Search Results (18)
Comets played an important role in the revolution of astronomy and cosmology that occurred between 1500 and 1700. In the earlier Aristotelian geocentric cosmological scheme, the universe was divided into two regions with very different characteristics. The heavens, which reached from the sphere of the Moon to that of the fixed stars, were perfect and unchanging; motion there was exclusively circular. Below the Moon was the world of corruption and change. The Earth was the center of the universe, the natural place of all heavy bodies (bodies in which the element earth predominated). Around it were arranged in successive spherical shells the elements of water, air, and fire. The sphere of fire reached up to the sphere of the Moon, the first heavenly sphere. Although there are references in Aristotle that some of the imperfection of the sublunary region may have rubbed off on the Moon, basically the divide between the heavenly and sublunary regions was absolute.