From: henry@spsystems.net   
      
   In article <233c0280.0309231619.6e8bef59@posting.google.com>,   
   Beto  wrote:   
   >According to my calculations, the difference between the longest   
   >distance from earth to the sun and the shorstest one are about 4.8   
   >millions of kilometers.   
      
   That is at least roughly correct.   
      
   >Why the temperature doesn't drastically change because of this?   
      
   Partly because Earth has a lot of thermal inertia:  changes in the amount   
   of sunlight don't change its temperature quickly.   
      
   Partly because in the Northern Hemisphere, where most of the people live,   
   this trend is opposed to the seasons:  Earth is closest to the Sun in   
   January -- Northern Hemisphere winter -- so the changes due to distance   
   are hidden by the normal seasonal changes.   
      
   >If this is because of radiation doesn't being too important this far   
   >from the sun, Where can I find a equation which relates radiation with   
   >distance?   
      
   Light intensity varies (to a good approximation) inversely with the   
   square of distance.   
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