Take the tour ×  I don't understand the solutions to a problem
about blackbody radiation and was wondering if anybody could
help me out.  Here is the question:  The sun can be considered
as a blackbody radiation source at temperature T = 5778 K.
Radiation from the sun which is incident on the earth is
reflected by the atmosphere such that the intensity hitting the
earth's surface is reduced by a factor R. Some of the radiation
emitted from the earth's surface is reflected by the atmosphere
such that only a fraction A leaves the atmosphere. If A = R =
0:1, what temperature would the earth be?  Then in the solutions
they state: This is obtained by first trying to find the power
from the sun which passes through unit area at the earth's
radial distance. This is given by:  $\frac{4 \pi r_s^2}{4 \pi
d_e^2}\sigma T_s^4$  where $r_s$ is the radius of the sun, $d_e$
is the distance between the earth and sun and $T_s^4 = 5778K$ is
the temperature of the sun.  I know that $\sigma T_s^4$ is from
the Stefan-Boltzmann law