Two stars are the same size and the same distance away, but star B is three times as hot as star A. How much more power does star B radiate?

1. The energy leaving each square meter of a glowing body depends on temperature alone. 2. That flux is proportional to the fourth power of the absolute temperature. 3. Same size and same distance means the only difference left is temperature. 4. So raise the temperature ratio of 3 to the fourth power. 5. Three to the fourth power is 3 times 3 times 3 times 3, which is 81. 6. Star B therefore radiates 81 times the power of star A. 7. Answering 9 times squares the ratio instead of raising it to the fourth power. 8. Answering 27 times cubes it, one power short of the real law. _Source: OpenStax Astronomy (CC BY 4.0), Ch 4 "Earth, Moon, and Sky" and Ch 5 "Radiation and Spectra", section 5.2 The Electromagnetic Spectrum_