellow steel sphere representing the Sun. Ten of these Solar System Promenades have been constructed in Switzerland.