Sorting Out Science

This week’s “sciencey” tourism picture is of an early attempt at a model of the solar system by Johannes Kepler, on display at the Technisches Museum, Vienna (Wien):

From the placard:

According to Ptolemaic belief, the distance between the planets were determined by “spheres,” which supported each other. On the other hand, to describe data from observations, the new Copernican world view had to act on the assumption of changed (relative) distances between the planets. However, at first it was not possible to theoretically justify this concept. Johannes Kepler (1571-1630) worked towards an explanation and introduced a model in his 1596 work “Mysterium Cosmographicum” (The Sacred Mystery of the Cosmos) whereby the alternating distances of the planets could be geometrically calculated by means of the so-called “platonic bodies.” The order was, from the outside to the inside: Saturn - Cube - Jupiter - Tetrahedron - Mars - Dodecahedron - Earth - Icosahedron - Venus - Octahedron - Mercury. Despite insignificant differences of the model from the observations, its inventor later abolished it.

Unfortunately the museum placard neglects to mention that the “insignificant differences” boiled down to the fact that the planets follow elliptical (vs. circular) orbits — one of Kepler’s big contributions to our knowledge of the solar system and our understanding of physics.

Click on the above picture to get to the Flickr version of this image — it’ll give you lots of options for resizing and otherwise manipulating the source photo.

Technorati Tags: Astronomy, History, solar system, Space, theory vs. reality