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Unformatted text preview: Astronomy 210 Spring 2011 Homework Set #4 Due in class: Friday, Feb. 25 Total Points: 50 + 5 bonus 1. The Cooling Nighttime Moon . This problem is wordy but is not difficult if you take it step by step. Each point on the Moon’s surface is illuminated by the Sun for about two weeks, and then is dark for about two weeks. This leads to changes in the Moon’s temperature. As we will later derive in class, the sunlight Moon has an average daytime temperature of about T d = 330 K. (a) [5 points] Although Kelvin units are the most useful for us in this course (and this problem!), to get a more intuitive feel, find the daytime lunar temperature in Fahrenheit. Recall that T (K) = T ( ◦ C) + 273, and that T ( ◦ C) = 5 9 [ T ( ◦ F)- 32]. Comment on the implications of your answer for possible future moonbases. (b) [5 points] Find the peak wavelength of the blackbody radiation emitted from the sunlight Moon. In what part of the electromagnetic spectrum does the Moon thermally radiate? (c) [5 points] Find the blackbody flux F emitted from the daytime Moon. Express your answer in Watt / m 2 . (d) [5 points] Now consider the nighttime half of the Moon. This region initially has temperature T d , but then cools because it loses energy due to its thermal radiation. Consider a region of the, but then cools because it loses energy due to its thermal radiation....
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