20150919

Astronomy quiz question: evening star Mercury?

Astronomy 210 Quiz 2, fall semester 2015
Cuesta College, San Luis Obispo, CA

The locations of Earth, Mercury and Venus are shown in the diagram below (not to scale, and orbits have been simplified as circles instead of ellipses).


At sunset (6 PM), Mercury will be:
(A) low over the east horizon.
(B) somewhere high up in the sky.
(C) low over the west horizon.
(D) not visible in the sky.

Correct answer (highlight to unhide): (C)

If a dashed line is drawn from Earth to the sun, the observer at sunset (6 PM) is located perpendicular to that line.


Everything below that line would be below the horizon, such that Mercury is visible at sunset, low in the west horizon, just over the setting sun. (However, Venus would not be visible at sunset, as it would be below the west horizon.)

Section 70160
Exam code: quiz02Nnz2
(A) : 7 students
(B) : 2 students
(C) : 12 students
(D) : 8 students

Success level: 45% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

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