20110116

Astronomy final exam question: Mars closer to sun?

Astronomy 210 Final Exam, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

[20 points.] Suppose Mars had instead formed closer to the sun, in Venus' orbit. Explain the expected characteristics of this closer-to-the-sun Mars, in terms of its internal heat and geological activity, compared to Mars today in its current orbit.

Solution and grading rubric:
  • p = 20/20:
    Correct. Extent of internal heat and geological activity of a terrestrial planet depends on its mass, thus Mars would essentially have the same amount of internal heat and geological activity at any distance from the sun.
  • r = 16/20:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
  • t = 12/20:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least recognizes that internal heat and geological activity is correlated with mass.
  • v = 8/20:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion based closer proximity to the sun creating more greenhouse effect and/or more geological activity.
  • x = 4/20:
    Implementation/application of ideas, but credit given for effort rather than merit. Decides on same/different relative amount of internal heat and geological activity without supporting statements.
  • y = 2/20:
    Irrelevant discussion/effectively blank.
  • z = 0/20:
    Blank.
Grading distribution:
Section 70158
p: 4 students
r: 3 students
t: 2 students
v: 29 students
x: 3 students
y: 0 students
z: 1 student

A sample "p" response (from student 1122):

A sample "v" response (from student 4321), discussing how more heat from the sun would cause more volcanic activity:

Another sample "v" response (from student 1986), again discussing how more heat from the sun would cause more volcanic activity:

No comments: