Instructions for Doing This Lab: Print out this lab so you can work off line. If you want, attend the chat session on the lab after completing as much of the lab as possible. The date of the chat session is posted in the calendar in the Communications Center.

• Read the following secdtions in your text: Section 1.4, Section 22.4 on pages 529 and 530... up to Motion of the Moon (do not read past the Motion of the Moon section) and Section 23.1.
• Print out this Planetary Data Table and use it to answer some of the questions in this lab. Post questions to the discussion board and/or attend the lab chat session if you have any questions.

• Answer the following questions. To save time online, I suggest that you write your answers out on the printout of the lab.
  1. To what category of planet does the Earth belong?
  2. What is the distance of the Earth from the Sun? (Do not forget to include your unit.)
  3. Pluto is how many times farther from the Sun than the Earth? (Hint:  Remember that "time" and "difference" represent two different mathematical operations.)
  4. According to the data table, what is the radius of the Earth? (Be sure to round your answer to the nearest whole number and to include the unit of measurement in your answer.)
  5. In terms of their radii, how many times bigger is Jupiter than the Earth?
  6. In terms of their radii, how many times bigger is the Earth than Mercury?
  7. The density of the planets are measured in gm/cm^3.  What two physical properties of the planet are represented by this unit?
  8. What is the average density of the terrestrial planets?
  9. What is the average density of the jovian planets?
  10. What does the density of the terrestrial and jovian planets suggest about their composition?  (Keep in mind that water has a density of 1 gm/cubic centimeter.)
  11. Which group of planets is more massive, the terrestrials or the jovians.
  12. What is the average mass of the terrestrial planets?
  13. What is the average mass of the jovian planets?
  14. Explain how the Earth and the other terrestrial planets can have a relatively low mass, but a relatively high density?
  15. The term 'eccentricity' refers to the shape of a planets' orbit.  Eccentricity refers to the degree to which an orbit deviates from a circle.  Mathematically, the eccentricity of a circular orbit is equal to 0.  Orbits that deviate from a circle have eccentricities which are greater than zero and approach the value of 1.  Calculate the average eccentricity of the planets' orbits.
  16. Are the orbits of the planets closer to circles or are they highly eccentric? Explain
  17. All of the planets revolve around the Sun in an eastward direction. All but three of the planets rotate in the same direction as they revolve. The three which rotate in the opposite direction are said to have "retrograde rotation". Which three planets have a retrograde rotation? (Retrograde rotation is represented by a negative rotation period or clockwise rotation as viewd from the `north pole. )
  18. You will notice that the orbital velocity of the planets differ.  Calculate the average orbital velocity of the terrestrial planets.  (Round off to the nearest whole number and don't forget the unit of measurement.)
  19. Compare the orbital velocity of the planets with respect to their distance from the Sun.  Is the relationship between the distance of a planet from the Sun and its orbital velocity direct or inverse?  (A direct relationship exists if an increase in a variable produces and increase in a related variable.  On the other hand, an inverse relationship exists if an increase in a variable produces a decrease in a related variable.)  Explain how you drew your conclusion.
  20. The plane in which the orbit of a planet lies is referred to its "orbital plane".  Each of the nine planets has its own orbital plane.  The term "inclination" refers to the angle at which the orbital plane is tilted with respect to a plane that is the standard of reference.  Notice that the inclination of the Earth's orbital plane is 0.  Explain why?
  21. What is the average inclination of the the planets' orbits? (Be sure to exclude the Earth and Pluto from the average.)
  22. Why did I ask you to exclude the Earth from your calculation?
  23. Most of the planets are tilted on their axis.  What is the Earth's tilt?  (Round your answer to the nearest tenth and don't forget to include the unit of measurement.)
  24. The term "escape velocity" refers to the speed at which an object has to move in order to escape the gravitational pull of a planet. (Another way of thinking about it is if we were to launch a rocket to the moon, it would have to reach the escape velocity of the Earth in order to make it to the moon.)  What is the Earth's escape velocity in km/sec.  In mi/sec?  (1km = .6mi)
  25. Calculate the average escape velocity for the terrestrial planets in km/sec.  (Be sure to round to the nearest tenth and include in your answer the unit of measurement.)
  26. Calculate the average escape velocity for the jovian planets in km/sec.  (Be sure to round to the nearest tenth and include in your answer the unit of measurement.
  27. A planet's atmosphere consists of gases which are gravitationally bound to a planet.  The nature of the atmosphere depends on the escape velocity of a planet.  Would the terrestrial or the jovian planets be least likely to hold on to atmospheric gases?  Explain
      

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After answering the questions:

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• Resubmit THE ENTIRE LAB (both your your correct answers and the corrections you are making to your incorrect answers).