HW2 - Astronomy C10 : HW 2 Introduction to Astronomy...

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Unformatted text preview: Astronomy C10 : HW 2 Introduction to Astronomy Homework 2 Problems from Pasachoff and Filippenko 1. (11 points) See the course reader. 2. (4 points) If someone were to say that we cannot know the composition of distant stars, since there is no way to perform experiments on them in terrestrial laboratories, how would you respond? 3. (4 points) A spectral line from the left side of Saturn’s rings, as you see them, is at a wavelength slightly shorter than the same spectral line measured fro the right side of Saturn’s rings. Which way (direction) is Saturn rotating, and why? 4. (4 points) The Earth’s average temperature is about 27◦ C. What is its average temperature in kelvins? (Requires a numerical answer) 5. (4 points) An iron rod is heated by a welder’s torch. Initially it glows a dull red, then a brighter orange, and finally very bright white. Discuss this sequence in terms of black-body radiation. 6. (4 points) Does the Doppler effect depend on the distance between the source of light and the observer? Explain. 7. (2 + 2 = 4 points) (a) If one photon has 10 times the frequency of another photon, which photon is the more energetic, and by what factor? (b) Answer the same question for the case where the first photon has twice the wavelength of the second photon. (Requires a numerical answer) 8. (4 points) Consider a black body whose temperature is 3 K. At what wavelength does its spectrum peak? (We will see the importance of this radiation in the discussion of cosmology in Chapter 19). (Requires a numerical answer) 9. (4 points) How many times hotter than the Sun’s surface is the surface of a star the same size, but that gives off twice the Sun’s energy per second (that is, is twice as luminous)? 10. (7 points total) See the course reader. 1 ...
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This note was uploaded on 09/18/2010 for the course ASTRON 05989 taught by Professor Filippenko during the Fall '10 term at University of California, Berkeley.

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