20111213

Astronomy multiple-choice question: solar system debris and IAU classification scheme

Astronomy 210 Quiz 7, fall semester 2011
Cuesta College, San Luis Obispo, CA

Refer below to 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 the following is classified as solar system debris?
(A) Pluto, a spherical body sharing Neptune's orbit.
(B) Ceres, a spherical body with an orbit between Mars and Jupiter.
(C) Cruithne, an irregularly shaped body sharing Earth's orbit.
(D) Phobos, an irregularly shaped body orbiting Mars.
(E) (More than one of the above choices.)
(F) (All of the above choices.)
(G) (None of the above choices.)

Correct answer: (C).

Solar system debris are objects that orbit the sun (meets qualification I), but are irregular in shape (does not meet qualification II), and also are unable to dominate/clear its orbit around the sun (does not meet qualification III). Thus according to the IAU classification scheme, Cruithne is the only solar system debris object in this list, as Pluto and Ceres are dwarf planets, and Phobos is a satellite.

Section 70158
Exam code: quiz07s3tI
(A) : 1 student
(B) : 2 students
(C) : 7 students
(D) : 4 students
(E) : 15 students
(F) : 1 student
(G) : 1 student

Success level: 30% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60

Section 70160
Exam code: quiz07n0N3
(A) : 1 student
(B) : 2 students
(C) : 9 students
(D) : 2 students
(E) : 9 students
(F) : 4 students
(G) : 1 student

Success level: 40% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.75

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