The intensity of solar energy from the sun arriving at the earth's surface is aproximatly 1400 joules, per square meter, per second. The sun is 1.5 x 10^11m away from earth. At what rate is the sun radiating energy? per meter squared on its surface. The soloution is 1400 = E/(1.5* 10^11)^2 and that becomes 1400 / (1.5*10^11)^2 = E THe inverse square law is I = 1/d^2. However this equation replaces 1 with the E. Could someone explain why this is done?