## 20140222

### Astronomy quiz question: Venus and Mars as morning stars

Astronomy 210 Quiz 2, spring semester 2014
Cuesta College, San Luis Obispo, CA

A view of the horizon is shown below, as seen from San Luis Obispo, CA at a certain date/time. Carefully note the positions of Venus and Mars.

The locations of Venus and Mars are shown in the diagram below (not to scale, and orbits have been simplified as circles instead of ellipses). Which one of the choices (A)-(D) corresponds to the position of Earth? Clearly circle your answer below.

Correct answer (highlight to unhide): (D)

If Earth is at location (D), when a line is drawn from Earth to the sun, the observer at sunrise (6 AM) would see Venus low above the rising sun in the east horizon, and Mars high above the west horizon.

(Placing Earth at location (A) would have Venus and Mars both not visible at sunrise; placing Earth at location (B) would make Venus and Mars both visible low above the east horizon at sunrise; placing Earth at location (C) would only have Venus visible low above the east horizon at sunrise.)

Section 30674
Exam code: quiz02nF09
(A) : 5 students
(B) : 5 students
(C) : 2 students
(D) : 14 students

Success level: 56% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.43

Section 30676
Exam code: quiz02sCt8
(A) : 4 students
(B) : 6 students
(C) : 16 students
(D) : 18 students

Success level: 43% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.66