Astronomy quiz question: galaxy recession

Astronomy 210 Quiz 6, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Observations that distant galaxies __________ is evidence that they are moving away from the Milky Way.
(A) are getting dimmer.
(B) are getting smaller in size.
(C) have redshifted absorption lines.
(D) appear much younger than the Milky Way.

Correct answer: (A)

Absorption lines that are shifted towards slightly longer values ("redshifted") indicate that its source is moving away.

Section 30676
Exam code: quiz06SoR3
(A) : 13 students
(B) : 6 students
(C) : 20 students
(D) : 0 students

"Success level": 56% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.64