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7

No they did not know this. The motion of the Sun, Moon and planets (as seen from the Earth) was known, in the sense that it could be predicted with reasonable accuracy. To do this, they used an ingenious model, approximating the periodic motions by combinations of circular motions, the same principle that is used nowadays for predictions of celestial ...


1

Tycho' observations impacted on numerous levels. First, it presented an accurate, detailed calculation of the motion of the heavenly bodies. At the time, 2 theories existed; helio- and earth-centric. The debate, via religion gravitated to the latter. Yet, facts are stubborn things. Given data, Kepler formulated his 3 Laws. The accurate observations where ...


4

In process of finding his laws Kepler tried to construct circular motions for planet orbits. The best fit disagree with observations by 8 minutes. Kepler knew that Brahe's observations could not have such errors, so he had to reject his hypothesis. Ptolemy's observation do not have such accuracy. For stars he give coordinates rounded to 20' or 15'. So yes, ...


3

Brahe's observations were crucial. More than the other things that you mentioned: Copernicus system and knowledge of periods. Copernicus system indeed simplifies calculations for planets a lot, but everyone understood how to transfer in principle calculations in one system into another. Periods+Copernicus system would be enough for the discovery of the Third ...


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