Hi everyone. Firstly, I know that intensity= Power/Area. But this question made me my mind confused. The question shows the sun shining upon the Earth and the soln is: Only the hemisphere facing the Sun receives energy at any moment. power received by Earth = intensity × area of Earth facing the Sun And it shows the area of the Earth facing the sun is projected to a circle (pi R square, where R is the radius of the circle)!!!!!!! But shouldnt the area be the half the area of a Earth (sphere)???? Anyone can help me? Im really confused. Thanks.