Astronomy quiz question: transit of Venus

Astronomy 210 Quiz 2, spring semester 2012
Cuesta College, San Luis Obispo, CA

In a rare event, the planet Venus will be observed in June 2012 as a tiny dark dot in the middle of the disk of the sun, for observers in San Luis Obispo, CA, who are located in:
(A) Venus' umbra.
(B) Venus' penumbra.
(C) Venus' negative shadow.
(D) Earth's umbra.
(E) Earth's penumbra.

Correct answer: (C)

During an annular solar eclipse, the angular size of the moon is (slightly) too small to completely cover the sun, as seen by an observer in the negative shadow zone (the antumbra) of the moon. This is similar to a transit of Venus, where its comparatively tiny angular size makes it appear to be a dot as it moves across the disk of the sun. Again as in an annular solar eclipse, the observer is in the negative shadow zone of Venus.

Section 30674
Exam code: quiz02n0Is
(A) : 14 students
(B) : 6 students
(C) : 7 students
(D) : 4 students
(E) : 3 students

Success level: 27% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.27