Firmament - Scientific Development

Scientific Development

The Greeks and Stoics adopted a model of celestial spheres after the discovery of the sphericity of the Earth in the 4th to 3rd centuries BCE. The Medieval Scholastics adopted a cosmology that fused the ideas of the Greek philosophers Aristotle and Ptolemy. This cosmology involved celestial orbs, nested concentrically inside one another, with the earth at the centre. The outermost orb contained the stars and the term firmament was then transferred to this orb. (There were seven inner orbs for the seven wanderers of the sky, and their ordering is preserved in the naming of the days of the week.)

Even Copernicus' heliocentric model included an outer sphere that held the stars (and by having the earth rotate daily on its axis it allowed the firmament to be completely stationary). Tycho Brahe's studies of the nova of 1572 and the comet of 1577 were the first major challenges to the idea that orbs existed as solid, incorruptible, material objects.

In 1584, Bruno proposed a cosmology without firmament: an infinite universe in which the stars are actually suns with their own planetary systems. After Galileo began using a telescope to examine the sky, it became harder to argue that the heavens were perfect, as Aristotelian philosophy required. By 1630, the concept of solid orbs was no longer dominant.