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Energy from the sun that reaches the earth

  1. Dec 18, 2009 #1
    The sun consumes about 600 million tons of matter per second, How much energy is that? Of this energy how much reaches the surface of the earth


    I solved the first part, but how do I start the second?
  2. jcsd
  3. Dec 18, 2009 #2
    Have you been given a value of the distance from the Sun to the Earth, and the diameter of the Earth? They are useful things to know in this context.
  4. Dec 18, 2009 #3
    Yeah I have the distance of and the radius. I know the speed of light. Problem I have is how does energy decrease over a distance with a speed
  5. Dec 18, 2009 #4


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    It's an inverse square law because, assuming the sun radiates equally in all directions, then the same amount of power is being spread out over a sphere of successively larger and larger surface area as the distance from the sun increases. This means that the power received (per unit area) at any location decreases with distance in inverse proportion to the area of that sphere.

  6. Dec 18, 2009 #5


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    What fraction of the solid angle surrounding the sun is subtended by the earth?
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