Astronomy current events question: Saturn's north-polar hexagon color changes

Astronomy 210L, fall semester 2016
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!)

Tony Greicius, "Changing Colors in Saturn's North" (October 21, 2016)
saturn.jpl.nasa.gov/resources/7539/

Changes in color of Saturn's north-polar hexagon observed by NASA's Cassini spacecraft may be caused by __________ in its upper atmosphere.
(A) helium flashes.
(B) gravitational instabilities.
(C) seasonal changes.
(D) methane rain.
(E) photosynthesis.

Correct answer: (C)

Student responses
Sections 70178, 70186
(A) : 2 students
(B) : 3 students
(C) : 15 students
(D) : 2 students
(E) : 2 students