= Planetary equilibrium temperature
{title2=$T_{\rm eq}$}
For a planet of <Bond albedo> $A_B$ orbiting a <blackbody> star of radius $R_*$ and temperature $T_*$, complete global redistribution and negligible internal heat give
$$
T_{\rm eq}^4=(1-A_B)T_*^4\frac{R_*^2}{4a^2}.
$$
Uniform dayside-only reradiation replaces $4a^2$ by $2a^2$. The <planetary equilibrium temperature> describes absorbed stellar power; including an intrinsic cooling flux gives a total <effective temperature> $T_{\rm eff}^4=T_{\rm int}^4+T_{\rm eq}^4$, distinct from $T_{\rm eq}$. Neither quantity is necessarily the greenhouse-warmed surface temperature.
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