20121230

Astronomy final exam: bigger than asteroids, smaller than planets

Astronomy 210 Final Exam, fall semester 2012
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was answered with a description of the Internal Astronomical Union's dwarf planet category:
The [International Astronomical Union] made a new category called dwarf planet for things too big to be asteroids but still too small to be planets.
Discuss how this statement is true using Ceres as an example, and how you know this. Explain using the International Astronomical Union classification scheme.

[*] Adapted from http://answers.yahoo.com/question/index?qid=20100503182538AAA3HVP.

Solution and grading rubric:
  • p:
    Correct. The online comment is correct, as Ceres needs to satisfy the first two of the three IAU requirements (orbits the sun, has a rounded shape, cleared/dominates its orbit) to be a dwarf planet, and would otherwise be classified as an asteroid if it only satisfied the first requirement.
  • r:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Discussion of IAU requirements, or why online comment is correct is not clear.
  • t:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problematic discussion of IAU requirements and why online comment is correct.
  • v:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU requirements.
  • x:
    Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU requirements.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Section 70158
Exam code: finalSor3
p: 22 students
r: 2 students
t: 4 students
v: 5 students
x: 0 students
y: 1 student
z: 0 students

Section 70160
Exam code: finalNon0
p: 25 students
r: 1 student
t: 1 student
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 1105):

Another sample "p" response (from student 1211):

A sample "y" response (from student 0304):

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