Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.2
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] How do we know that the universe is expanding?
(A) The distance from the Sun to the Earth is increasing.
(B) The speed of light is slowing down.
(C) Distant galaxies appear to be moving away faster than nearby galaxies.
(D) Distant galaxies appear to be much younger than nearby galaxies.
Correct answer: (C)
Distant galaxies appear to be much younger than nearby galaxies, due to the finite speed of light, and not because the universe is expanding. Distances within the Milky Way remain constant, due to gravitational interactions. However, distant galaxies are receding faster than nearby galaxies, as described by Hubble's law, which demonstrates that space (between all galaxies) is expanding.
Student responses
Section 4136
(A) : 1 student
(B) : 4 students
(C) : 14 students
(D) : 10 students
Student responses
Section 5076
(A) : 2 students
(B) : 7 students
(C) : 10 students
(D) : 4 students
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Astronomy 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA
Student responses
Section 4160
(A) : 3 students
(B) : 2 students
(C) : 25 students
(D) : 3 students
Student responses
Section 5166
(A) : 5 students
(B) : 2 students
(C) : 28 students
(D) : 14 students
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