20110424

Astronomy quiz question: lookback time

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

The __________ makes it possible for a massive star that has already exploded as a type II supernova to still be observed as a supergiant in Earth's night sky.
(A) Hubble law.
(B) early inflation of the universe.
(C) expansion of space.
(D) finite speed of light.

Correct answer: (D)

The finite speed of light causes distant objects to appear as they did in the past, such that a massive star will still appear to be a supergiant, despite having already exploded as a type II supernova, if the light from the moment of this explosion were still traveling towards Earth.

Section 30674
Exam code: quiz06n4Ke
(A) : 6 students
(B) : 0 students
(C) : 2 students
(D) : 29 students

"Success level": 80% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.64

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