Astronomy current events question: Enceladus' global ocean

Astronomy 210L, fall semester 2015
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!)

Dwayne Brown, Laurie Cantillo, Preston Dyches, "Cassini Finds Global Ocean in Saturn's Moon Enceladus" (September 15, 2015)
nasa.gov/press-release/cassini-finds-global-ocean-in-saturns-moon-enceladus

Images taken by NASA's Cassini spacecraft of Saturn's moon, Enceladus indicate that a global ocean may lie underneath its icy crust, based on measurements of its __________ variations.
(A) temperature.
(B) tidal force.
(C) rotation rate.
(D) icy crust thickness.
(E) magnetic field.

Correct answer: (C)

Student responses
Sections 70178, 70186
(A) : 4 students
(B) : 6 students
(C) : 15 students
(D) : 6 students
(E) : 1 student