Astronomy current events question: Dione's impact crater rays

Astronomy 210L, spring semester 2017
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!)

NASA/JPL-Caltech/Space Science Institute, "Rays of Creusa" (February 20, 2017)
jpl.nasa.gov/spaceimages/details.php?id=PIA20521

Rays of lighter ejected material from an impact crater on Saturn's moon, Dione observed by NASA's Cassini spacecraft can be used to determine the __________ of geological features on its surface.
(A) chemical composition.
(B) sequence of events.
(C) radioactivity.
(D) water content.
(E) roughness.

Correct answer: (B)

Student responses
Sections 30679, 30680
(A) : 10 students
(B) : 12 students
(C) : 1 student
(D) : 2 students
(E) : 6 students