Sections Review

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astronomical unit epicycle geocentric
heliocentric instrumentalism Occam's Razor
paradigm Pythagorean paradigm realism
retrograde motion

Review Questions

  1. What two basic kinds of models have been proposed to explain the motions of the planets?
  2. What is the Ptolemaic model? What new things did Ptolemy add to his model?
  3. Why are epicycles needed in Ptolemy's model?
  4. Why was the Ptolemaic model accepted for more than 1000 years?
  5. In what ways was the Ptolemaic model a good scientific model and in what ways was it not?
  6. What is the Copernican model and how did it explain retrograde motion?
  7. Why did Copernicus believe in his model?
  8. Why did Copernicus not know the absolute distance between various planets and the Sun in his model? Explain what he would have needed to know to get the absolute distances.
  9. What important contributions did Tycho Brahe make to astronomy?

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last updated: 06 May 2001

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Author of original content: Nick Strobel