Astronomy current events question: Enceladus' water vapor cloud around Saturn

Astronomy 210L, fall semester 2011
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

Astronomy.com editors, "Saturn's Moon Enceladus Spreads Its Influence," September 22, 2011
http://astronomy.com/en/News-Observing/News/2011/09/Saturns%20moon%20Enceladus%20spreads%20its%20influence.aspx

The European Space Agency (ESA) Herschel Space Observatory used __________ to detect a huge doughnut-shaped water vapor cloud surrounding Saturn, created by its moon, Enceladus.
(A) infrared observations.
(B) Doppler shift measurements.
(C) time-lapse photography.
(D) long-range radar pulses.
(E) laser reflections.

Correct answer: (C)

Student responses
Sections 70178, 70186, 70200
(A) : 14 students
(B) : 2 students
(C) : 2 students
(D) : 3 students
(E) : 3 students