Cuesta College, San Luis Obispo, CA
Observers in San Luis Obispo, CA will see a total lunar eclipse in the evening of September 27, 2015.[*][**] There will not be a total lunar eclipse in the following month because:
(A) the moon always keeps the same side facing Earth.
(B) the moon's orbit around Earth is tilted.
(C) the moon's orbit is not a perfect circle.
(D) Earth's axis precesses over a 23,000 year cycle.
[*] timeanddate.com/eclipse/lunar/2015-september-28.
[**] eclipse.gsfc.nasa.gov/LEplot/LEplot2001/LE2015Sep28T.pdf.
Correct answer (highlight to unhide): (B)
When the moon is full and the moon's orbit is seen edge-on from the sun's perspective, there will be a total eclipse as the moon passes completely behind Earth, in Earth's umbral shadow. However, the moon's orbit will typically change its tilt such the subsequent full moon will no longer pass directly behind Earth, being either too high or low to pass into Earth's umbral shadow, making it just a regular full moon instead of a total lunar eclipse.
Response (A) explains why the near side of the moon appears to be constant; response (C) explains why some solar eclipses are annular rather than total; and response (D) is the reason why Polaris will not always be the pole star.
Section 70158
Exam code: quiz02s5Sz
(A) : 3 students
(B) : 25 students
(C) : 13 students
(D) : 1 student
Success level: 63% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.83
Section 70160
Exam code: quiz02Nnz2
(A) : 0 students
(B) : 16 students
(C) : 13 students
(D) : 0 students
Success level: 57% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.75
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