Illustration of a cosmological model by German astronomer Johannes Kepler (1571-1630) published in his 1596 book, 'Mysterium Cosmographicum' (The Cosmic Mystery). The model shows the relative distances of the planets from the Sun in the Copernican system. Copernicus' system, a revolutionary new heliocentric (sun-centred) theory, had been published in 1543, the year of his death. Initially it caused little controversy but Kepler became an advocate and published 'Mysterium Cosmographicum' to support the Copernican system. The work put forward the idea that the distances of the planets from the Sun were determined by the five regular solids seen here, if one supposed that a planet's orbit was circumscribed about one solid and inscribed in another.