Astronomy current events question: warmer/wetter Mars evidence

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, "Caltech Researchers Take the Temperature of Mars' Past," October 17, 2011
http://astronomy.com/en/News-Observing/News/2011/10/Caltech%20researchers%20take%20the%20temperature%20of%20Mars%20past.aspx

Researchers at the California Institute of Technology analyzed __________ from Mars to provide evidence that Mars was warmer and wetter in its past.
(A) look-back time photons.
(B) polar ice reflections.
(C) a Russian probe that returned.
(D) a meteorite that originated.
(E) surface gamma-ray emissions.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 2 students
(B) : 6 students
(C) : 2 students
(D) : 31 students
(E) : 5 students