Q:  What does this method predict for the temperature of the Earth?


         T   =  277 Kelvin



  Q:  What is the actual temperature of the Earth?


         Pretty close to that value, actually.  The average temperature
         over the entire surface of the Earth, day and night together,
         is about 288 Kelvin.  It is slightly warmer than the prediction
         due to the greenhouse effect of the Earth's atmosphere, which
         adds complications that our simple method did not take into account.