Author Question: To explain retrograde motion as well as changes in planetary brightness, Ptolemy's model used ... (Read 88 times)

storky111

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To explain retrograde motion as well as changes in planetary brightness, Ptolemy's model used ________.
 
  Fill in the blank(s) with correct word

Question 2

Based on its orbit, give two reasons to revoke Pluto's planetary status.
 
  What will be an ideal response?



jasonq

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Answer to Question 1

epicycles

Answer to Question 2

It does not orbit in the ecliptic, but off by 17 degrees. It also has a more eccentric orbit than even Mercury or Mars, and can cut inside of the orbit of Neptune between 1979 and 1999 at perihelion.



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