Astronomy quiz question: IAU classification scheme for asteroids

Astronomy 210 Quiz 7, Fall Semester 2008
Cuesta College, San Luis Obispo, CA

[4.0 points.] 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.

Which of these qualifications are met by an asteroid?
(A) I only.
(B) II only.
(C) III only.
(D) Both I and II.
(E) Both II and III.
(F) Both I and III.
(G) (None of the above choices.)

Section 70160
(A) : 15 students
(B) : 1 student
(C) : 1 student
(D) : 2 students
(E) : 3 students
(F) : 2 students
(G) : 6 students

Correct answer: (A)

Asteroids orbit the sun, typically between Mars and Jupiter. However, they are irregularly shaped (if they were spherical, they would be dwarf planets), and they have not cleared out nor dominate their orbits (if they did, they would be planets).

"Difficulty level": 55% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.88