20090423

Astronomy quiz question: distant galaxies and lookback time

Astronomy 210 Quiz 6, Spring Semester 2009
Cuesta College, San Luis Obispo, CA

As seen from the Milky Way, a distant galaxy will:
(A) not appear to contain dark matter.
(B) not have absorption lines that are redshifted.
(C) have type Ia supernovae that explode slowly.
(D) appear as it did in its past.

Section 30674
(A) : 2 students
(B) : 3 students
(C) : 2 students
(D) : 25 students

Correct answer: (D)

Due to the finite speed of light, a galaxy that is n light years away will appear to us as it did n years in the past, when that light first left that galaxy.

"Difficulty level": 79% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.31

1 comment:

P-dog said...

Astronomy 210 Quiz 6, Spring Semester 2009
Cuesta College, San Luis Obispo, CA

Section 30676
(A) : 6 students
(B) : 3 students
(C) : 4 students
(D) : 39 students

Correct answer: (D)

"Difficulty level": 74% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.55