1) define retrograde motion and explain if it is observed,nightly, weekly, monthly, or on a yearly basis and
2) explain how Ptolomy and Copernicus each explained retrogrademotion.
3) explain how the orbit of a planet with an eccentricityvalue close to 1 compares to a planet with an eccnentricity closeto the value of 0.
4) explain how distance influences the orbitalspeed of a planet in orbit and
5) explain the role of distance and mass and the influenceit has on the orbital period of a planet.
