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Homework Help: Radiation question from a blackbody

  1. Apr 19, 2009 #1
    1. The problem statement, all variables and given/known data
    What should be the average temperature on Pluto, at its 5.9 * 10^12 distance from the Sun? Treat Pluto as a blackbody. Assume that the effective solar intensity is 68 %.

    2. Relevant equations
    Power of radiation = (sigma)eAT^4

    3. The attempt at a solution
    From the text, the power of the sun is 3.9 * 10^26 Watts. Since intensity if 68%, I multiplied that by .68 to get the new power. I then divided that value by e (given), the area (4(pi)r^2 where r is 5.9*10^12, and sigma (given, 5.7*10^-8). I then took the fourth root of that, and got 57 K. This is not the correct answer.

    For reference, the temperature with 100% solar intensity is 40.7 K. I could not replicate that either.

    Any help is appreciated, thanks!
  2. jcsd
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