A planet having average surface temperature T₀ at an average distance d from the sun. Assuming that the planet receives radiant energy from the sun only and it loses radiant
energy only from the surface and neglecting all other atmospheric effects we conclude:

• A

  ${\mathrm{T}}_0\infty {\mathrm{d}}^2$

• B

  ${\mathrm{T}}_0\infty {\mathrm{d}}^{-2}$

• C

  ${\mathrm{T}}_0\infty {\mathrm{d}}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$

• D

  ${\mathrm{T}}_0\infty {\mathrm{d}}^{\raisebox{1ex}{$-1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$