equilibrium temperature

A planet's equilibrium temperature (T_eq or planetary equilibrium temperature) is the temperature a planet would have given its incoming electromagnetic radiation (i.e., from its host star) if it were a simple black body, thus not subject to atmospheric windows, internal heat sources, etc. One simple determination calculates it from the host star's luminosity (calculable from its radius and temperature) along with the distance between star and planet. Sometimes the term is used taking albedo into account as well, and perhaps sometimes including other factors. Some cited equilibrium temperatures (sources vary):

In the case of extra-solar planets, sometimes the calculated equilibrium temperature is the only available temperature determination, but transit spectroscopy and spectrography over the course of the planet's orbit may offer an independent temperature determination for comparison.