The Bible and Astronomy
Avalos, Hector, Free Inquiry
Long before telescopes and sophisticated instruments, ancient peoples looked to the heavens for answers to the basic questions of life. From the very first verse, the Bible, the most influential collection of books in Western civilization, purports to provide answers to some of these questions, claiming that the Hebrew god created the heavens (Genesis 1:1) and that he made the Earth for human beings to inhabit (Isaiah 45:18). Heavenly luminaries were formed to provide light for Earth and markers for the seasons (Genesis 1:14-16). The Earth was the center of the biblical universe.
The relationship between the Bible and modern astronomy has been very complicated and often turbulent. For most of the last two thousand years, any research on astronomy had to follow the biblical interpretation of the Church, as the case of Galileo in the seventeenth century illustrated. Accordingly, many scientists would argue that, for modern astronomy to be born, biblical cosmology had to die.
GALILEO VS. PTOLEMY (AND THE CHURCH)
Galileo took one of the first steps leading toward the death of biblical cosmology by mounting a systematic challenge to the biblical notion that the Earth was the center of the universe. The centrality of Earth had long been associated with the cosmologies of Aristotle and Ptolemy that had been adopted as the official teaching of the Church. These cosmologists held that an immovable Earth was orbited by concentric spheres in which the various planets and stars were embedded. A complex series of circular motions by each sphere and the associated celestial bodies was purported to account for all observable heavenly motions, including the apparent retrograde motion of some planets. The heavenly bodies, such as the Moon and Sun, were perfectly homogeneous in their composition and structure.
In contrast, Galileo sought to confirm the theory, most forcefully presented in the sixteenth century by the Polish astronomer Copernicus in his De Revolutionibus Orbium Coelestium, that the Sun was the center of the universe. As Alexander Koyre, William Shea, and other historians of science have noted, most of Galileo's arguments were no better empirically than those of Ptolemy, and definitive confirmation of the Copernican system was found long after Galileo's death.
Galileo's certainty seems to have rested on the assumption that mathematical simplicity is a guide to truth. Even if two otherwise contrary systems could account for heavenly motions, the simpler mathematical model should be preferred. Galileo's faith in mathematical simplicity is evident in his famous Dialogo (after 1744 titled Dialogue Concerning the Two Chief World Systems, Ptolemaic and Copernican):
Who is going to believe that nature . . . has chosen to make an immense number of very huge bodies move with incalculable speed, to achieve what could have been done by a moderate movement of one single body around its own center?
But even if Galileo's mathematically simple model did not constitute proof that the universe actually worked in this manner, Galileo announced other discoveries that cast doubt on Aristotelian-Ptolemaic cosmology. Such discoveries were facilitated by Galileo's innovative use of the telescope to explore the heavens beginning around 1609. Galileo showed, for example, that the Moon's surface has mountains and valleys, and is not perfectly smooth as Aristotle postulated; that the Sun has spots, not a homogeneous surface; and that Venus has phases, which would not be expected if Venus moved uniformly around the Earth.
The Church reacted against such challenges by placing Copernicus' De Revolutionibus on the index of prohibited books in 1616, 73 years after its publication and indicating that the Church saw no early threat by this "revolutionary" work. In 1633 Galileo was tried and found guilty of teaching the Copernican system. His sentence included imprisonment, which was commuted to house arrest at his home near Florence for the remaining years of his life. …