Cuesta College, San Luis Obispo, CA
[20 points.] Sir Martin Rees, Astronomer Royal of Great Britain remarked that, "we in astronomy have an advantage in studying the universe, in that we can actually see the past." Explain what makes this possible.
Solution and grading rubric:
- p = 20/20:
Correct. Explains how the finite speed of light causes distant objects to appear as they did in the past. - r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Describes how lookback time affects the appearance of distant objects, but does not explain how this is caused by the finite speed of light, and/or explains that this is caused by the expansion of the universe. - t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Discusses how the motions of objects that be backtracked to determine their motion at some time in the past. - v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. General discussion of how evidence is used to infer information about the past. - x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. - y = 2/20:
Irrelevant discussion/effectively blank. - z = 0/20:
Blank.
Section 30676
p: 39 students
r: 9 students
t: 2 students
v: 7 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 5659):
Another sample "p" response (from student 1192, who admits to somehow blanking out on this exam):
Another sample "p" response (from student 6969), leading off with some expository statements, but finishing on task:
Another sample "p" response (from student 6615), graphically illustrating the effects of the finite speed of light:
A sample "r" response (from student 0047):
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