20140918

Astronomy quiz question: October 2014 total lunar eclipse and partial solar eclipse

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

Observers in San Luis Obispo, CA will see a total lunar eclipse followed by a partial solar eclipse, both occurring in October 2014.[*][**] The total lunar eclipse would occur a few __________ before the partial solar eclipse.
(A) minutes.
(B) hours.
(C) days.
(D) weeks.

[*] http://eclipse.gsfc.nasa.gov/OH/OHfigures/OH2014-Fig03.pdf.
[*] http://eclipse.gsfc.nasa.gov/SEplot/SEplot2001/SE2014Oct23P.GIF.

Correct answer (highlight to unhide): (D)

The total lunar eclipse occurs when the moon is in its full phase (such that the moon will be in Earth's umbra); while for the partial solar eclipse the moon is in its new phase (such that observers on Earth are located in the moon's penumbra.) Since these two eclipses will occur within the same month, these must be consecutive full and new phases, which is approximately two weeks between these phases.

Section 70158
Exam code: quiz02n3w7
(A) : 8 students
(B) : 11 students
(C) : 6 students
(D) : 17 students

Success level: 41% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.62

Section 70160
Exam code: quiz02k3pL
(A) : 4 students
(B) : 2 students
(C) : 7 students
(D) : 21 students

Success level: 64% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.44

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