1. The problem statement, all variables and given/known data Assume that the radiation emitted from the Sun moves radially outward from the Sun and that no radiation is absorbed between the Sun and Earth. How much energy in the form of radiation will fall per second on an area of 1 m2 on Earth, if that area is perpendicular to the straight-line path of the radiation? The distance from the Sun to Earth is 1.5e11 m. Assume the total power output of the sun is 4.47 x 1026 W. 2. Relevant equations Stefan Boltzmann forumla - E(T) = [tex]\sigma[/tex]T4 3. The attempt at a solution Where I'm struggling is with the role the distance between the two bodies plays. Since the radiation is emitted radially outward, the distance between the two is relatively large, and the area on earth is relatively small, does this mean I need to observe an infinitesimally small "window" on the surface of the sun whose radiated waves will strike this area on earth? Or, since the 1m2 on the curved surface of the earth is relatively small I can assume that it, and a corresponding surface on the sun, is flat? The power output of the sun can be determined by a surface temp of 6000K and a radius of 6.95x108 m (we solved this in an earlier problem).