20110526

Astronomy quiz question: IAU classification scheme

Astronomy 210 Quiz 7, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Listed below are the minimal qualifications established by the International Astronomical Union for a planet:
I. Orbits the sun.
II. Shape "rounded-out" by gravity.
III. Cleared/dominates orbit around sun.
Of the following choices, which solar system object(s) only meets qualifications I and II?
(A) Mars.
(B) Io, a moon of Jupiter.
(C) Eris, a dwarf planet.
(D) Parnethope, an asteroid.
(E) (More than one of the above choices.)
(F) (None of the above choices.)

Correct answer: (C)

Eris directly orbits the sun (it is not a satellite of a planet), is round in shape, but does not dominate its orbit in the Kuiper belt around the sun.

Section 30674
Exam code: quiz07N3mi
(A) : 2 students
(B) : 2 students
(C) : 20 students
(D) : 1 student
(E) : 11 students
(F) : 0 students

"Success level": 60% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.43

Section 30676
Exam code: quiz07Sq5h
(A) : 1 student
(B) : 2 students
(C) : 21 students
(D) : 4 students
(E) : 12 students
(F) : 0 students

"Success level": 58% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.55

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