Astronomy quiz question: sidereal cycle

Astronomy 210 Quiz 1, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

An observer in San Luis Obispo, CA notices that the constellations Camelopardalis, Perseus, and Aries are just above the northeast horizon at 9:00 PM on August 31. Approximately how much time elapses until these three constellations will again be in the same position in the sky, just above the northeast horizon?
(A) 12 hours.
(B) 18 hours.
(C) 24 hours.
(D) 30 days.

Correct answer: (C)

It will take approximately 24 hours (23.93447 hours) for the stars to return to the same location in the sky. (Note that students were allowed to use their starwheels (planispheres) for this quiz.)

Section 70160
(A) : 9 students
(B) : 0 students
(C) : 28 students
(D) : 4 students

"Success level": 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.27