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The effective temperature of the Sun (5778 kelvins) is the temperature a black body of the same size must have to yield the same total emissive power. The effective temperature of a star is the temperature of a black body with the same luminosity per surface area (F Bol) as the star and is defined according to the Stefan–Boltzmann law F Bol ...
This temperature, calculated for the case of the planet acting as a black body by setting =, is known as the effective temperature. The actual temperature of the planet will likely be different, depending on its surface and atmospheric properties.
Using this model the effective temperature of stars is estimated, defined as the temperature of a black body that yields the same surface flux of energy as the star. If a star were a black body, the same effective temperature would result from any region of the spectrum.
The temperature of stars other than the Sun can be approximated using a similar means by treating the emitted energy as a black body radiation. [27] So: = where L is the luminosity, σ is the Stefan–Boltzmann constant, R is the stellar radius and T is the effective temperature.
The table on the right shows how the radiation of a black body at this temperature is partitioned, and also how sunlight is partitioned for comparison. Also for comparison a planet modeled as a black body is shown, radiating at a nominal 288 K (15 °C) as a representative value of the Earth's highly variable temperature.
Although the spectra of such lights are not accurately described by the black-body radiation curve, a color temperature (the correlated color temperature) is quoted for which black-body radiation would most closely match the subjective color of that source. For instance, the blue-white fluorescent light sometimes used in an office may have a ...
Consequently, such planets have surface temperatures higher than their effective radiation emission temperature. For example, Venus has an effective temperature of approximately 226 K (−47 °C; −53 °F), but a surface temperature of 740 K (467 °C; 872 °F).
The effective temperature, or black body temperature, of the Sun (5777 K) is the temperature a black body of the same size must have to yield the same total emissive power.