Some recently discovered planets in other solar systems are so hot that they glow in the visible; they are literally “red hot” (e.g., do a Google search for “HD 149026b”).

(a) How many atmospheric layers would the Earth need before it glowed in the visible?

(Assume S = 1,360 W/m² and α = 0:3.) To answer this, you must first estimate what temperature the Earth has to be to begin glowing.

(b) Alternatively, what would the solar constant have to increase to for a one-layer planet with an albedo α = 0:3?

(c) How far would the Earth have to be from the Sun in order to have this solar constant?