## 20120920

### Astronomy quiz question: annular solar eclipse observed from the moon

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

Consider a side view of Earth and its shadow zones, and the moon and its shadow zones.  The sun is located to the left, far off of the page.  An observer on the side of the moon facing Earth would see:

(A) the sun, with no part of it being blocked.
(B) the sun, with part of its edge being blocked.
(C) the sun, entirely blocked.
(D) the edges of the sun, with the middle of it blocked.
(E) Earth, completely illuminated by the sun.
(F) Earth, illuminated with a small circular shadow on it.
(G) Earth, completely darkened.

The observer is on the side of the moon facing away from the sun, so this eliminates responses (A)-(D), which would only be observed on the side of Earth (or the moon) facing the sun.  The moon's antumbra (or "negative shadow") will only mask a small portion of Earth, with the remainder of Earth remaining illuminated in the moon's penumbra (in which only a portion of the sun's disk is blocked), or outside.   (Note that this diagram is not intended to be to scale.)

Section 70158
Exam code: quiz02k3P7
(A) : 0 students
(B) : 1 student
(C) : 1 student
(D) : 0 students
(E) : 3 students
(F) : 28 students
(G) : 2 students

Success level: 81% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.10

Section 70160
Exam code: quiz02n3Ap
(A) : 0 students
(B) : 2 students
(C) : 1 student
(D) : 1 student
(E) : 5 students
(F) : 18 students
(G) : 4 students

Success level: 61% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.27