Yet this move was inconceivable on the basis of an Aristotelian cosmology with its fundamental division between the sublunar and superlunary regions.

The sublunary spheres corresponding to the four elements are succeeded in the superlunary region by the concentric spheres of the sun and planets.

Arguably this conclusion was independently supported by the conclusion that the comet of 1577 was superlunary, because it showed less daily parallax than the Moon and thus must pass through any celestial spheres in its transit.

Gemma was one of the few astronomers - most famously Tycho Brahe, but also Helisaeus Roeslin, William IV, Landgrave of Hesse-Kassel and Michael Mästlin - who identified the comet as superlunary.