What is the brightness (candlepower) of the sun?

we take the measured solar irradiance spectrum at Earth (solar irradiance vs. wavelength) and multiply by the luminous efficiency function (luminous efficiency vs. wavelength), then integrate under the resulting curve. The result is the illuminance due to the Sun at the Earth, and equals 133,000 lux. From that result, and knowing the distance between the Earth and the Sun, we can immediately find the luminous flux of the Sun, 3.75×10 28 3.75×1028 lumens. Dividing by 4? 4? gives the luminous intensity of the Sun, 3.0×10 27 3.0×10 27candelas. A candela is essentially the same as the old “candlepower” unit, which was the luminous intensity of a standard candle made of some specified materials, so we can estimate that the brightness of the Sun is equivalent to the light emitted by 3.0×10 27 3.0×1027, or 3 octillion candles.