The solar luminosity, L☉, is a unit of radiant flux conventionally used by astronomers to measure the luminosity of stars. One solar luminosity is equal to the current accepted luminosity of the Sun, which is 3.839×10 W, or 3.839×10 erg/s. The value is slightly higher, 3.939×10 W (equivalent to 4.382×10 kg/s or 1.9×10 M☉/d) if the solar neutrino radiation is included as well as electromagnetic radiation. The Sun is a weakly variable star and its luminosity therefore fluctuates.
