The Rise of Copernicanism
Aristotle had placed the Earth at the
centre of the universe, not because it was the most important place, but
because it was the coldest, most impure place in the cosmos and it would therefore
fall as far as it could - to the centre. The celestial bodies were made out of
a very pure and perfect element and travelled on the surface of spheres, the
most perfect geometric shape.
The mediaeval Church adopted this system,
and for Christians the Earth was central as being of the place of the cosmos’
salvation. Not surprisingly astronomical observation of the planets fitted only
erratically with this Earth-centred (geocentric) scheme and complicated
explanations were devised to overcome these anomalies. These were refinements
on Ptolemy’s system (2nd Century CE). In the 1530s the Polish mathematician
Nicolaus Copernicus began to challenge the Ptolemaic model and suggest a sun-centred (heliocentric) model; this was
only published as Copernicus was dying (in his great book De Revolutionibus of 1543).
There followed a period of what T.S.Kuhn
has called ‘paradigm shift,’ a crisis in the (newly developing) scientific
community, in which two radically different models were in competition.Nor was it clear that Copernicus was right - his circular orbits gave no better
fit than its best geocentric competitor - that of the Imperial mathematician
Tycho Brahe. (See Tycho’s
system.) This is because the planetary orbits are in fact ellipses, a model
first proposed by Johannes Kepler (1571-1630), who was one of the very few
thinkers other than Galileo to adopt Copernicanism before 1600.
A key element in the crisis between heliocentrism
and geocentrism was the career of Galileo Galilei.
Email
link | Feedback | Contributed by: Dr.
Christopher Southgate
Source: God, Humanity and the
Cosmos (T&T Clark, 1999)
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