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Chapter 4: 1-4 Homework

Course Materials are always under revision! Weblecture content may change anytime prior to two weeks before scheduled chat session for content.

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Scholars Online Astronomy - Chapter 4: 1-4: Planetary Orbits


Reading Preparation

Reading: Astronomy, Chapter 4: Gravitation and the Motions of the Planets

Study Notes: notes on your assigned reading from the text

Key Formulae to Know

Synodic (phase to phase as seen from Earth S) and Sidereal periods (complete revolution on orbit P)

  • Inferior planets: add synodic and Earth inverses to get period inverse 1 P   = 1 E   +   1 S   
  • Superior planets: subtract synodic inverse from Earth's inverse to get period inverse 1 P   = 1 E     1 S   

Web Lecture

Read the following weblecture before chat: Aristotle, Ptolemy, Copernicus, Brahe: First steps to planetary theory, sections 1-4

Study Activity

Planetarium program: Set your planetarium location to your home location, and center it on a point between Libra and Scorpius. Set the time to 1 June 2018, and advance the planetarium one day at a time until 15 August. When does Mars stop moving eastward along the ecliptic? How long is it in retrograde? When does it stop moveing westward? How long is it "stationary"? When does it start moving eastward again?

Optional websites:

Play with the animations at the astronomy website at the University of Nebraska-Lincoln.

  • Select Venus on the Planetary Parameter drop down and start the animation. What pattern does the planet describe over time? Where is the sun as Venus moves around earth?
  • Select one of the outer planets (Mars, Jupiter, Saturn), and rerun the animation. What happens to the pattern? Where is the sun as this outer planet moves around earth?
  • Can this model account for change in brightness (planet moves nearer/farther from earth)?
  • Can this model account for stationary and retrograde motion?
  • Can this model account for variation in the rate of progress of the planet relative to the background sky as seen from earth?

Chat Preparation Activities

Chapter Quiz

Lab Work

Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.